scholarly journals XXIV Международный симпозиум Нанофизика и наноэлектроника", Нижний Новгород, 10-13 марта 2020 г. Изменение кристаллической фазы в гетероструктурных Ga(As, P) нитевидных нанокристаллах под воздействием упругих напряжений

2020 ◽  
Vol 54 (10) ◽  
pp. 1117
Author(s):  
Н.В. Сибирев ◽  
Ю.С. Бердников ◽  
В.Н. Сибирев
Keyword(s):  
Crystal Structure ◽  
Elastic Strain ◽  
Metastable Phase ◽  
Crystal Phase ◽  
Phase Switching ◽  
Stable Growth

In this work, the influence of elastic strain on Ga(As,P) nanowire crystal structure was studied. The stable growth of nanowire in the metastable phase is explained by accounting the elastic strain in the nucleus of newly-forming nanowire layer. Within this approach, the crystal phase switching in GaP nanowire after Ga(AsP) insertion is explained.

scholarly journals Роль упругих напряжений при формировании нитридных нитевидных нанокристаллов с кубической кристаллической структурой

2019 ◽  
Vol 45 (20) ◽  
pp. 39
Author(s):  
Н.В. Сибирев ◽  
Ю.С. Бердников ◽  
В.Н. Сибирев
Keyword(s):  
Crystal Structure ◽  
Elastic Strain ◽  
Theoretical Study ◽  
Crystal Phase ◽  
Cubic Crystal ◽  
Cubic Lattice ◽  
Gan Nanowires ◽  
Sapphire Substrates

In this work, a theoretical study of the growth of nitride nanowires with metastable cubic (zincblende) crystal structure is presented. The formation of cubic lattice is explained by accounting the elastic strain in the nucleus of a new layer within the nanowire. The growth of GaN nanowires with cubic crystal phase on sapphire substrates is described.

Crystal Structure Control of ZnxCd1−xS Alloyed Nanocrystals and Structural Dependent Fluorescence Properties

NANO ◽  
2019 ◽  
Vol 14 (08) ◽  
pp. 1950098
Author(s):  
Kaili Qin ◽  
Jingling Li ◽  
Yanqing Zhu ◽  
Xueqing Xu ◽  
Xiudi Xiao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Phase ◽  
Fluorescence Properties ◽  
Pure Zinc ◽  
Structure Control ◽  
Zinc Blende ◽  
Coating Method ◽  
Ratio Condition ◽  
One Step ◽  
Zinc Blende Structure

Crystal structure control is so important to the fluorescence properties that each element should be considered carefully. In conventional synthesis of ZnxCd[Formula: see text]S alloyed nanocrystals (NCs), most of studies focus on ligand–surface interaction on the formation of either zinc blende or wurtzite ZnxCd[Formula: see text]S nanocrystals, instead of the reactant source. In this work, mixed crystal phase was found easily in ZnxCd[Formula: see text]S alloyed NCs when reaction proceeded at high Zn/Cd source ratio condition. Therefore, we regulate the Zn/Cd ratio to obtain relative pure zinc-blende structure, and study the influence of structure change on the fluorescence properties. Further, we have proposed a two-step ZnS coating method to acquire ZnxCd[Formula: see text]S/ZnS NCs with separated crystal-phase between core and shell. Compared with maximum QY of 81% for ZnxCd[Formula: see text]S/ZnS NCs synthesized by conventional one-step coating method, the performance of the optimized NCs has significantly improved with maximum QY of 93%.

Antiferroelectric Liquid Crystals from Achiral Molecules And A Liquid Conglomerate

1999 ◽  
Vol 559 ◽  
Author(s):  
David M. Walba ◽  
Eva Körblova ◽  
Renfan Shao ◽  
Joseph E. Maclennan ◽  
Darren R. Link ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Crystal Phase ◽  
Liquid Crystal Phase ◽  
Crystalline Structures ◽  
Chiral Liquid Crystal ◽  
Antiferroelectric Liquid Crystals ◽  
Liquid Crystal Structure

ABSTRACTUntil recently, it was an empirical fact that creation of a chiral liquid crystal phase required enantiomerically enriched molecules. In addition, to date known ferroelectric and antiferroelectric smectics have also been composed of enantiomerically enriched molecules. Herein are described the first examples of the formation of chiral and antiferroelectric supermolecular liquid crystalline structures from achiral molecules. In one case (apparently metastable) the liquid crystal structure is macroscopically chiral, with samples composed of heterochiral macroscopic domains: a liquid conglomerate.

Crystal structures, defects and transformations in the Al-(Fe,Mn)-Si alloy system

1990 ◽  
Vol 48 (4) ◽  
pp. 956-957
Author(s):  
V. Hansen ◽  
P. Skjerpe ◽  
J. Gjønnes
Keyword(s):  
Crystal Structure ◽  
Metastable Phase ◽  
Stacking Faults ◽  
Alloy System ◽  
Direct Chill ◽  
Strip Casting ◽  
Secondary Particles ◽  
Primary Particles ◽  
Stable And Metastable Phases

The alloy system Al-Fe,Mn-Si is attracting interest because of its tendency to produce quasicrystals. It is also of considerable importance in alloy technology Recent studies have in fact shown that precipitation of icosahedral particles may be the first step in the formation of secondary particles during treatment of Mn-containing alloys produced by strip-casting (Hansen, Gjønnes and Andersson 1989).Our studies of the system have been governed partly by the industrial interest They include several stable and metastable phases which appear in commercial alloys produced by direct chill- (DC-) or strip-casting. Both primary and secondary particles are studied. Especially for the metastable particles electron diffraction and microscopy is essential for determination of crystal structure as well as of defect arrangement.Previous studies included twins and stacking faults in primary particles of AL3Fe and derivation of a structure proposal for the tetragonal metastable phase AlmFe by diffraction and imaging.

Electronic Structure Changes Due to Crystal Phase Switching at the Atomic Scale Limit

ACS Nano ◽  
2017 ◽  
Vol 11 (10) ◽  
pp. 10519-10528 ◽  
Author(s):  
Johan Valentin Knutsson ◽  
Sebastian Lehmann ◽  
Martin Hjort ◽  
Edvin Lundgren ◽  
Kimberly A. Dick ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Atomic Scale ◽  
Crystal Phase ◽  
Phase Switching ◽  
Structure Changes ◽  
Scale Limit

The Crystal Structure of Pressure-Induced Phases of In2Te3and Ga2Te3

1992 ◽  
Vol 7 (2) ◽  
pp. 99-102 ◽  
Author(s):  
N.R. Serebryanaya
Keyword(s):  
Crystal Structure ◽  
Metastable Phase ◽  
Face Centered Cubic ◽  
Volume Changes ◽  
X Ray ◽  
The Face ◽  
Crystal Structure Transformation ◽  
Face Centered ◽  
Heating Up

AbstractPhase transitions were found with use of an in situX-ray anvil-type of apparatus with a boron annulus at pressures up to 12 GPa. The disordering of vacancies in the In sub-structure, or α→βtransition, was found in In2Te3at p > 1.9 GPa. The next transformation from the β-form into the Bi2Te3type of structure was observed in both sesquitellurides at 2.0 GPa and 5.0 GPa for In2TGe3and Ga2Te3respectively. The In2Te3metastable phase of the Bi2Te3resulted from heating up to 200° C at p > 4.0 GPa, and it remained in a normal condition on release of the pressure. The X-ray powder diffraction data of pressure-induced phases, volume changes and bulk modulus of both sesquitellurides are given. The compressibility anisotropy of the layer pressure-induced phase was observed. The mechanism of the crystal structure transformation from the face-centered cubic structure into the Bi2Te3type is proposed to be due to the displacement of atoms from the space diagonal of the cube [111] into [112]-cubic direction and the rhombohedral distortion of the angle between these directions.

The crystal structure of monoclinic CaAl2Si2O8: a case of monoclinic structure closely simulating orthorhombic symmetry

1973 ◽  
Vol 137 (5-6) ◽  
Author(s):  
Y. Takéuchi ◽  
N. Haga ◽  
J. Ito
Keyword(s):  
Crystal Structure ◽  
Metastable Phase ◽  
Orthorhombic Symmetry ◽  
Monoclinic Structure

AbstractA monoclinic metastable phase of anorthite composition, CaAlThere is no evidence that the synthetic “orthorhombic CaAl

scholarly journals Structural response of α-quartz under plate-impact shock compression

2020 ◽  
Vol 6 (35) ◽  
pp. eabb3913
Author(s):  
Sally June Tracy ◽  
Stefan J. Turneaure ◽  
Thomas S. Duffy
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Shock Compression ◽  
Materials Science ◽  
Metastable Phase ◽  
Dynamic Compression ◽  
Phase Region ◽  
High Pressure Phase ◽  
Gas Gun ◽  
Pressure Phase

Because of its far-reaching applications in geophysics and materials science, quartz has been one of the most extensively examined materials under dynamic compression. Despite 50 years of active research, questions remain concerning the structure and transformation of SiO2 under shock compression. Continuum gas-gun studies have established that under shock loading quartz transforms through an assumed mixed-phase region to a dense high-pressure phase. While it has often been assumed that this high-pressure phase corresponds to the stishovite structure observed in static experiments, there have been no crystal structure data confirming this. In this study, we use gas-gun shock compression coupled with in situ synchrotron x-ray diffraction to interrogate the crystal structure of shock-compressed α-quartz up to 65 GPa. Our results reveal that α-quartz undergoes a phase transformation to a disordered metastable phase as opposed to crystalline stishovite or an amorphous structure, challenging long-standing assumptions about the dynamic response of this fundamental material.

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