scholarly journals Crystallographic and optical study of LiNb1 − xTaxO3

2017 ◽  
Vol 73 (3) ◽  
pp. 498-506 ◽  
Author(s):  
S. Huband ◽  
D. S. Keeble ◽  
N. Zhang ◽  
A. M. Glazer ◽  
A. Bartasyte ◽  
...  
Keyword(s):  
Phase Transition ◽  
Lithium Niobate ◽  
Lithium Tantalate ◽  
Flux Growth ◽  
Structural Studies ◽  
Optical Study ◽  
X Ray Diffraction ◽  
Growth Technique ◽  
X Ray ◽  
Li Content

Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points.

scholarly journals Synthesis and structural characterization of Fe1-xMexBO3 (Me = Al, Sc) single crystals

2021 ◽  
Vol 2103 (1) ◽  
pp. 012069
Author(s):  
Yu Mogilenec ◽  
K Seleznyova ◽  
S Yagupov ◽  
K Seleznev ◽  
I Nauhatsky ◽  
...  
Keyword(s):  
Single Crystals ◽  
Fluorescence Analysis ◽  
Flux Growth ◽  
X Ray Diffraction ◽  
Growth Technique ◽  
X Ray ◽  
Synthesis Conditions ◽  
Initial Charge ◽  
Crystal Lattice Parameters

Abstract Fe1-xMexBO3 (Me = Al, Sc) single crystals have been synthesized by flux growth technique using B2O3-PbO-PbF2 solvent and approach of identical synthesis conditions. The contents of the diamagnetic ions Me in the initial charge of both compositions were equal, xcharge=0.05. The exact contents and crystal lattice parameters of the synthesized crystals were determined by X-ray fluorescence analysis and X-ray diffraction, respectively.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

1990 ◽  
Vol 48 (4) ◽  
pp. 172-173
Author(s):  
Naoki Yamamoto ◽  
Makoto Kikuchi ◽  
Tooru Atake ◽  
Akihiro Hamano ◽  
Yasutoshi Saito
Keyword(s):  
Phase Transition ◽  
Electron Microscope Study ◽  
Room Temperature ◽  
Hexagonal Lattice ◽  
Ferroelectric Materials ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Periodic Arrays ◽  
Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

Raman spectroscopy and X-ray diffraction of lithium niobate at temperatures up to 1300○-4.80pt○C

2005 ◽  
Vol 126 ◽  
pp. 101-105 ◽  
Author(s):  
B. Moulin ◽  
L. Hennet ◽  
D. Thiaudière ◽  
P. Melin ◽  
P. Simon
Keyword(s):  
Raman Spectroscopy ◽  
Lithium Niobate ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Struvite Grown in Gel, Its Crystal Structure at 90 K and Thermoanalytical Study

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 89 ◽  
Author(s):  
Jolanta Prywer ◽  
Lesław Sieroń ◽  
Agnieszka Czylkowska
Keyword(s):  
Thermal Analysis ◽  
Sodium Metasilicate ◽  
X Ray Diffraction ◽  
Gel Growth ◽  
Growth Technique ◽  
Thermoanalytical Study ◽  
X Ray ◽  
Cell Parameters ◽  
Thermal Analysis Techniques ◽  
Derivative Thermogravimetry

In this article, we report the crystallization of struvite in sodium metasilicate gel by single diffusion gel growth technique. The obtained crystals have a very rich morphology displaying 18 faces. In this study, the habit and morphology of the obtained struvite crystals are analyzed. The crystals were examined and identified as pure struvite by single X-ray diffraction (XRD). The orthorhombic polar noncentrosymmetric space group Pmn21 was identified. The structure of the crystal was determined at a temperature of 90 K. Our research indicates a lack of polymorphism, resulting from the temperature lowering to 90 K, which has not been previously reported. The determined unit cell parameters are as follows a = 6.9650(2) Å, b = 6.1165(2) Å, c = 11.2056(3) Å. The structure of struvite is presented here with a residual factor R1 = 1.2% at 0.80 Å resolution. We also present thermoanalytical study of struvite using thermal analysis techniques such as thermogravimetry (TG), derivative thermogravimetry (DTG) and differential thermal analysis (DTA).

scholarly journals Pressure-induced Jahn-Teller Switch in the Homoleptic Hybrid Perovskite [(CH3)2NH2]Cu(HCOO)3: Orbital Reordering by Unconventional Degrees of Freedom

2021 ◽  
Author(s):  
Rebecca Scatena ◽  
Michał Andrzejewski ◽  
Roger D Johnson ◽  
Piero Macchi
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Coordination Polymer ◽  
Degrees Of Freedom ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hybrid Perovskite ◽  
Jahn Teller

Through in-situ, high-pressure x-ray diffraction experiments we have shown that the homoleptic perovskite-like coordination polymer [(CH3)2NH2]Cu(HCOO)3 undergoes a pressure-induced orbital reordering phase transition above 5.20 GPa. This transition is distinct...

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