Phase Transformations in Lutetium Borides at Heating in Vacuum

2011 ◽  
Vol 172-174 ◽  
pp. 464-469 ◽  
Author(s):  
Anatoliy Taran ◽  
Daniel Voronovich ◽  
Natalya Shitsevalova ◽  
Ganna Levchenko ◽  
Volodymyr Filipov ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Transformation ◽  
Surface Layer ◽  
Single Crystal ◽  
Phase Transformations ◽  
Single Crystals ◽  
X Ray ◽  
Before And After ◽  
Spontaneous Phase ◽  
Crystal Bulk

The LuB12 ® LuB4 ® LuB2 phase transformations on annealing in vacuum (T=(1400÷1800) K, p < 10-2 Pa) are investigated with use of the parent single crystals. SEM and X-ray researches of the corresponding lutetium boride single crystals were carried out before and after their annealing. It is shown that the LuB12 → LuB4 phase transformation takes place in surface layer and transition region spreads inwards the single crystal bulk with time. According to the assessed Lu-B phase diagram the LuB4 phase transformation into other individual phases is impossible, and at first it is shown that under corresponding conditions the LuB4 → LuB2 spontaneous phase transformation takes place both on the surface and in the LuB4 single crystal bulk.

scholarly journals Crystal structure, homogeneity range and electronic structure of rhombohedral γ-Mn5Al8

2017 ◽  
Vol 232 (7-9) ◽  
Author(s):  
Srinivasa Thimmaiah ◽  
Zachary Tener ◽  
Tej N. Lamichhane ◽  
Paul C. Canfield ◽  
Gordon J. Miller
Keyword(s):  
Crystal Structure ◽  
Phase Diagram ◽  
Electronic Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Homogeneity Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Eds Analysis

AbstractThe γ-region of the Mn–Al phase diagram between 45 and 70 at.% Al was re-investigated by a combination of powder and single crystal X-ray diffraction as well as EDS analysis to establish the distribution of Mn and Al atoms. Single crystals of γ-Mn

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

scholarly journals Modeling of magneto-conductivity of bismuth selenide: a topological insulator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Field Range ◽  
X Ray ◽  
Bulk Carriers ◽  
Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

Calcium Carbodiimide Compounds Revisited – Syntheses, Single Crystal Structure Determination and Vibrational Spectra of Ca11N6[CN2]2, Ca4N2[CN2] and Ca[CN2]

2008 ◽  
Vol 63 (5) ◽  
pp. 530-536 ◽  
Author(s):  
Olaf Reckeweg ◽  
Francis J. DiSalvo
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Single Crystal ◽  
Single Crystals ◽  
Vibrational Spectra ◽  
Structure Determination ◽  
X Ray ◽  
Characteristic Features ◽  
Reported Data ◽  
Correct Data

Single crystals of Ca11N6[CN2]2 (dark red needles, tetragonal, P42/mnm (no. 136), a = 1456.22(5), and c = 361.86(2) pm, Z = 2), Ca4N2[CN2] (transparent yellow needles, orthorhombic, Pnma (no. 62), a = 1146.51(11), b = 358.33(4), and c = 1385.77(13) pm, Z = 4) and Ca[CN2] (transparent, colorless, triangular plates, rhombohedral, R3̅m (no. 166), a = 369.00(3), and c = 1477.5(3) pm, Z = 3) were obtained by the reaction of Na2[CN2], CaCl2 and Ca3N2 (if demanded by stoichiometry) in arc-welded Ta ampoules at temperatures between 1200 - 1400 K. Their crystal structures were re-determined by means of single crystal X-ray structure analyses. Additionally, the Raman spectra were recorded on these same single crystals, whereas the IR spectra were obtained with the KBr pellet technique. The title compounds exhibit characteristic features for carbodiimide units with D∞h symmetry (d(C-N) = 121.7 - 123.8 pm and ∡ (N-C-N) = 180°). The vibrational frequencies of these units are in the expected range (Ca11N6[CN2]2: νs = 1230, νs = 2008; δ = 673/645/624 cm−1; Ca4N2[CN2]: νs = 1230, νs = 1986; δ = 672/647 cm−1; Ca[CN2]: νs = 1274, νs = 2031, δ = 668 cm−1). The structural results are more precise than the previously reported data, and with the newly attained Raman spectrum of Ca11N6[CN2]2 we correct data reported earlier.

scholarly journals Discontinuities at the melting point of bismuth

1931 ◽  
Vol 133 (821) ◽  
pp. 162-172 ◽  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Random Distribution ◽  
Grown Crystal ◽  
Perfect Crystal ◽  
Real Property ◽  
Resistance Change ◽  
X Ray ◽  
Almost All ◽  
Brittle Crystals

During the last two or three years considerable attention has been given to the growth of single crystals of bismuth and to their physical properties. The result of this work has shown that the preparation of a good single crystal is exceedingly difficult, the process being easily disturbed in many ways, and the conclusion must be drawn that it has not yet been possible to obtain anything approaching a perfect crystal. In all cases where the grown crystal has been adequately examined, it has been necessary to admit that the supposed single crystal was full of discontinuities. This was shown by Kapitza* in his work on the growth and magneto­-resistance change of single crystals of bismuth. He found it very difficult to produce a crystal rod parallel to the hexagonal axis that was flexible. Almost all the crystals grown with this orientation were apparently brittle in that a very little strain would cause a sharp fracture parallel to the principal cleavage plane. Some crystals indeed broke up into small pieces 2 or 3 mm. long when dropped from a height of a few centimetres on a table. As the separate pieces proved to be fairly flexible this brittleness is not a real property of the crystal, but appears to be due to isolated cracks or discontinuities in the crystal (the word “crack” is used with the meaning defined by Kapitza in his paper, where further arguments for their existence from X-ray and resistance measurements are given). These cracks are not characteristic only of the brittle crystals, but appear to be present in many flexible crystals as well, their flexibility being due to a random distribution of a comparatively large number of cracks small in area compared to the dimensions of the rod.

Insight into microstructural and phase transformations in electrochemical sodiation–desodiation of a bismuth particulate anode

2017 ◽  
Vol 5 (40) ◽  
pp. 21536-21541 ◽  
Author(s):  
Chek-Hai Lim ◽  
Baskar Selvaraj ◽  
Yen-Fang Song ◽  
Chun-Chieh Wang ◽  
Jian-Ting Jin ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Transformations ◽  
X Ray ◽  
In Operando ◽  
Delayed Phase ◽  
Insight Into

In operando synchrotron X-ray analyses reveal unique delayed phase transformation and particle fracturing processes of a Bi anode for Na-ion batteries.

Site preference of exchanged alkylammonium ions in heulandite: single-crystal X-ray structure refinements

2000 ◽  
Vol 215 (5) ◽  
Author(s):  
Th. Armbruster ◽  
J. Stolz ◽  
B. Hennessy
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Site Preference ◽  
X Ray

Single crystals (0.1-0.5 mm) of heulandite, Na

Lattice-constant and stress measurement in single crystals: a new method

2005 ◽  
Vol 38 (4) ◽  
pp. 678-684 ◽  
Author(s):  
Balder Ortner
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Lattice Constant ◽  
Stress Measurement ◽  
New Method ◽  
Lattice Plane ◽  
X Ray ◽  
Advantages And Disadvantages

A method for the X-ray determination of lattice-plane distances is given. Similar to Bond's method, it is based on the measurement of rocking curves, with some advantages and disadvantages compared with the former method. The new method is especially designed for single-crystal stress measurement. Its usefulness is demonstrated in two examples of lattice-constant and stress measurement.

scholarly journals Rubidium tetrafluoridobromate(III): redetermination of the crystal structure from single-crystal X-ray diffraction data

IUCrData ◽  
2019 ◽  
Vol 4 (11) ◽  
Author(s):  
Artem V. Malin ◽  
Sergei I. Ivlev ◽  
Roman V. Ostvald ◽  
Florian Kraus
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Diffraction Data ◽  
Structure Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar ◽  
Atomic Coordinates

Single crystals of rubidium tetrafluoridobromate(III), RbBrF4, were grown by melting and recrystallizing RbBrF4 from its melt. This is the first determination of the crystal structure of RbBrF4 using single-crystal X-ray diffraction data. We confirmed that the structure contains square-planar [BrF4]− anions and rubidium cations that are coordinated by F atoms in a square-antiprismatic manner. The compound crystallizes in the KBrF4 structure type. Atomic coordinates and bond lengths and angles were determined with higher precision than in a previous report based on powder X-ray diffraction data [Ivlev et al. (2015). Z. Anorg. Allg. Chem. 641, 2593–2598].

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