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Author Ke, X.
Title From top-down to bottom-up : from carbon nanotubes to nanodevices Type Doctoral thesis
Year 2010 Publication Abbreviated Journal
Volume Issue Pages
Keywords Doctoral thesis; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Antwerpen Editor
Language Wos Publication Date 0000-00-00
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor Times cited (up) Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:87408 Serial 1289
Permanent link to this record
 
 
Author Zhou, X.-G.; Yang, C.-Q.; Sang, X.; Li, W.; Wang, L.; Yin, Z.-W.; Han, J.-R.; Li, Y.; Ke, X.; Hu, Z.-Y.; Cheng, Y.-B.; Van Tendeloo, G.
Title Probing the electron beam-induced structural evolution of halide perovskite thin films by scanning transmission electron microscopy Type A1 Journal article
Year 2021 Publication Journal Of Physical Chemistry C Abbreviated Journal J Phys Chem C
Volume 125 Issue 19 Pages 10786-10794
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract A deep understanding of the fine structure at the atomic scale of halide perovskite materials has been limited by their sensitivity to the electron beam that is widely used for structural characterization. The sensitivity of a gamma-CsPbIBr2 perovskite thin film under electron beam irradiation is revealed by scanning transmission electron microscopy (STEM) through a universal large-range electron dose measurement, which is based on discrete single-electron events in the STEM mode. Our research indicates that the gamma-CsPbIBr2 thin film undergoes structural changes with increasing electron overall dose (e(-).A(-2)) rather than dose rate (e(-).A(-2).s(-1)), which suggests that overall dose is the key operative parameter. The electron beam-induced structural evolution of gamma-CsPbIBr2 is monitored by fine control of the electron beam dose, together with the analysis of high-resolution (S)TEM, diffraction, and energy-dispersive X-ray spectroscopy. Our results show that the gamma-CsPbIBr2 phase first forms an intermediate phase [e.g., CsPb(1-x)(IBr)((3-y))] with a superstructure of ordered vacancies in the pristine unit cell, while a fraction of Pb2+ is reduced to Pb-0. As the electron dose increases, Pb nanoparticles precipitate, while the remaining framework forms the Cs2IBr phase, accompanied by some amorphization. This work provides guidelines to minimize electron beam irradiation artifacts for atomic-resolution imaging on CsPbIBr2 thin films.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000655640900061 Publication Date 2021-05-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447; 1932-7455 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.536 Times cited (up) Open Access Not_Open_Access
Notes Approved Most recent IF: 4.536
Call Number UA @ admin @ c:irua:179187 Serial 6880
Permanent link to this record
 
 
Author Corthals, S.; van Noyen, J.; Liang, D.; Ke, X.; Van Tendeloo, G.; Jacobs, P.; Sels, B.
Title A cyclic catalyst pretreatment in CO2 for high yield production of Carbon nanofibers with narrow diameter distribution Type A1 Journal article
Year 2011 Publication Catalysis letters Abbreviated Journal Catal Lett
Volume 141 Issue 11 Pages 1621-1624
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract This paper presents a cyclic catalyst pretreatment process to improve the CNF yield with narrow size distribution by sequentially feeding the CVD reactor with CH4/CO2 mixtures (carbon deposition) and CO2 (carbon removal) prior to the actual growth process. A mechanism based on a break-up of large Ni particles tentatively explains the beneficial effect of the cyclic carbon deposition/removal CVD procedure.
Address
Corporate Author Thesis
Publisher Place of Publication Basel Editor
Language Wos 000296471400006 Publication Date 2011-09-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1011-372X;1572-879X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.799 Times cited (up) 1 Open Access
Notes Iwt; Iap Approved Most recent IF: 2.799; 2011 IF: 2.242
Call Number UA @ lucian @ c:irua:91888 Serial 598
Permanent link to this record
 
 
Author Guttmann, P.; Bittencourt, C.; Ke, X.; Van Tendeloo, G.; Umek, P.; Arcon, D.; Ewels, C.P.; Rehbein, S.; Heim, S.; Schneider, G.
Title TXM-NEXAFS of TiO2-based nanostructures Type P1 Proceeding
Year 2011 Publication AIP conference proceedings Abbreviated Journal
Volume 1365 Issue Pages 437-440
Keywords P1 Proceeding; Electron microscopy for materials research (EMAT)
Abstract In this work, electronic properties of individual TiOx-pristine nanoribbons (NR) prepared by hydrothermal treatment of anatase TiO(2) micro-particles were studied using the HZB transmission x-ray microscope (TXM) at the BESSY II undulator beamline U41-FSGM. NEXAFS is ideally suited to study TiO(2)-based materials because both the O K-edge and Ti L-edge features are very sensitive to the local bonding environment, providing diagnostic information about the crystal structures and oxidation states of various forms of titanium oxides and sub-oxides. TXM-NEXAFS combines full-field x-ray microscopy with spectroscopy, allowing the study of the electronic structure of individual nanostructures with spatial resolution better than 25 nm and a spectral resolution of up to E/Delta E = 10000. The typical image field in TXM-NEXAFS measurements is about 10 mu m. 10 mu m, which is large compared to the individual nanoparticle. Therefore, one image stack already contains statistically significant data. In addition, the directional electric field vector ((E) over bar) of the x-rays can be used as a “search tool” for the direction of chemical bonds of the atom selected by its absorption edge.
Address
Corporate Author Thesis
Publisher Place of Publication New York Editor
Language Wos 000298672400103 Publication Date 2011-09-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor Times cited (up) 2 Open Access
Notes Approved Most recent IF: NA
Call Number UA @ lucian @ c:irua:113071 Serial 3789
Permanent link to this record
 
 
Author Tsoufis, T.; Georgakilas, V.; Ke, X.; Van Tendeloo, G.; Rudolf, P.; Gournis, D.
Title Incorporation of pure fullerene into organoclays : towards C60-pillared clay structures Type A1 Journal article
Year 2013 Publication Chemistry: a European journal Abbreviated Journal Chem-Eur J
Volume 19 Issue 24 Pages 7937-7943
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract In this work, we demonstrate the successful incorporation of pure fullerene from solution into two-dimensional layered aluminosilicate minerals. Pure fullerenes are insoluble in water and neutral in terms of charge, hence they cannot be introduced into the clay galleries by ion exchange or intercalation from water solution. To overcome this bottleneck, we organically modified the clay with quaternary amines by using well-established reactions in clay science in order to expand the interlayer space and render the galleries organophilic. During the reaction with the fullerene solution, the organic solvent could enter into the clay galleries, thus transferring along the fullerene molecules. Furthermore, we demonstrate that the surfactant molecules, can be selectively removed by either simple ion-exchange reaction (e.g., interaction with Al(NO3)3 solution to replace the surfactant molecules with Al3+ ions) or thermal treatment (heating at 350 °C) to obtain novel fullerene-pillared clay structures exhibiting enhanced surface area. The synthesized hybrid materials were characterized in detail by a combination of experimental techniques including powder X-ray diffraction, transmission electron microscopy, X-ray photoemission, and UV/Vis spectroscopy as well as thermal analysis and nitrogen adsorptiondesorption measurements. The reported fullerene-pillared clay structures constitute a new hybrid system with very promising potential for the use in areas such as gas storage and/or gas separation due to their high surface area.
Address
Corporate Author Thesis
Publisher Place of Publication Weinheim Editor
Language Wos 000319825500035 Publication Date 2013-04-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0947-6539; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 5.317 Times cited (up) 3 Open Access
Notes 262348 Esmi; 246791 Countatoms Approved Most recent IF: 5.317; 2013 IF: 5.696
Call Number UA @ lucian @ c:irua:107347 Serial 1599
Permanent link to this record
 
 
Author Chen, J.-J.; Ke, X.; Van Tendeloo, G.; Meng, J.; Zhou, Y.-B.; Liao, Z.-M.; Yu, D.-P.
Title Magnetotransport across the metal-graphene hybrid interface and its modulation by gate voltage Type A1 Journal article
Year 2015 Publication Nanoscale Abbreviated Journal Nanoscale
Volume 7 Issue 7 Pages 5516-5524
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract The graphene-metal contact is very important for optimizing the performance of graphene based electronic devices. However, it is difficult to probe the properties of the graphene/metal interface directly via transport measurements in traditional graphene lateral devices, because the dominated transport channel is graphene, not the interface. Here, we employ the Au/graphene/Au vertical and lateral hybrid structure to unveil the metal-graphene interface properties, where the transport is dominated by the charge carriers across the interface. The magnetoresistance (MR) of Au/monolayer graphene/Au and Au/stacked two-layered graphene/Au devices is measured and modulated by gate voltage, demonstrating that the interface is a device. The gate-tunable MR is identified from the graphene lying on the SiO2 substrate and underneath the top metal electrode. Our unique structures couple the in-plane and out-of-plane transport and display linear MR with small amplitude oscillations at low temperatures. Under a magnetic field, the electronic coupling between the graphene edge states and the electrode leads to the appearance of quantum oscillations. Our results not only provide a new pathway to explore the intrinsic transport mechanism at the graphene/metal interface but also open up new vistas of magnetoelectronics.
Address
Corporate Author Thesis
Publisher Place of Publication Cambridge Editor
Language Wos 000351372400050 Publication Date 2015-02-19
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2040-3364;2040-3372; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 7.367 Times cited (up) 3 Open Access
Notes 246791 Countatoms Approved Most recent IF: 7.367; 2015 IF: 7.394
Call Number c:irua:125533 Serial 1931
Permanent link to this record
 
 
Author Bittencourt, C.; Ke, X.; Van Tendeloo, G.; Tagmatarchis, N.; Guttmann, P.
Title NEXAFS spectromicroscopy of suspended carbon nanohorns Type A1 Journal article
Year 2013 Publication Chemical physics letters Abbreviated Journal Chem Phys Lett
Volume 587 Issue Pages 85-87
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We demonstrate that near-edge X-ray-absorption fine-structure spectroscopy combined with full-field transmission X-ray microscopy can be used to study the electronic structure of suspended carbon nanohorns. Based on reports of electronic structure calculations additional spectral features observed in the π region of the NEXAFS spectrum recorded on the carbon nanohorns were associated to the presence of the pentagonal rings and the folding of the graphene sheet.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000326104500016 Publication Date 2013-09-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0009-2614; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.815 Times cited (up) 4 Open Access
Notes Fp7; Countatoms; Approved Most recent IF: 1.815; 2013 IF: 1.991
Call Number UA @ lucian @ c:irua:111592 Serial 2339
Permanent link to this record
 
 
Author Hoek, M.; Coneri, F.; Poccia, N.; Renshaw Wang, X.; Ke, X.; Van Tendeloo, G.; Hilgenkamp, H.
Title Strain accommodation through facet matching in La1.85Sr0.15CuO4/Nd1.85Ce0.15CuO4 ramp-edge junctions Type A1 Journal article
Year 2015 Publication APL materials Abbreviated Journal Apl Mater
Volume 3 Issue 3 Pages 086101
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Scanning nano-focused X-ray diffraction and high-angle annular dark-field scanning transmission electron microscopy are used to investigate the crystal structure of ramp-edge junctions between superconducting electron-doped Nd1.85Ce0.15CuO4 and superconducting hole-doped La1.85Sr0.15CuO4 thin films, the latter being the top layer. On the ramp, a new growth mode of La1.85Sr0.15CuO4 with a 3.3° tilt of the c-axis is found. We explain the tilt by developing a strain accommodation model that relies on facet matching, dictated by the ramp angle, indicating that a coherent domain boundary is formed at the interface. The possible implications of this growth mode for the creation of artificial domains in morphotropic materials are discussed.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000360656800009 Publication Date 2015-08-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2166-532X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.335 Times cited (up) 4 Open Access
Notes 312483 Esteem2; 246791 Countatoms; esteem2_jra2 Approved Most recent IF: 4.335; 2015 IF: NA
Call Number c:irua:127690 c:irua:127690 Serial 3163
Permanent link to this record
 
 
Author Shan, L.; Punniyakoti, S.; Van Bael, M.J.; Temst, K.; Van Bael, M.K.; Ke, X.; Bals, S.; Van Tendeloo, G.; D'Olieslaeger, M.; Wagner, P.; Haenen, K.; Boyen, H.G.;
Title Homopolymers as nanocarriers for the loading of block copolymer micelles with metal salts : a facile way to large-scale ordered arrays of transition-metal nanoparticles Type A1 Journal article
Year 2014 Publication Journal of materials chemistry C : materials for optical and electronic devices Abbreviated Journal J Mater Chem C
Volume 2 Issue 4 Pages 701-707
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract A new and facile approach is presented for generating quasi-regular patterns of transition metal-based nanoparticles on flat substrates exploiting polystyrene-block-poly2vinyl pyridine (PS-b-P2VP) micelles as intermediate templates. Direct loading of such micellar nanoreactors by polar transition metal salts in solution usually results in nanoparticle ensembles exhibiting only short range order accompanied by broad distributions of particle size and inter-particle distance. Here, we demonstrate that the use of P2VP homopolymers of appropriate length as molecular carriers to transport precursor salts into the micellar cores can significantly increase the degree of lateral order within the final nanoparticle arrays combined with a decrease in spreading in particle size. Thus, a significantly extended range of materials is now available which can be exploited to study fundamental properties at the transition from clusters to solids by means of well-organized, well-separated, size-selected metal and metal oxide nanostructures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000329069900015 Publication Date 2013-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2050-7526;2050-7534; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 5.256 Times cited (up) 5 Open Access Not_Open_Access
Notes FWO projects G.0456.12; 50 G.0346.09N; Methusalem project "NANO Approved Most recent IF: 5.256; 2014 IF: 4.696
Call Number UA @ lucian @ c:irua:113734 Serial 1489
Permanent link to this record
 
 
Author Cabana, L.; Gonzalez-Campo, A.; Ke, X.; Van Tendeloo, G.; Nunez, R.; Tobias, G.
Title Efficient Chemical Modification of Carbon Nanotubes with Metallacarboranes Type A1 Journal article
Year 2015 Publication Chemistry: a European journal Abbreviated Journal Chem-Eur J
Volume 21 Issue 21 Pages 16792-16795
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract As-produced single-walled carbon nanotubes (SWCNTs) tend to aggregate in bundles due to pi-pi interactions. Several approaches are nowadays available to debundle, at least partially, the nanotubes through surface modification by both covalent and noncovalent approaches. Herein, we explore different strategies to afford an efficient covalent functionalization of SWCNTs with cobaltabisdicarbollide anions. Aberration-corrected HRTEM analysis reveals the presence of metallacarboranes along the walls of the SWCNTs. This new family of materials presents an outstanding water dispersibility that facilitates its processability for potential applications.
Address Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus Universitari de la UAB. 08193, Bellaterra (Spain). gerard.tobias@icmab.es
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000366501600011 Publication Date 2015-10-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0947-6539; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 5.317 Times cited (up) 5 Open Access
Notes The research leading to these results received financial support from MINECO (MAT2014-53500-R; CTQ2013-44670-R), Generalitat de Catalunya (2014/SGR/149), and from the European Commission under the FP7 ITN Marie-Curie Network programme RADDEL (grant agreement 290023), the Integrated Infrastructure Initiative No. 262348 European Soft Matter Infrastructure (ESMI) and the European Research Council, ERC Grant No 246791-COUNTATOMS. A.G.C. thanks the CSIC for the JAE-DOC grant. Approved Most recent IF: 5.317; 2015 IF: 5.731
Call Number c:irua:129215 Serial 3964
Permanent link to this record
 
 
Author Vereecke, B.; van der Veen, M.H.; Sugiura, M.; Kashiwagi, Y.; Ke, X.; Cott, D.J.; Hantschel, T.; Huyghebaert, C.; Tökei, Z.
Title Wafer-level electrical evaluation of vertical carbon nanotube bundles as a function of growth temperature Type A1 Journal article
Year 2013 Publication Japanese journal of applied physics Abbreviated Journal Jpn J Appl Phys
Volume 52 Issue 42 Pages 04cn02-5
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract We have evaluated the resistance of carbon nanotubes (CNTs) grown at a CMOS-compatible temperature using a realistic integration scheme. The structural analysis of the CNTs by transmission electron microscopy (TEM) showed that the degree of graphitization decreased significantly when the growth temperature was decreased from 540 to 400 °C. The CNTs were integrated to form 150-nm-diameter vertical interconnects between a TiN layer and Cu metal trenches on 200 mm full wafers. Wafers with CNTs grown at low temperature were found to have a lower single-contact resistance than those produced at high temperatures. Thickness measurements showed that the low contact resistance is a result of small contact height. This height dependence is masking the impact of CNT graphitization quality on resistance. When benchmarking our results with data from the literature, a relationship between resistivity and growth temperature cannot be found for CNT-based vertical interconnects.
Address
Corporate Author Thesis
Publisher Place of Publication Kyoto Editor
Language Wos 000320002400150 Publication Date 2013-03-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-4922;1347-4065; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.384 Times cited (up) 5 Open Access
Notes Approved Most recent IF: 1.384; 2013 IF: 1.057
Call Number UA @ lucian @ c:irua:108713 Serial 3902
Permanent link to this record
 
 
Author Vidick, D.; Ke, X.; Devillers, M.; Poleunis, C.; Delcorte, A.; Moggi, P.; Van Tendeloo, G.; Hermans, S.
Title Heterometal nanoparticles from Ru-based molecular clusters covalently anchored onto functionalized carbon nanotubes and nanofibers Type A1 Journal article
Year 2015 Publication Beilstein journal of nanotechnology Abbreviated Journal Beilstein J Nanotech
Volume 6 Issue 6 Pages 1287-1297
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Heterometal clusters containing Ru and Au, Co and/or Pt are anchored onto carbon nanotubes and nanofibers functionalized with chelating phosphine groups. The cluster anchoring yield is related to the amount of phosphine groups available on the nanocarbon surface. The ligands of the anchored molecular species are then removed by gentle thermal treatment in order to form nanoparticles. In the case of Au-containing clusters, removal of gold atoms from the clusters and agglomeration leads to a bimodal distribution of nanoparticles at the nanocarbon surface. In the case of Ru-Pt species, anchoring occurs without reorganization through a ligand exchange mechanism. After thermal treatment, ultrasmall (1-3 nm) bimetal Ru-Pt nanoparticles are formed on the surface of the nanocarbons. Characterization by high resolution transmission electron microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) confirms their bimetal nature on the nanoscale. The obtained bimetal nanoparticles supported on nanocarbon were tested as catalysts in ammonia synthesis and are shown to be active at low temperature and atmospheric pressure with very low Ru loading.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000355908400001 Publication Date 2015-06-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-4286; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.127 Times cited (up) 7 Open Access
Notes 246791 Countatoms; 262348 Esmi Approved Most recent IF: 3.127; 2015 IF: 2.670
Call Number c:irua:126431 Serial 1420
Permanent link to this record
 
 
Author Li, H.; Zhang, L.; Li, L.; Wu, C.; Huo, Y.; Chen, Y.; Liu, X.; Ke, X.; Luo, J.; Van Tendeloo, G.
Title Two-in-one solution using insect wings to produce graphene-graphite films for efficient electrocatalysis Type A1 Journal article
Year 2019 Publication Nano Research Abbreviated Journal Nano Res
Volume 12 Issue 1 Pages 33-39
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Natural organisms contain rich elements and naturally optimized smart structures, both of which have inspired various innovative concepts and designs in human society. In particular, several natural organisms have been used as element sources to synthesize low-cost and environmentally friendly electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells and metal-air batteries, which are clean energy devices. However, to date, no naturally optimized smart structures have been employed in the synthesis of ORR catalysts, including graphene-based materials. Here, we demonstrate a novel strategy to synthesize graphene-graphite films (GGFs) by heating butterfly wings coated with FeCl3 in N-2, in which the full power of natural organisms is utilized. The wings work not only as an element source for GGF generation but also as a porous supporting structure for effective nitrogen doping, two-dimensional spreading, and double-face exposure of the GGFs. These GGFs exhibit a half-wave potential of 0.942 V and a H2O2 yield of < 0.07% for ORR electrocatalysis; these values are comparable to those for the best commercial Pt/C and all previously reported ORR catalysts in alkaline media. This two-in-one strategy is also successful with cicada and dragonfly wings, indicating that it is a universal, green, and cost-effective method for developing high-performance graphene-based materials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000453629900004 Publication Date 2018-08-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1998-0124 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 7.354 Times cited (up) 7 Open Access Not_Open_Access
Notes ; The authors would like to thank Drs Qiang Wang and Wenjuan Yuan for useful discussions. This work was financially supported by the National Key R&D Program of China (No. 2017YFA0700104), the National Natural Science Foundation of China (Nos. 21601136 and 11404016), the National Program for Thousand Young Talents of China, Tianjin Municipal Education Commission, Tianjin Municipal Science and Technology Commission (No. 15JCYBJC52600), and the Fundamental Research Fund of Tianjin University of Technology. This work also made use of the resources of the National Center for Electron Microscopy in Beijing. ; Approved Most recent IF: 7.354
Call Number UA @ admin @ c:irua:156210 Serial 5265
Permanent link to this record
 
 
Author He, Z.; Ke, X.; Bals, S.; Van Tendeloo, G.
Title Direct evidence for the existence of multi-walled carbon nanotubes with hexagonal cross-sections Type A1 Journal article
Year 2012 Publication Carbon Abbreviated Journal Carbon
Volume 50 Issue 7 Pages 2524-2529
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Carbon nanotubes (CNTs) with a polygonal cross-section have been paid increasing attention since their three-dimensional structure is related to specific physical properties, which are found to be different in comparison to CNTs with a circular cross-section. Here, we report the existence of novel multi-walled CNTs yielding walls with a rounded-hexagonal configuration. This structure was directly confirmed for the first time by both cross-sectional transmission electron microscopy and electron tomography. The morphology of the Fe catalytic particle also exhibits hexagonal characteristics, and is proposed as the origin of the formation of the rounded-hexagonal walls of the CNT. This observation is of great importance with respect to the design of polygonal (such as pentagonal or hexagonal) cross-sectional CNTs. By controlling the morphology of the catalytic nanoparticles it will be possible to grow CNTs with desired electronic and mechanical properties.
Address
Corporate Author Thesis
Publisher Place of Publication Oxford Editor
Language Wos 000303038400015 Publication Date 2012-02-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0008-6223; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 6.337 Times cited (up) 8 Open Access
Notes Fwo Approved Most recent IF: 6.337; 2012 IF: 5.868
Call Number UA @ lucian @ c:irua:96956 Serial 711
Permanent link to this record
 
 
Author Ribbens, S.; Beyers, E.; Schellens, K.; Mertens, M.; Ke, X.; Bals, S.; Van Tendeloo, G.; Meynen, V.; Cool, P.
Title Systematic evaluation of thermal and mechanical stability of different commercial and synthetic photocatalysts in relation to their photocatalytic activity Type A1 Journal article
Year 2012 Publication Microporous and mesoporous materials: zeolites, clays, carbons and related materials Abbreviated Journal Micropor Mesopor Mat
Volume 156 Issue Pages 62-72
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Abstract The effect of thermal treatment and mechanical stress on the structural and photocatalytic properties of eight different (synthetic and commercial) photocatalysts has been thoroughly investigated. Different mesoporous Ti-based materials were prepared via surfactant based synthesis routes (e.g. Pluronic 123, CTMABr = Cetyltrimethylammonium bromide) or via template-free synthesis routes (e.g. trititanate nanotubes). Also, the stabilizing effect of the NaOH/NH4OH post-treatment on the templated mesoporous materials and their photocatalytic activity was investigated. Furthermore, the thermal and mechanical properties of commercially available titanium dioxides such as P25 Evonik® and Millenium PC500® were studied. The various photocatalysts were analyzed with N2-sorption, X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) to obtain information concerning the specific surface area, pore volume, crystal structure, morphology, phase transitions, etc. In general, results show that the NaOH post-treatment leads to an increased control of the crystallization process during calcination resulting in a higher thermal stability, but at the same time diminishes the photocatalytic activity. Mesoporous materials in which pre-synthesized nanoparticles are used as titania source have the best mechanical stability whereas the mechanical stability of the nanotubes is the most limited. At increased temperatures and pressures, the tested commercial titanium dioxides lose their superior photocatalytic activity caused by a decreased accessibility of the active sites. The observed changes in adsorption capacities and photocatalytic activities cannot be assigned to one single phenomenon. In this respect, it shows the need to define a general/standard method to compare different photocatalysts. Furthermore, it is shown that the photocatalytic properties do not necessarily deteriorate under thermal stress, but can be improved due to crystallization, even though the initial material is (partially) destroyed. It is shown that the usefulness of a specific type of photocatalyst strongly depends on the application and the temperature/pressure to which it needs to resist.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000303625200010 Publication Date 2012-02-08
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1387-1811; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.615 Times cited (up) 8 Open Access
Notes Fwo Approved Most recent IF: 3.615; 2012 IF: 3.365
Call Number UA @ lucian @ c:irua:96910 Serial 3466
Permanent link to this record
 
 
Author Li, J.; Pereira, P.J.; Yuan, J.; Lv, Y.-Y.; Jiang, M.-P.; Lu, D.; Lin, Z.-Q.; Liu, Y.-J.; Wang, J.-F.; Li, L.; Ke, X.; Van Tendeloo, G.; Li, M.-Y.; Feng, H.-L.; Hatano, T.; Wang, H.-B.; Wu, P.-H.; Yamaura, K.; Takayama-Muromachi, E.; Vanacken, J.; Chibotaru, L.F.; Moshchalkov, V.V.
Title Nematic superconducting state in iron pnictide superconductors Type A1 Journal article
Year 2017 Publication Nature communications Abbreviated Journal Nat Commun
Volume 8 Issue 1 Pages 1880
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Nematic order often breaks the tetragonal symmetry of iron-based superconductors. It arises from regular structural transition or electronic instability in the normal phase. Here, we report the observation of a nematic superconducting state, by measuring the angular dependence of the in-plane and out-of-plane magnetoresistivity of Ba 0.5 K 0.5 Fe 2 As 2 single crystals. We find large twofold oscillations in the vicinity of the superconducting transition, when the direction of applied magnetic field is rotated within the basal plane. To avoid the influences from sample geometry or current flow direction, the sample was designed as Corbino-shape for in-plane and mesa-shape for out-of-plane measurements. Theoretical analysis shows that the nematic superconductivity arises from the weak mixture of the quasi-degenerate s-wave and d-wave components of the superconducting condensate, most probably induced by a weak anisotropy of stresses inherent to single crystals.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000416933400002 Publication Date 2017-11-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2041-1723 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 12.124 Times cited (up) 8 Open Access OpenAccess
Notes The authors J.L., P.J.P., and J.Y. contributed equally to this work. J.L. and J.Y. designed the experiments. J.L., H.-L.F., K.Y., and E.T.-M. grew the single crystals. J.L., J.Y., Y.-Y.L., M.-P.J., D.L., M.-Y.L., T.H., H.-B.W., P.-H.W., K.Y., E.T.-M., J.V., and V.V.M. fabricated the devices and measured transport properties. J.L., Y.-Y.L., Z.-Q.L., Y.-J.L., J.-F.W., and L.L. studied on the pulsed high field measurements. X.K. and G.V.T. measured the low temperature TEM. All authors discussed the data. J.L., P.J.P., and L.F.C. proposed the model and simulated the results. J.L., P.J.P., K.Y., E.T.-M., and L.F.C. analyzed the data and prepared the manuscript. Approved Most recent IF: 12.124
Call Number EMAT @ emat @c:irua:147348 Serial 4772
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Author Song, H.-D.; Wu, Y.-F.; Yang, X.; Ren, Z.; Ke, X.; Kurttepeli, M.; Tendeloo, G.V.; Liu, D.; Wu, H.-C.; Yan, B.; Wu, X.; Duan, C.-G.; Han, G.; Liao, Z.-M.; Yu, D.
Title Asymmetric Modulation on Exchange Field in a Graphene/BiFeO3Heterostructure by External Magnetic Field Type A1 Journal article
Year 2018 Publication Nano letters Abbreviated Journal Nano Lett
Volume 18 Issue 4 Pages 2435-2441
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Graphene, having all atoms on its surface, is favorable to extend the functions by introducing the spin–orbit coupling and magnetism through proximity effect. Here, we report the tunable interfacial exchange field produced by proximity coupling in graphene/BiFeO3 heterostructures. The exchange field has a notable dependence with external magnetic field, and it is much larger under negative magnetic field than that under positive magnetic field. For negative external magnetic field, interfacial exchange coupling gives rise to evident spin splitting for N ≠ 0 Landau levels and a quantum Hall metal state for N = 0 Landau level. Our findings suggest graphene/BiFeO3 heterostructures are promising for spintronics.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000430155900034 Publication Date 2018-04-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1530-6984 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 12.712 Times cited (up) 9 Open Access Not_Open_Access
Notes This work was supported by National Key Research and Development Program of China (No. 2016YFA0300802) and NSFC (Nos. 11774004 and 11604004). Ministry of Science and Technology of the People's Republic of China, 2016YFA0300802 ; National Natural Science Foundation of China, 11604004 11774004 ; Approved Most recent IF: 12.712
Call Number EMAT @ lucian @c:irua:150794 Serial 4923
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Author Ke, X.; Bittencourt, C.; Van Tendeloo, G.
Title Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials Type A1 Journal article
Year 2015 Publication Beilstein journal of nanotechnology Abbreviated Journal Beilstein J Nanotech
Volume 6 Issue 6 Pages 1541-1557
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract A major revolution for electron microscopy in the past decade is the introduction of aberration correction, which enables one to increase both the spatial resolution and the energy resolution to the optical limit. Aberration correction has contributed significantly to the imaging at low operating voltages. This is crucial for carbon-based nanomaterials which are sensitive to electron irradiation. The research of carbon nanomaterials and nanohybrids, in particular the fundamental understanding of defects and interfaces, can now be carried out in unprecedented detail by aberration-corrected transmission electron microscopy (AC-TEM). This review discusses new possibilities and limits of AC-TEM at low voltage, including the structural imaging at atomic resolution, in three dimensions and spectroscopic investigation of chemistry and bonding. In situ TEM of carbon-based nanomaterials is discussed and illustrated through recent reports with particular emphasis on the underlying physics of interactions between electrons and carbon atoms.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000357977300001 Publication Date 2015-07-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-4286; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.127 Times cited (up) 10 Open Access
Notes 246791 Countatoms Approved Most recent IF: 3.127; 2015 IF: 2.670
Call Number c:irua:126857 Serial 2682
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Author Chen, J.J.; Wang, Q.; Meng, J.; Ke, X.; Van Tendeloo, G.; Bie, Y.Q.; Liu, J.; Liu, K.; Liao, Z.M.; Sun, D.; Yu, D.;
Title Photovoltaic effect and evidence of carrier multiplication in graphene vertical homojunctions with asymmetrical metal contacts Type A1 Journal article
Year 2015 Publication ACS nano Abbreviated Journal Acs Nano
Volume 9 Issue 9 Pages 8851-8858
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Graphene exhibits exciting potentials for high-speed wideband photodetection and high quantum efficiency solar energy harvest because of its broad spectral absorption, fast photoelectric response, and potential carrier multiplication. Although photocurrent can be generated near a metalgraphene interface in lateral devices, the photoactive area is usually limited to a tiny one-dimensional line-like interface region. Here, we report photoelectric devices based on vertical graphene two-dimensional homojunction, which is fabricated via vertically stacking four graphene monolayers with asymmetric metal contacts. The devices show excellent photovoltaic output with excitation wavelength ranging from visible light to mid-infrared. The wavelength dependence of the internal quantum efficiency gives direct evidence of the carrier multiplication effect in graphene. The simple fabrication process, easy scale-up, large photoresponsive active area, and broadband response of the vertical graphene device are very promising for practical applications in optoelectronics and photovoltaics.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000361935800023 Publication Date 2015-08-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1936-0851;1936-086X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 13.942 Times cited (up) 11 Open Access
Notes 246791 Countatoms Approved Most recent IF: 13.942; 2015 IF: 12.881
Call Number c:irua:127689 Serial 2615
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Author Li, J.; Ji, M.; Schwarz, T.; Ke, X.; Van Tendeloo, G.; Yuan, J.; Pereira, P.J.; Huang, Y.; Zhang, G.; Feng, H.L.; Yuan, Y.H.; Hatano, T.; Kleiner, R.; Koelle, D.; Chibotaru, L.F.; Yamaura, K.; Wang, H.B.; Wu, P.H.; Takayama-Muromachi, E.; Vanacken, J.; Moshchalkov, V.V.;
Title Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors Type A1 Journal article
Year 2015 Publication Nature communications Abbreviated Journal Nat Commun
Volume 6 Issue 6 Pages 7614
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract The determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional Swiss cheese-like pattern with in-plane and out-of-plane characteristic lengths slightly below ~1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000358857000007 Publication Date 2015-07-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2041-1723; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 12.124 Times cited (up) 12 Open Access
Notes 246791 Countatoms Approved Most recent IF: 12.124; 2015 IF: 11.470
Call Number c:irua:126677 Serial 1827
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Author Ke, X.; Bittencourt, C.; Bals, S.; Van Tendeloo, G.
Title Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM Type A1 Journal article
Year 2013 Publication Beilstein journal of nanotechnology Abbreviated Journal Beilstein J Nanotech
Volume 4 Issue Pages 77-86
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Focused-electron-beam-induced deposition (FEBID) is used as a direct-write approach to decorate ultrasmall Pt nanoclusters on carbon nanotubes at selected sites in a straightforward maskless manner. The as-deposited nanostructures are studied by transmission electron microscopy (TEM) in 2D and 3D, demonstrating that the Pt nanoclusters are well-dispersed, covering the selected areas of the CNT surface completely. The ability of FEBID to graft nanoclusters on multiple sides, through an electron-transparent target within one step, is unique as a physical deposition method. Using high-resolution TEM we have shown that the CNT structure can be well preserved thanks to the low dose used in FEBID. By tuning the electron-beam parameters, the density and distribution of the nanoclusters can be controlled. The purity of as-deposited nanoclusters can be improved by low-energy electron irradiation at room temperature.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000314499700001 Publication Date 2013-02-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-4286; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.127 Times cited (up) 12 Open Access
Notes 262348 ESMI; 246791 COUNTATOMS; FWO G002410N; ESF Cost Action NanoTP MP0901 Approved Most recent IF: 3.127; 2013 IF: 2.332
Call Number UA @ lucian @ c:irua:106187 Serial 1848
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Author Zhang, L.; Lin, B.-C.; Wu, Y.-F.; Wu, H.; Huang, T.-W.; Chang, C.-R.; Ke, X.; Kurttepeli, M.; Tendeloo, G.V.; Xu, J.; Yu, D.; Liao, Z.-M.
Title Electronic Coupling between Graphene and Topological Insulator Induced Anomalous Magnetotransport Properties Type A1 Journal article
Year 2017 Publication ACS nano Abbreviated Journal Acs Nano
Volume 11 Issue 11 Pages 6277-6285
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract It has been theoretically proposed that the spin textures of surface states in a topological insulator can be directly transferred to graphene by means of the proximity effect, which is very important for realizing the two-dimensional topological insulator based on graphene. Here we report the anomalous magnetotransport properties of graphene-topological insulator Bi2Se3 heterojunctions, which are sensitive to the electronic coupling between graphene and the topological surface state. The coupling between the p_z orbitals of graphene and the p orbitals of the surface states on the Bi2Se3 bottom surface can be enhanced by applying a perpendicular negative magnetic field, resulting in a giant negative magnetoresistance at the Dirac point up to about -91%. Obvious resistances dip in the transfer curve at the Dirac point is also observed in the hybrid devices, which is consistent with theoretical predictions of the distorted Dirac bands with nontrivial spin textures inherited from the Bi2Se3 surface states.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000404808000110 Publication Date 2017-05-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1936-0851 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 13.942 Times cited (up) 12 Open Access OpenAccess
Notes ; This work was supported by National Key Research and Development Program of China (Nos. 2016YFA0300802, 2013CB934600) and NSFC (No. 11234001). ; Approved Most recent IF: 13.942
Call Number EMAT @ emat @ c:irua:143192 Serial 4569
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Author Bittencourt, C.; Krüger, P.; Lagos, M.J.; Ke, X.; Van Tendeloo, G.; Ewels, C.; Umek, P.; Guttmann, P.
Title Towards atomic resolution in sodium titanate nanotubes using near-edge X-ray-absorption fine-structure spectromicroscopy combined with multichannel multiple-scattering calculations Type A1 Journal article
Year 2012 Publication Beilstein journal of nanotechnology Abbreviated Journal Beilstein J Nanotech
Volume 3 Issue Pages 789-797
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Recent advances in near-edge X-ray-absorption fine-structure spectroscopy coupled with transmission X-ray microscopy (NEXAFS-TXM) allow large-area mapping investigations of individual nano-objects with spectral resolution up to E/Delta E = 104 and spatial resolution approaching 10 nm. While the state-of-the-art spatial resolution of X-ray microscopy is limited by nanostructuring process constrains of the objective zone plate, we show here that it is possible to overcome this through close coupling with high-level theoretical modelling. Taking the example of isolated bundles of hydrothermally prepared sodium titanate nanotubes ((Na,H)TiNTs) we are able to unravel the complex nanoscale structure from the NEXAFS-TXM data using multichannel multiple-scattering calculations, to the extent of being able to associate specific spectral features in the O K-edge and Ti L-edge with oxygen atoms in distinct sites within the lattice. These can even be distinguished from the contribution of different hydroxyl groups to the electronic structure of the (Na,H)TiNTs.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000311482400001 Publication Date 2012-11-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-4286; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.127 Times cited (up) 13 Open Access
Notes Approved Most recent IF: 3.127; 2012 IF: 2.374
Call Number UA @ lucian @ c:irua:105140 Serial 3684
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Author Zhong, R.; Peng, L.; de Clippel, F.; Gommes, C.; Goderis, B.; Ke, X.; Van Tendeloo, G.; Jacobs, P.A.; Sels, B.F.
Title An eco-friendly soft template synthesis of mesostructured silica-carbon nanocomposites for acid catalysis Type A1 Journal article
Year 2015 Publication ChemCatChem Abbreviated Journal Chemcatchem
Volume 7 Issue 7 Pages 3047-3058
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The synthesis of ordered mesoporous silica-carbon composites was explored by employing TEOS and sucrose as the silica and carbon precursor respectively, and the triblock copolymer F127 as a structure-directing agent via an evaporation-induced self-assembly (EISA) process. It is demonstrated that the synthesis procedures allow for control of the textural properties and final composition of these silica-carbon nanocomposites via adjustment of the effective SiO2/C weight ratio. Characterization by SAXS, N-2 physisorption, HRTEM, TGA, and C-13 and Si-29 solid-state MAS NMR show a 2D hexagonal mesostructure with uniform large pore size ranging from 5.2 to 7.6nm, comprising of separate carbon phases in a continuous silica phase. Ordered mesoporous silica and non-ordered porous carbon can be obtained by combustion of the pyrolyzed nanocomposites in air or etching with HF solution, respectively. Sulfonic acid groups can be readily introduced to such kind of silica-carbon nanocomposites by a standard sulfonation procedure with concentrated sulfuric acid. Excellent acid-catalytic activities and selectivities for the dimerization of styrene to produce 1,3-diphenyl-1-butene and dimerization of -methylstyrene to unsaturated dimers were demonstrated with the sulfonated materials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000361189400037 Publication Date 2015-09-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1867-3880; 1867-3899 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 4.803 Times cited (up) 13 Open Access
Notes Approved Most recent IF: 4.803; 2015 IF: 4.556
Call Number UA @ lucian @ c:irua:127836 Serial 4138
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Author Yan, Y.; Zhou, X.; Jin, H.; Li, C.-Z.; Ke, X.; Van Tendeloo, G.; Liu, K.; Yu, D.; Dressel, M.; Liao, Z.-M.
Title Surface-Facet-Dependent Phonon Deformation Potential in Individual Strained Topological Insulator Bi2Se3 Nanoribbons Type A1 Journal article
Year 2015 Publication ACS nano Abbreviated Journal Acs Nano
Volume 9 Issue 9 Pages 10244-10251
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Strain is an important method to tune the properties of topological insulators. For example, compressive strain can induce superconductivity in Bi2Se3 bulk material. Topological insulator nanostructures are the superior candidates to utilize the unique surface states due to the large surface to volume ratio. Therefore, it is highly desirable to monitor the local strain effects in individual topological insulator nanostructures. Here, we report the systematical micro-Raman spectra of single strained Bi2Se3 nanoribbons with different thicknesses and different surface facets, where four optical modes are resolved in both Stokes and anti-Stokes Raman spectral lines. A striking anisotropy of the strain dependence is observed in the phonon frequency of strained Bi2Se3 nanoribbons grown along the ⟨112̅0⟩ direction. The frequencies of the in-plane Eg2 and out-of-plane A1g1 modes exhibit a nearly linear blue-shift against bending strain when the nanoribbon is bent along the ⟨112̅0⟩ direction with the curved {0001} surface. In this case, the phonon deformation potential of the Eg2 phonon for 100 nm-thick Bi2Se3 nanoribbon is up to 0.94 cm–1/%, which is twice of that in Bi2Se3 bulk material (0.52 cm–1/%). Our results may be valuable for the strain modulation of individual topological insulator nanostructures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Wos 000363915300079 Publication Date 2015-09-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1936-0851;1936-086X; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 13.942 Times cited (up) 14 Open Access
Notes Y.Y. would like to thank Xuewen Fu for helpful discussions. This work was supported by MOST (Nos. 2013CB934600, 2013CB932602) and NSFC (Nos. 11274014, 11234001). Approved Most recent IF: 13.942; 2015 IF: 12.881
Call Number c:irua:129216 Serial 3963
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Author Bittencourt, C.; van Lier, G.; Ke, X.; Suarez-Martinez, I.; Felten, A.; Ghijsen, J.; Van Tendeloo, G.; Ewels, C.O.
Title Spectroscopy and defect identification for fluorinated carbon nanotubes Type A1 Journal article
Year 2009 Publication ChemPhysChem : a European journal of chemical physics and physical chemistry Abbreviated Journal Chemphyschem
Volume 10 Issue 6 Pages 920-925
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Multi-wall carbon nanotubes (MWCNTs) were exposed to a CF4 radio-frequency (rf) plasma. High-resolution photoelectron spectroscopy shows that the treatment effectively grafts fluorine atoms onto the MWCNTs, altering the valence electronic states. Fluorine surface concentration can be tuned by varying the exposure time. Evaporation of gold onto MWCNTs is used to mark active site formation. High-resolution transmission electron microscopy coupled with density functional theory (DFT) modelling is used to characterise the surface defects formed, indicating that the plasma treatment does not etch the tube surface. We suggest that this combination of theory and microscopy of thermally evaporated gold atoms onto the CNT surface may be a powerful approach to characterise both surface defect density as well as defect type.
Address
Corporate Author Thesis
Publisher Place of Publication Weinheim Editor
Language Wos 000265469200011 Publication Date 2009-03-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1439-4235;1439-7641; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.075 Times cited (up) 14 Open Access
Notes Iuap; Fwo Approved Most recent IF: 3.075; 2009 IF: 3.453
Call Number UA @ lucian @ c:irua:77315 Serial 3073
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Author de Clippel, F.; Harkiolakis, A.; Vosch, T.; Ke, X.; Giebeler, L.; Oswald, S.; Houthoofd, K.; Jammaer, J.; Van Tendeloo, G.; Martens, J.A.; Jacobs, P.A.; Baron, G.V.; Sels, B.F.; Denayer, J.F.M.
Title Graphitic nanocrystals inside the pores of mesoporous silica : synthesis, characterization and an adsorption study Type A1 Journal article
Year 2011 Publication Microporous and mesoporous materials: zeolites, clays, carbons and related materials Abbreviated Journal Micropor Mesopor Mat
Volume 144 Issue 1/3 Pages 120-133
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract This work presents a new carbonsilica hybrid material, denoted as CSM, with remarkable sorption properties. It consists of intraporous graphitic nanocrystals grown in the pores of mesoporous silica. CSM is obtained by a subtle incipient wetness impregnation of Al-containing mesoporous silica with furfuryl alcohol (FA)/hemelitol solutions. Both the volume match of the impregnation solution with that of the silica template pore volume, and the presence of Al3+ in the silica, are crucial to polymerize FA selectively inside the mesopores. Carbonization of the intraporous polymer was then performed by pyrolysis under He up to 1273 K. The resulting CSMs were examined by SEM, HRTEM, 27Al MAS NMR, N2 adsorption, XRD, TGA, TPD, XPS, pycnometry and Raman spectroscopy. Mildly oxidized graphitic-like carbon nanoblocks, consisting of a few graphene-like sheets, were thus identified inside the template mesopores. Random stacking of these carbon crystallites generates microporosity resulting in biporous materials at low carbon content and microporous materials at high carbon loadings. Very narrow pore distributions were obtained when pyrolysis was carried out under slow heating rate, viz. 1 K min−1. Adsorption and shape selective properties of the carbon filled mesoporous silica were studied by performing pulse chromatography and breakthrough experiments, and by measuring adsorption isotherms of linear and branched alkanes. Whereas the parent mesoporous silica shows unselective adsorption, their CSM analogues preferentially adsorb linear alkanes. The sorption capacity and selectivity can be adjusted by changing the pore size of the template or by varying the synthesis conditions. A relation between the carbon crystallites size and the shape selective behaviour of the corresponding CSM for instance is demonstrated. Most interestingly, CSM shows separation factors for linear and branched alkanes up to values comparable to those of zeolitic molecular sieves.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000293435400016 Publication Date 2011-04-15
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1387-1811; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.615 Times cited (up) 15 Open Access
Notes Approved Most recent IF: 3.615; 2011 IF: 3.285
Call Number UA @ lucian @ c:irua:92325 Serial 1380
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Author Bittencourt, C.; Hitchock, A.P.; Ke, X.; Van Tendeloo, G.; Ewels, C.P.; Guttmann, P.
Title X-ray absorption spectroscopy by full-field X-ray microscopy of a thin graphite flake: Imaging and electronic structure via the carbon K-edge Type A1 Journal article
Year 2012 Publication Beilstein journal of nanotechnology Abbreviated Journal Beilstein J Nanotech
Volume 3 Issue Pages 345-350
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract We demonstrate that near-edge X-ray-absorption fine-structure spectra combined with full-field transmission X-ray microscopy can be used to study the electronic structure of graphite flakes consisting of a few graphene layers. The flake was produced by exfoliation using sodium cholate and then isolated by means of density-gradient ultracentrifugation. An image sequence around the carbon K-edge, analyzed by using reference spectra for the in-plane and out-of-plane regions of the sample, is used to map and spectrally characterize the flat and folded regions of the flake. Additional spectral features in both π and σ regions are observed, which may be related to the presence of topological defects. Doping by metal impurities that were present in the original exfoliated graphite is indicated by the presence of a pre-edge signal at 284.2 eV.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000303243400001 Publication Date 2012-04-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2190-4286; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.127 Times cited (up) 15 Open Access
Notes Approved Most recent IF: 3.127; 2012 IF: 2.374
Call Number UA @ lucian @ c:irua:97703 Serial 3924
Permanent link to this record
 
 
Author Ke, X.; Turner, S.; Quintana, M.; Hadad, C.; Montellano-López, A.; Carraro, M.; Sartorel, A.; Bonchio, M.; Prato, M.; Bittencourt, C.; Van Tendeloo, G.;
Title Dynamic motion of Ru-polyoxometalate ions (POMs) on functionalized few-layer graphene Type A1 Journal article
Year 2013 Publication Small Abbreviated Journal Small
Volume 9 Issue 23 Pages 3922-3927
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract The interaction and stability of Ru4POM on few layer graphene via functional groups is investigated by time-dependent imaging using aberration-corrected transmission electron microscopy. The Ru4POM demonstrates dynamic motion on the graphene surface with its frequency and amplitude of rotation related to the nature of the functional group used. The stability of the Ru4POMgraphene hybrid corroborates its long-term robustness when applied to multielectronic catalytic processes.
Address
Corporate Author Thesis
Publisher Place of Publication Weinheim Editor
Language Wos 000331282400003 Publication Date 2013-07-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1613-6810; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.643 Times cited (up) 16 Open Access
Notes IAP-7; Countatoms; Approved Most recent IF: 8.643; 2013 IF: 7.514
Call Number UA @ lucian @ c:irua:115768 Serial 763
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Author Gengler, R.Y.N.; Toma, L.M.; Pardo, E.; Lloret, F.; Ke, X.; Van Tendeloo, G.; Gournis, D.; Rudolf, P.
Title Prussian blue analogues of reduced dimensionality Type A1 Journal article
Year 2012 Publication Small Abbreviated Journal Small
Volume 8 Issue 16 Pages 2532-2540
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Abstract Mixed-valence polycyanides (Prussian Blue analogues) possess a rich palette of properties spanning from room-temperature ferromagnetism to zero thermal expansion, which can be tuned by chemical modifications or the application of external stimuli (temperature, pressure, light irradiation). While molecule-based materials can combine physical and chemical properties associated with molecular-scale building blocks, their successful integration into real devices depends primarily on higher-order properties such as crystal size, shape, morphology, and organization. Herein a study of a new reduced-dimensionality system based on Prussian Blue analogues (PBAs) is presented. The system is built up by means of a modified Langmuir-Blodgett technique, where the PBA is synthesized from precursors in a self-limited reaction on a clay mineral surface. The focus of this work is understanding the magnetic properties of the PBAs in different periodic, low-dimensional arrangements, and the influence of the “on surface” synthesis on the final properties and dimensionality of the system.
Address
Corporate Author Thesis
Publisher Place of Publication Weinheim Editor
Language Wos 000307390300012 Publication Date 2012-07-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1613-6810; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 8.643 Times cited (up) 17 Open Access
Notes Approved Most recent IF: 8.643; 2012 IF: 7.823
Call Number UA @ lucian @ c:irua:101104 Serial 2736
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