Stability of FeVO under Pressure: An X-ray Diffraction and First-Principles Study.

The high-pressure behavior of the crystalline structure FeVO has been studied by means of X-ray diffraction using a diamond-anvil cell and first-principles calculations. The experiments were carried out up to a pressure of 12.3 GPa, until now the highest pressure reached to study an FeVO compound.

Superionic conduction in β-eucryptite: inelastic neutron scattering and computational studies.

β-Eucryptite (LiAlSiO) is known to show super-ionic conductivity above 700 K. We performed inelastic neutron scattering measurements in β-eucryptite over 300-900 K and calculated the phonon spectrum using classical molecular dynamics (MD) simulations. The MD simulations were used to interpret the inelastic neutron spectra at high temperatures.

Phase Transformation, Vibrational and Electronic Properties of KCe(PO): A Combined Experimental and Theoretical Study.

Herein we report the high-temperature crystal chemistry of KCe(PO) as observed from a joint in situ variable-temperature X-ray diffraction (XRD) and Raman spectroscopy as well as ab initio density functional theory (DFT) calculations. These studies revealed that the ambient-temperature monoclinic (P2/n) phase reversibly transforms to a tetragonal (I4/amd) structure at higher temperature. Also, from the experimental and theoretical calculations, a possible existence of an orthorhombic (Imma) structure with almost zero orthorhombicity is predicted which is closely related to tetragonal KCe(PO).

Structural Stability and Anharmonicity of PrTiO: Raman Spectroscopic and XRD Studies.

Herein we report results of pressure- and temperature-dependent Raman scattering studies on PrTiO. Pressure-dependent studies performed up to 23 GPa suggest a reversible phase transition above 15 GPa with subtle changes. Temperature-dependent investigations performed in the range of 77-1073 K showed anomalous temperature dependence of some of the Raman modes.

Structural manipulation and tailoring of dielectric properties in SrTi1-xFexTaxO3 perovskites: Design of new lead free relaxors.

We report composition dependent structure evolution from SrTiO3 to SrFe0.5Ta0.5O3 by powder X-ray and neutron diffraction studies of SrTi1-2xFexTaxO3 (0.

High-Pressure Crystal Structure, Lattice Vibrations, and Band Structure of BiSbO4.

The high-pressure crystal structure, lattice-vibrations, and electronic band structure of BiSbO4 were studied by ab initio simulations. We also performed Raman spectroscopy, infrared spectroscopy, and diffuse-reflectance measurements, as well as synchrotron powder X-ray diffraction. High-pressure X-ray diffraction measurements show that the crystal structure of BiSbO4 remains stable up to at least 70 GPa, unlike other known MTO4-type ternary oxides.

Preparation and crystal structure of K2Ce(PO4)2: a new complex phosphate of Ce(iv) having structure with one-dimensional channels.

In this manuscript we report crystal structure of a new complex binary phosphate K2Ce(4+)(PO4)2 in K2O-P2O5-CeO2 system prepared by solid state reaction at moderate temperature conditions. The prepared material was characterized by powder X-ray diffraction using lab source and synchrotron radiation as well as thermal analyses, Raman scattering, FTIR, and X-ray photoelectron spectroscopic studies. The crystal structure of the compound has been determined from powder XRD data by ab initio structure solution in direct space followed by Rietveld refinements.

Experimental and Theoretical Investigations on Structural and Vibrational Properties of Melilite-Type Sr2ZnGe2O7 at High Pressure and Delineation of a High-Pressure Monoclinic Phase.

We report a combined experimental and theoretical study of melilite-type germanate, Sr2ZnGe2O7, under compression. In situ high-pressure X-ray diffraction and Raman scattering measurements up to 22 GPa were complemented with first-principles theoretical calculations of structural and lattice dynamics properties. Our experiments show that the tetragonal structure of Sr2ZnGe2O7 at ambient conditions transforms reversibly to a monoclinic phase above 12.

Experimental and theoretical investigations on the polymorphism and metastability of BiPO4.

In this work we report the metastability and the energetics of the phase transitions of three different polymorphs of BiPO4, namely trigonal (Phase-I, space group P3(1)21), monoclinic monazite-type (Phase-II, space group P2(1)/n) and SbPO4-type monoclinic (Phase-III, space group P2(1)/m) from ambient and non-ambient temperature powder XRD and neutron diffraction studies as well as ab initio density functional theory (DFT) calculations. The symmetry ambiguity between P2(1) and P2(1)/m of the high temperature polymorph of BiPO4 has been resolved by a neutron diffraction study. The structure and vibrational properties of these polymorphs of the three polymorphs have also been reported in detail.