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	Author	Sheath, B.C.; Xu, X.; Manuel, P.; Hadermann, J.; Batuk, M.; O'Sullivan, J.; Bonilla, R.S.; Clarke, S.J.
	Title	Structures and magnetic ordering in layered Cr oxide arsenides Sr₂CrO₂Cr₂OAs₂ and Sr₂CrO₃CrAs			Type	A1 Journal article
	Year	2022	Publication	Inorganic chemistry	Abbreviated Journal	Inorg Chem
	Volume	61	Issue	31	Pages	10-12385
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Two novel chromium oxide arsenide materials have been synthesized, Sr2CrO2Cr2OAs2 (i.e., Sr2Cr3As2O3) and Sr2CrO3CrAs (i.e., Sr2Cr2AsO3), both of which contain chromium ions in two distinct layers. Sr2CrO2Cr2OAs2 was targeted following electron microscopy measurements on a related phase. It crystallizes in the space group P4/mmm and accommodates distorted CrO4As2 octahedra containing Cr2+ and distorted CrO(2)As(4 )octahedra containing Cr3+. In contrast, Sr2CrO3CrAs incorporates Cr3+ in CrO5 square-pyramidal coordination in [Sr2CrO3](+) layers and Cr2+ ions in CrAs(4 )tetrahedra in [CrAs](-) layers and crystallizes in the space group P4/nmm. Powder neutron diffraction data reveal antiferromagnetic ordering in both compounds. In Sr2CrO3CrAs the Cr2+ moments in the [CrAs](-) layers exhibit long-range ordering, while the Cr3+ moments in the [Sr2CrO3](+) layers only exhibit short-range ordering. However, in Sr2CrO2Cr2OAs2, both the Cr(2+ )moments in the CrO4As2 environments and the Cr3+ moments in the CrO2As4 polyhedra are long-range-ordered below 530(10) K. Above this temperature, only the Cr3+ moments are ordered with a Neel temperature slightly in excess of 600 K. A subtle structural change is evident in Sr2CrO2Cr2OAs2 below the magnetic ordering transitions.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000841943600001	Publication Date	2022-07-27
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0020-1669	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.6	Times cited		Open Access	OpenAccess
	Notes				Approved	Most recent IF: 4.6
	Call Number	UA @ admin @ c:irua:190007			Serial	7215
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	Author	Yi, Y.; Li, S.; Cui, Z.; Hao, Y.; Zhang, Y.; Wang, L.; Liu, P.; Tu, X.; Xu, X.; Guo, H.; Bogaerts, A.
	Title	Selective oxidation of CH4 to CH3OH through plasma catalysis: Insights from catalyst characterization and chemical kinetics modelling			Type	A1 Journal Article;Methane conversion
	Year	2021	Publication	Applied Catalysis B-Environmental	Abbreviated Journal	Appl Catal B-Environ
	Volume	296	Issue		Pages	120384
	Keywords	A1 Journal Article;Methane conversion; Plasma catalysis; Selective oxidation; Methanol synthesis; Plasma chemistry; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
	Abstract	The selective oxidation of methane to methanol (SOMTM) by molecular oxygen is a holy grail in catalytic chemistry and remains a challenge in chemical industry. We perform SOMTM in a CH4/O2 plasma, at low temperature and atmospheric pressure, promoted by Ni-based catalysts, reaching 81 % liquid oxygenates selectivity and 50 % CH3OH selectivity, with an excellent catalytic stability. Chemical kinetics modelling shows that CH3OH in the plasma is mainly produced through radical reactions, i.e., CH4 + O(1D) → CH3O + H, followed by CH3O + H + M→ CH3OH + M and CH3O + HCO → CH3OH + CO. The catalyst characterization shows that the improved production of CH3OH is attributed to abundant chemisorbed oxygen species, originating from highly dispersed NiO phase with strong oxide support interaction with γ-Al2O3, which are capable of promoting CH3OH formation through E-R reactions and activating H2O molecules to facilitate CH3OH desorption.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000706860000003	Publication Date	2021-05-21
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0926-3373	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	9.446	Times cited		Open Access	OpenAccess
	Notes	National Natural Science Foundation of China; PetroChina Innovation Foundation; We acknowledge financial support from the PetroChina Innovation Foundation [grant ID: 2018D-5007-0501], the Young Star Project of Dalian Science and Technology Bureau [grant ID: 2019RQ042], the National Natural Science Foundation of China [grant ID: 21503032] and the TOP research project of the Research Fund of the University of Antwerp [grant ID: 32249].			Approved	Most recent IF: 9.446
	Call Number	PLASMANT @ plasmant @c:irua:178816			Serial	6793
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	Author	Xu, X.; Jones, M.A.; Cassidy, S.J.; Manuel, P.; Orlandi, F.; Batuk, M.; Hadermann, J.; Clarke, S.J.
	Title	Magnetic Ordering in the Layered Cr(II) Oxide Arsenides Sr₂CrO₂Cr₂As₂and Ba₂CrO₂Cr₂As₂			Type	A1 Journal article
	Year	2020	Publication	Inorganic Chemistry	Abbreviated Journal	Inorg Chem
	Volume	59	Issue	21	Pages	15898-15912
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT)
	Abstract	Sr2CrO2Cr2As2 and Ba2CrO2Cr2As2 with Cr2+ ions in CrO2 sheets and in CrAs layers crystallize with the Sr2Mn3Sb2O2 structure (space group I4/mmm, Z = 2) and lattice parameters a = 4.00800(2) Å, c = 18.8214(1) Å (Sr2CrO2Cr2As2) and a = 4.05506(2) Å, c = 20.5637(1) Å (Ba2CrO2Cr2As2) at room temperature. Powder neutron diffraction reveals checkerboard-type antiferromagnetic ordering of the Cr2+ ions in the arsenide layers below TN1Sr, of 600(10) K (Sr2CrO2Cr2As2) and TN1Ba 465(5) K (Ba2CrO2Cr2As2) with the moments initially directed perpendicular to the layers in both compounds. Checkerboard-type antiferromagnetic ordering of the Cr2+ ions in the oxide layer below 230(5) K for Ba2CrO2Cr2As2 occurs with these moments also perpendicular to the layers, consistent with the orientation preferences of d4 moments in the two layers. In contrast, below 330(5) K in Sr2CrO2Cr2As2, the oxide layer Cr2+ moments are initially oriented in the CrO2 plane; but on further cooling, these moments rotate to become perpendicular to the CrO2 planes, while the moments in the arsenide layers rotate by 90° with the moments on the two sublattices remaining orthogonal throughout [behavior recently reported independently by Liu et al. [Liu et al. Phys. Rev. B 2018, 98, 134416]]. In Sr2CrO2Cr2As2, electron diffraction and high resolution powder X-ray diffraction data show no evidence for a structural distortion that would allow the two Cr2+ sublattices to couple, but high resolution neutron powder diffraction data suggest a small incommensurability between the magnetic structure and the crystal structure, which may account for the coupling of the two sublattices and the observed spin reorientation. The saturation values of the Cr2+ moments in the CrO2 layers (3.34(1) μB (for Sr2CrO2Cr2As2) and 3.30(1) μB (for Ba2CrO2Cr2As2)) are larger than those in the CrAs layers (2.68(1) μB for Sr2CrO2Cr2As2 and 2.298(8) μB for Ba2CrO2Cr2As2) reflecting greater covalency in the arsenide layers.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000588738100035	Publication Date	2020-11-02
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0020-1669	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	4.6	Times cited		Open Access	OpenAccess
	Notes	We thank the UK EPSRC (EP/M020517/1 and EP/P018874/ 1) and the Leverhulme Trust (RPG-2014-221) for funding and the ISIS pulsed neutron and muon source (RB1610357 and RB1700075) and the Diamond Light Source Ltd. (EE13284 and EE18786) for the award of beam time. We thank Dr. A. Baker and Dr. C. Murray for support on I11.			Approved	Most recent IF: 4.6; 2020 IF: 4.857
	Call Number	EMAT @ emat @c:irua:176058			Serial	6704
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	Author	Xu, X.; Vereecke, G.; Chen, C.; Pourtois, G.; Armini, S.; Verellen, N.; Tsai, W.K.; Kim, D.W.; Lee, E.; Lin, C.Y.; Van Dorpe, P.; Struyf, H.; Holsteyns, F.; Moshchalkov, V.; Indekeu, J.; De Gendt, S.;
	Title	Capturing wetting states in nanopatterned silicon			Type	A1 Journal article
	Year	2014	Publication	ACS nano	Abbreviated Journal	Acs Nano
	Volume	8	Issue	1	Pages	885-893
	Keywords	A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
	Abstract	Spectacular progress in developing advanced Si circuits with reduced size, along the track of Moore's law, has been relying on necessary developments in wet cleaning of nanopatterned Si wafers to provide contaminant free surfaces. The most efficient cleaning is achieved when complete wetting can be realized. In this work, ordered arrays of silicon nanopillars on a hitherto unexplored small scale have been used to study the wetting behavior on nanomodulated surfaces in a substantial range of surface treatments and geometrical parameters. With the use of optical reflectance measurements, the nanoscale water imbibition depths have been measured and the transition to the superhydrophobic Cassie-Baxter state has been accurately determined. For pillars of high aspect ratio (about 15), the transition occurs even when the surface is grafted with a hydrophilic functional group. We have found a striking consistent deviation between the contact angle measurements and the straightforward application of the classical wetting models. Molecular dynamics simulations show that these deviations can be attributed to the long overlooked atomic-scale surface perturbations that are introduced during the nanofabrication process. When the transition condition is approached, transient states of partial imbibition that characterize intermediate states between the Wenzel and Cassie-Baxter states are revealed in our experiments.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000330542900092	Publication Date	2013-12-31
	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	39	Open Access
	Notes				Approved	Most recent IF: 13.942; 2014 IF: 12.881
	Call Number	UA @ lucian @ c:irua:114871			Serial	276
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	Author	Zhang, Y.-R.; Xu, X.; Bogaerts, A.; Wang, Y.-N.
	Title	Fluid simulation of the phase-shift effect in hydrogen capacitively coupled plasmas: 1 : transient behaviour of electrodynamics and power deposition			Type	A1 Journal article
	Year	2012	Publication	Journal of physics: D: applied physics	Abbreviated Journal	J Phys D Appl Phys
	Volume	45	Issue	1	Pages	015202-015202,11
	Keywords	A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
	Abstract	A two-dimensional self-consistent fluid model coupled with the full set of Maxwell equations is established to investigate the phase-shift effect on the transient behaviour of electrodynamics and power deposition in a hydrogen capacitively coupled plasma. The effect has been examined at 13.56 MHz and 100 MHz, respectively, because of the different phase-shift modulation when the electromagnetic effects are dominant. The results indicate that the spatiotemporal distributions of the plasma characteristics obtained for various phase-shift cases are obviously different both in shape and especially in absolute values. Indeed, when the phase difference varies from 0 to π, there is an increase in the electron flux, thus the power deposition becomes more pronounced. At the frequency of 13.56 MHz, the axial electron flux in the bulk plasma becomes uniform along the z-axis, and the radial electron flux exhibits two peaks within one period at the reverse-phase case, whereas the oscillation is less pronounced at the in-phase case. Furthermore, in the very high frequency discharge, the radial electron flux is alternately positive and negative with four peaks during one period, and the ionization mainly occurs in the sheath region, due to the prominent power deposition there at a phase difference equal to π.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000298290000011	Publication Date	2011-12-12
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0022-3727;1361-6463;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.588	Times cited	57	Open Access
	Notes				Approved	Most recent IF: 2.588; 2012 IF: 2.528
	Call Number	UA @ lucian @ c:irua:92851			Serial	1230
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	Author	Zhang, Y.-R.; Xu, X.; Bogaerts, A.; Wang, Y.-N.
	Title	Fluid simulation of the phase-shift effect in hydrogen capacitively coupled plasmas: 2 : radial uniformity of the plasma characteristics			Type	A1 Journal article
	Year	2012	Publication	Journal of physics: D: applied physics	Abbreviated Journal	J Phys D Appl Phys
	Volume	45	Issue	1	Pages	015203-015203,13
	Keywords	A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
	Abstract	A two-dimensional fluid model, including the full set of Maxwell equations, has been developed and applied to investigate the effect of a phase shift between two power sources on the radial uniformity of several plasma characteristics in a hydrogen capacitively coupled plasma. This study was carried out at various frequencies in the range 13.56200 MHz. When the frequency is low, at 13.56 MHz, the plasma density is characterized by an off-axis peak when both power sources are in-phase (phgr = 0), and the best radial uniformity is obtained at phgr = π. This trend can be explained because the radial nonuniformity caused by the electrostatic edge effect can be effectively suppressed by the phase-shift effect at a phase difference equal to π. When the frequency rises to 60 MHz, the plasma density profiles shift smoothly from edge-peaked over uniform to centre-peaked as the phase difference increases, due to the pronounced standing-wave effect, and the best radial uniformity is reached at phgr = 0.3π. At a frequency of 100 MHz, a similar behaviour is observed, except that the maximum of the plasma density moves again towards the radial edge at the reverse-phase case (phgr = π), because of the dominant skin effect. When the frequency is 200 MHz, the bulk plasma density increases significantly with increasing phase-shift values, and a better uniformity is obtained at phgr = 0.4π. This is because the density in the centre increases faster than at the radial edge as the phase difference rises, due to the increasing power deposition Pz in the centre and the decreasing power density Pr at the radial edge. As the phase difference increases to π, the maximum near the radial edge becomes obvious again. This is because the skin effect has a predominant influence on the plasma density under this condition, resulting in a high density at the radial edge. Moreover, the axial ion flux increases monotonically with phase difference, and exhibits similar profiles to the plasma density. The calculation results illustrate that the radial uniformity of the various plasma characteristics is strongly dependent on the applied frequency and the phase shift between both power sources, which is important to realize, for controlling the uniformity of the plasma etch and deposition processes.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	London	Editor
	Language		Wos	000298290000012	Publication Date	2011-12-12
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0022-3727;1361-6463;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.588	Times cited	15	Open Access
	Notes				Approved	Most recent IF: 2.588; 2012 IF: 2.528
	Call Number	UA @ lucian @ c:irua:92852			Serial	1231
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	Author	Si, X.-J.; Zhao, S.-X.; Xu, X.; Bogaerts, A.; Wang, Y.-N.
	Title	Fluid simulations of frequency effects on nonlinear harmonics in inductively coupled plasma			Type	A1 Journal article
	Year	2011	Publication	Physics of plasmas	Abbreviated Journal	Phys Plasmas
	Volume	18	Issue	3	Pages	033504-033504,9
	Keywords	A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
	Abstract	A fluid model is self-consistently established to investigate the harmonic effects in an inductively coupled plasma, where the electromagnetic field is solved by the finite difference time domain technique. The spatiotemporal distribution of harmonic current density, harmonic potential, and other plasma quantities, such as radio frequency power deposition, plasma density, and electron temperature, have been investigated. Distinct differences in current density have been observed when calculated with and without Lorentz force, which indicates that the nonlinear Lorentz force plays an important role in the harmonic effects, especially at low frequencies. Moreover, the even harmonics are larger than the odd harmonics both in the current density and the potential. Finally, the dependence of various plasma quantities with and without the Lorentz force on various driving frequencies is also examined. It is shown that the deposited power density decreases and the depth of penetration increases slightly because of the Lorentz force. The electron density increases distinctly while the electron temperature remains almost the same when the Lorentz force is taken into account.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Woodbury, N.Y.	Editor
	Language		Wos	000289151900073	Publication Date	2011-03-18
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1070-664X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.115	Times cited	7	Open Access
	Notes				Approved	Most recent IF: 2.115; 2011 IF: 2.147
	Call Number	UA @ lucian @ c:irua:87876			Serial	1233
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	Author	Zhang, Y.-R.; Xu, X.; Zhao, S.-X.; Bogaerts, A.; Wang, Y.-N.
	Title	Comparison of electrostatic and electromagnetic simulations for very high frequency plasmas			Type	A1 Journal article
	Year	2010	Publication	Physics of plasmas	Abbreviated Journal	Phys Plasmas
	Volume	17	Issue	11	Pages	113512-113512,11
	Keywords	A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
	Abstract	A two-dimensional self-consistent fluid model combined with the full set of Maxwell equations is developed to investigate an argon capacitively coupled plasma, focusing on the electromagnetic effects on the discharge characteristics at various discharge conditions. The results indicate that there exist distinct differences in plasma characteristics calculated with the so-called electrostatic model (i.e., without taking into account the electromagnetic effects) and the electromagnetic model (which includes the electromagnetic effects), especially at very high frequencies. Indeed, when the excitation source is in the high frequency regime and the electromagnetic effects are taken into account, the plasma density increases significantly and meanwhile the ionization rate evolves to a very different distribution when the electromagnetic effects are dominant. Furthermore, the dependence of the plasma characteristics on the voltage and pressure is also investigated, at constant frequency. It is observed that when the voltage is low, the difference between these two models becomes more obvious than at higher voltages. As the pressure increases, the plasma density profiles obtained from the electromagnetic model smoothly shift from edge-peaked over uniform to a broad maximum in the center. In addition, the edge effect becomes less pronounced with increasing frequency and pressure, and the skin effect rather than the standing-wave effect becomes dominant when the voltage is high.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Woodbury, N.Y.	Editor
	Language		Wos	000285486500105	Publication Date	2010-11-22
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1070-664X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.115	Times cited	30	Open Access
	Notes				Approved	Most recent IF: 2.115; 2010 IF: 2.320
	Call Number	UA @ lucian @ c:irua:84763			Serial	429
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