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Author Mulder, J.T.T.; Jenkinson, K.; Toso, S.; Prato, M.; Evers, W.H.H.; Bals, S.; Manna, L.; Houtepen, A.J.J. url  doi
openurl 
  Title Nucleation and growth of bipyramidal Yb:LiYF₄ nanocrystals : growing up in a hot environment Type A1 Journal article
  Year (down) 2023 Publication Chemistry of materials Abbreviated Journal  
  Volume 35 Issue 14 Pages 5311-5321  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract Lanthanide-doped LiYF4 (Ln:YLF) is commonlyused fora broad variety of optical applications, such as lasing, photon upconversionand optical refrigeration. When synthesized as nanocrystals (NCs),this material is also of interest for biological applications andfundamental physical studies. Until now, it was unclear how Ln:YLFNCs grow from their ionic precursors into tetragonal NCs with a well-defined,bipyramidal shape and uniform dopant distribution. Here, we studythe nucleation and growth of ytterbium-doped LiYF4 (Yb:YLF),as a template for general Ln:YLF NC syntheses. We show that the formationof bipyramidal Yb:YLF NCs is a multistep process starting with theformation of amorphous Yb:YLF spheres. Over time, these spheres growvia Ostwald ripening and crystallize, resulting in bipyramidal Yb:YLFNCs. We further show that prolonged heating of the NCs results inthe degradation of the NCs, observed by the presence of large LiFcubes and small, irregular Yb:YLF NCs. Due to the similarity in chemicalnature of all lanthanide ions our work sheds light on the formationstages of Ln:YLF NCs in general.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 001021474500001 Publication Date 2023-07-03  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0897-4756; 1520-5002 ISBN Additional Links UA library record; WoS full record  
  Impact Factor 8.6 Times cited Open Access OpenAccess  
  Notes This project has received funding from the European Union's Horizon 2020 research and innovation program under Grant Agreement No. 766900 (Testing the large-scale limit of quantum mechanics). The authors thank Niranjan Saikumar for proof reading the manuscript. Approved Most recent IF: 8.6; 2023 IF: 9.466  
  Call Number UA @ admin @ c:irua:197787 Serial 8907  
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Author Geuchies, J.J.; van Overbeek, C.; Evers, W.H.; Goris, B.; de Backer, A.; Gantapara, A.P.; Rabouw, F.T.; Hilhorst, J.; Peters, J.L.; Konovalov, O.; Petukhov, A.V.; Dijkstra, M.; Siebbeles, L.D.A.; van Aert, S.; Bals, S.; Vanmaekelbergh, D. url  doi
openurl 
  Title In situ study of the formation mechanism of two-dimensional superlattices from PbSe nanocrystals Type A1 Journal article
  Year (down) 2016 Publication Nature materials Abbreviated Journal Nat Mater  
  Volume 15 Issue 15 Pages 1248-1254  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract Oriented attachment of PbSe nanocubes can result in the formation of two-dimensional (2D) superstructures with long-range nanoscale and atomic order. This questions the applicability of classic models in which the superlattice grows by first forming a nucleus, followed by sequential irreversible attachment of nanocrystals, as one misaligned attachment would disrupt the 2D order beyond repair. Here, we demonstrate the formation mechanism of 2D PbSe superstructures with square geometry by using in situ grazing-incidence X-ray scattering (small angle and wide angle), ex situ electron microscopy, and Monte Carlo simulations. We observed nanocrystal adsorption at the liquid/gas interface, followed by the formation of a hexagonal nanocrystal monolayer. The hexagonal geometry transforms gradually through a pseudo-hexagonal phase into a phase with square order, driven by attractive interactions between the {100} planes perpendicular to the liquid substrate, which maximize facet-to-facet overlap. The nanocrystals then attach atomically via a necking process, resulting in 2D square superlattices.  
  Address Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3584 CC Utrecht, The Netherlands  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language English Wos 000389104400011 Publication Date 2016-09-05  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1476-1122 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 39.737 Times cited 182 Open Access OpenAccess  
  Notes This research is part of the programme ‘Designing Dirac Carriers in semiconductor honeycomb superlattices (DDC13),’ which is supported by the Foundation for Fundamental Research on Matter (FOM), which is part of the Dutch Research Council (NWO). J.J.G. acknowledges funding from the Debye and ESRF Graduate Programs. The authors gratefully acknowledge funding from the Research Foundation Flanders (G.036915 G.037413 and funding of postdoctoral grants to B.G. and A.d.B). S.B. acknowledges the European Research Council, ERC grant No 335078—Colouratom. The authors gratefully acknowledge I. Swart and M. van Huis for fruitful discussions. We acknowledge funding from NWO-CW TOPPUNT ‘Superficial Superstructures’. The X-ray scattering measurements were performed at the ID10 beamline at ESRF under proposal numbers SC-4125 and SC-3786. The authors thank G. L. Destri and F. Zontone for their support during the experiments.; ECAS_Sara; (ROMEO:yellow; preprint:; postprint:restricted ; pdfversion:cannot); Approved Most recent IF: 39.737  
  Call Number EMAT @ emat @ c:irua:136165 Serial 4289  
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Author Boneschanscher, M.P.; Evers, W.H.; Geuchies, J.J.; Altantzis, T.; Goris, B.; Rabouw, F.T.; van Rossum, S.A.P.; van der Zant, H.S.J.; Siebbeles, L.D.A.; Van Tendeloo, G.; Swart, I.; Hilhorst, J.; Petukhov, A.V.; Bals, S.; Vanmaekelbergh, D.; pdf  url
doi  openurl
  Title Long-range orientation and atomic attachment of nanocrystals in 2D honeycomb superlattices Type A1 Journal article
  Year (down) 2014 Publication Science Abbreviated Journal Science  
  Volume 344 Issue 6190 Pages 1377-1380  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Oriented attachment of synthetic semiconductor nanocrystals is emerging as a route for obtaining new semiconductors that can have Dirac-type electronic bands like graphene, but also strong spin-orbit coupling. The two-dimensional assembly geometry will require both atomic coherence and long-range periodicity of the superlattices. We show how the interfacial self-assembly and oriented attachment of nanocrystals results in two-dimensional (2D) metal chalcogenide semiconductors with a honeycomb superlattice. We present an extensive atomic and nanoscale characterization of these systems using direct imaging and wave scattering methods. The honeycomb superlattices are atomically coherent, and have an octahedral symmetry that is buckled; the nanocrystals occupy two parallel planes. Considerable necking and large-scale atomic motion occurred during the attachment process.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Washington, D.C. Editor  
  Language Wos 000337531700035 Publication Date 2014-05-30  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0036-8075;1095-9203; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 37.205 Times cited 304 Open Access OpenAccess  
  Notes Fwo; 262348 Esmi; 246791 Countatoms; 335078 Colouratom; ECAS_Sara; (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); Approved Most recent IF: 37.205; 2014 IF: 33.611  
  Call Number UA @ lucian @ c:irua:117095 Serial 1840  
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Author Kalesaki, E.; Boneschanscher, M.P.; Geuchies, J.J.; Delerue, C.; Morais Smith, C.; Evers, W.H.; Allan, G.; Altantzis, T.; Bals, S.; Vanmaekelbergh, D. pdf  url
doi  openurl
  Title Preparation and study of 2-D semiconductors with Dirac type bands due to the honeycomb nanogeometry Type P1 Proceeding
  Year (down) 2014 Publication Proceedings of the Society of Photo-optical Instrumentation Engineers T2 – Proceedings of SPIE Abbreviated Journal  
  Volume 8981 Issue Pages 898107-898107  
  Keywords P1 Proceeding; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract The interest in 2-dimensional systems with a honeycomb lattice and related Dirac-­type electronic bands has exceeded the prototype graphene1. Currently, 2-­dimensional atomic2,3 and nanoscale4-­8 systems are extensively investigated in the search for materials with novel electronic properties that can be tailored by geometry. The immediate question that arises is how to fabricate 2-­D semiconductors that have a honeycomb nanogeometry, and as a consequence of that, display a Dirac-­type band structure? Here, we show that atomically coherent honeycomb superlattices of rocksalt (PbSe, PbTe) and zincblende (CdSe, CdTe) semiconductors can be obtained by nanocrystal self-­assembly and facet-­to-­facet atomic bonding, and subsequent cation exchange. We present a extended structural analysis of atomically coherent 2-­D honeycomb structures that were recently obtained with self-assembly and facet-­to-­facet bonding9. We show that this process may in principle lead to three different types of honeycomb structures, one with a graphene type-­, and two others with a silicene-­type structure. Using TEM, electron diffraction, STM and GISAXS it is convincingly shown that the structures are from the silicene-­type. In the second part of this work, we describe the electronic structure of graphene-­type and silicene type honeycomb semiconductors. We present the results of advanced electronic structure calculations using the sp3d5s* atomistic tight-­binding method10. For simplicity, we focus on semiconductors with a simple and single conduction band for the native bulk semiconductor. When the 3-­D geometry is changed into 2-­D honeycomb, a conduction band structure transformation to two types of Dirac cones, one for S-­ and one for P-­orbitals, is observed. The width of the bands depends on the honeycomb period and the coupling between the nanocrystals. Furthermore, there is a dispersionless P-­orbital band, which also forms a landmark of the honeycomb structure. The effects of considerable intrinsic spin-­orbit coupling are briefly considered. For heavy-­element compounds such as CdTe, strong intrinsic spin-­‐orbit coupling opens a non-­trivial gap at the P-­orbital Dirac point, leading to a quantum Spin Hall effect10-­12. Our work shows that well known semiconductor crystals, known for centuries, can lead to systems with entirely new electronic properties, by the simple action of nanogeometry. It can be foreseen that such structures will play a key role in future opto-­electronic applications, provided that they can be fabricated in a straightforward way.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000336040600004 Publication Date 2014-03-07  
  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 2 Open Access OpenAccess  
  Notes This work has been supported by funding of the French National Research Agency [ANR, (ANR-­‐09-­‐BLAN-­‐0421-­‐01)], NWO and the Dutch organization FOM [Programs “Control over Functional Nanoparticle Solids” (FNPS) and “Designing Dirac Carriers in Semiconductors” Approved Most recent IF: NA  
  Call Number c:irua:131912 Serial 4039  
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Author Evers, W.H.; Goris, B.; Bals, S.; Casavola, M.; de Graaf, J.; van Roij, R.; Dijkstra, M.; Vanmaekelbergh, D. pdf  url
doi  openurl
  Title Low-dimensional semiconductor superlattices formed by geometric control over nanocrystal attachment Type A1 Journal article
  Year (down) 2013 Publication Nano letters Abbreviated Journal Nano Lett  
  Volume 13 Issue 6 Pages 2317-2323  
  Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)  
  Abstract Oriented attachment, the process in which nanometer-sized crystals fuse by atomic bonding of specific crystal facets, is expected to be more difficult to control than nanocrystal self-assembly that is driven by entropic factors or weak van der Waals attractions. Here, we present a study of oriented attachment of PbSe nanocrystals that counteract this tuition. The reaction was studied in a thin film of the suspension casted on an immiscible liquid at a given temperature. We report that attachment can be controlled such that it occurs with one type of facets exclusively. By control of the temperature and particle concentration we obtain one- or two-dimensional PbSe single crystals, the latter with a honeycomb or square superimposed periodicity in the nanometer range. We demonstrate the ability to convert these PbSe superstructures into other semiconductor compounds with the preservation of crystallinity and geometry.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Washington Editor  
  Language Wos 000320485100001 Publication Date 2012-10-11  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1530-6984;1530-6992; ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 12.712 Times cited 206 Open Access  
  Notes 262348 ESMI; Hercules 3 Approved Most recent IF: 12.712; 2013 IF: 12.940  
  Call Number UA @ lucian @ c:irua:101777 Serial 1847  
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Author Grodzińska, D.; Evers, W.H.; Dorland, R.; van Rijssel, J.; van Huis, M.A.; Meijerink, A.; de Mello Donegá, C.; Vanmaekelbergh, D. doi  openurl
  Title Two-fold emission from the S-shell of PbSe/CdSe core/shell quantum dots Type A1 Journal article
  Year (down) 2011 Publication Small Abbreviated Journal Small  
  Volume 7 Issue 24 Pages 3493-3501  
  Keywords A1 Journal article; Electron microscopy for materials research (EMAT)  
  Abstract The optical properties of PbSe/CdSe core/shell quantum dots with core sizes smaller than 4 nm in the 5300 K range are reported. The photoluminescence spectra show two peaks, which become increasingly separated in energy as the core diameter is reduced below 4 nm. It is shown that these peaks are due to intrinsic exciton transitions in each quantum dot, rather than emission from different quantum dot sub-ensembles. Most likely, the energy separation between the peaks is due to inter-valley coupling between the L-points of PbSe. The temperature dependence of the relative intensities of the peaks implies that the two emitting states are not in thermal equilibrium and that dark exciton states must play an important role.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Weinheim Editor  
  Language Wos 000298298300012 Publication Date 2011-10-21  
  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 23 Open Access  
  Notes Approved Most recent IF: 8.643; 2011 IF: 8.349  
  Call Number UA @ lucian @ c:irua:94371 Serial 3781  
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