Cation Ordering in Brownmillerite-Perovskite Intergrowth Structures

1992 ◽  
Vol 293 ◽  
Author(s):  
Julie K. Thomas ◽  
Wendy E. Krause ◽  
Hans-Conrad Zur Loye
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
Cation Ordering ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Ion Conductivity ◽  
Oxygen Ion ◽  
Cubic Structure ◽  
Intergrowth Structures ◽  
Cation Arrangement

AbstractBrownmillerite-perovskite intergrowths of the type m(A2B2O5)*n(ABO3), where m = 1 and n = 1, were investigated with respect to cation ordering. It was found that Sr31n2ZrO8, Sr31n2HfO8, Ba3Sc2TiO8 and Ba31n2TiO8 form in a disordered cubic structure, while Sr3Sc2ZrO8 and Ba3Sc2ZrO8 form an ordered cation arrangement. The Arrhenius plots of the oxygen ion conductivity of Ba3Sc2ZrO8, Sr31n2HfO8, and Ba31n2TiO8 contain discontinuities that appear to be caused by an oxygen vacancy order-disorder transition. High temperature powder-X ray diffraction did not show any evidence for cation ordering that might otherwise have created the changes in activation energy in the conductivity plots.

X-ray investigations into silica/silver nanocomposite

2017 ◽  
Vol 32 (S1) ◽  
pp. S82-S86 ◽  
Author(s):  
K. Dudek ◽  
J. Podwórny ◽  
M. Dulski ◽  
A. Nowak ◽  
J. Peszke
Keyword(s):  
High Temperature ◽  
Diffraction Data ◽  
High Stability ◽  
Amorphous Matrix ◽  
Silver Ions ◽  
Synthesis Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silver Nanocomposite ◽  
Cubic Structure

X-ray diffraction data revealed that the initial SiO2/Ag nanocomposite, manufactured in a chemical synthesis process, is mainly composed of silica in amorphous phase (95.5 wt.%), crystalline Ag with a cubic structure (Fm-3m) and cristobalite (SiO2) with a tetragonal structure (P41212) in the amount of 4.2 and 0.3 wt.%, respectively. High-temperature diffraction data revealed high stability of the SiO2/Ag composite up to 1000 °C. High-temperature X-ray diffraction measurements revealed phase cristallization temperatures of silica at 1060 °C for cristobalite and 1080 °C for tridymite as well as temperature of silver evaporation starting from the composite (ca. 1000 °C). Infrared spectroscopy data confirmed the presence of amorphous matrix with embedded silver ions and crystalline compounds in the form of cristobalite and tridymite without silver after thermal treatment.

Differential Scanning Calorimetry and Guinier Camera/High-Temperature X-Ray Diffraction Studies of the Oxygen Sublattice Phase Transition in the Yba2Cu3O7−x System

1987 ◽  
Vol 99 ◽  
Author(s):  
David S. Lee ◽  
Zezhong Fu ◽  
Egon Hellstern ◽  
William L. Johnson ◽  
Paul Pietrokowsky ◽  
...  
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
High Temperature ◽  
Chemical Potential ◽  
X Ray Diffraction ◽  
Oxygen Sublattice ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrd Techniques

ABSTRACTWe have studied the phase transition of the oxygen sublattice in the YBa2Cu3O7−x system by Differential Scanning Calorimetry (DSC), Guinier Camera, and high temperature x-ray diffraction (ht-xrd) techniques. The transition was examined under different thermodynamic constraints (constant oxygen partial pressure and constant oxygen concentration) and for a range of oxygen partial pressures. The variation of the endothermic peak temperature with DSC scanning rate was used to deduce an activation energy for the transition. The average activation energy for the process is between 38.7–75.0 kcal/mole(l:2:3) [mole], depending on the thermodynamic constraint imposed on the system.Pressure versus concentration isotherms (P(C)) were used to determine the chemical potential of the oxygen in this system.

High temperature X-ray diffraction investigation of an aluminium-silicon-corundum system

2007 ◽  
Vol 2007 (suppl_26) ◽  
pp. 369-374 ◽  
Author(s):  
D. Garipoli ◽  
P. Bergese ◽  
E. Bontempi ◽  
M. Minicucci ◽  
A. Di Cicco ◽  
...  
Keyword(s):  
High Temperature ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals High-pressure synthesis and crystal structure of the mixed-cation borate Ga4In4B15O33(OH)3

2019 ◽  
Vol 74 (4) ◽  
pp. 357-363
Author(s):  
Daniela Vitzthum ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
Mixed Cation ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe mixed cation triel borate Ga4In4B15O33(OH)3 was synthesized in a Walker-type multianvil apparatus at high-pressure/high-temperature conditions of 12.5 GPa and 1300°C. Although the product could not be reproduced in further experiments, its crystal structure could be reliably determined via single-crystal X-ray diffraction data. Ga4In4B15O33(OH)3 crystallizes in the tetragonal space group I41/a (origin choice 2) with the lattice parameters a = 11.382(2), c = 15.244(2) Å, and V = 1974.9(4) Å3. The structure of the quaternary triel borate consists of a complex network of BO4 tetrahedra, edge-sharing InO6 octahedra in dinuclear units, and very dense edge-sharing GaO6 octahedra in tetranuclear units.

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals Structural and Enhanced Optical Properties of Stabilized γ‒Bi2O3 Nanoparticles: Effect of Oxygen Ion Vacancies

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1023 ◽  
Author(s):  
Ashish Chhaganlal Gandhi ◽  
Chia-Liang Cheng ◽  
Sheng Yun Wu
Keyword(s):  
Room Temperature ◽  
Excess Oxygen ◽  
Ambient Atmosphere ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Band Emission ◽  
Oxygen Ion ◽  
Integrated Intensity ◽  
Effect Of Oxygen

We report the synthesis of room temperature (RT) stabilized γ–Bi2O3 nanoparticles (NPs) at the expense of metallic Bi NPs through annealing in an ambient atmosphere. RT stability of the metastable γ–Bi2O3 NPs is confirmed using synchrotron radiation powder X-ray diffraction and Raman spectroscopy. γ–Bi2O3 NPs exhibited a strong red-band emission peaking at ~701 nm, covering 81% integrated intensity of photoluminescence spectra. Our findings suggest that the RT stabilization and enhanced red-band emission of γ‒Bi2O3 is mediated by excess oxygen ion vacancies generated at the octahedral O(2) sites during the annealing process.

Mechanical Alloying Behavior in the Nb-Si, Ta-Si, and Nb-Ta-Si Systems

1988 ◽  
Vol 133 ◽  
Author(s):  
K. S. Kumar ◽  
S. K. Mannan
Keyword(s):  
High Temperature ◽  
Mechanical Alloying ◽  
Mechanical Milling ◽  
Room Temperature ◽  
Crystalline Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

ABSTRACTThe mechanical alloying behavior of elemental powders in the Nb-Si, Ta-Si, and Nb-Ta-Si systems was examined via X-ray diffraction. The line compounds NbSi2 and TaSi2 form as crystalline compounds rather than amorphous products, but Nb5Si3 and Ta5Si3, although chemically analogous, respond very differently to mechanical milling. The Ta5Si3 composition goes directly from elemental powders to an amorphous product, whereas Nb5Si3 forms as a crystalline compound. The Nb5Si3 compound consists of both the tetragonal room-temperature α phase (c/a = 1.8) and the tetragonal high-temperature β phase (c/a = 0.5). Substituting increasing amounts of Ta for Nb in Nb5Si3 initially stabilizes the α-Nb5Si3 structure preferentially, and subsequently inhibits the formation of a crystalline compound.

Sign in / Sign up

Export Citation Format

Share Document