Search results for "Rhenium trioxide"
showing 8 items of 8 documents
Disorder-induced Raman scattering in rhenium trioxide (ReO3)
2007
Raman scattering in cubic metallic perovskite (ReO3) was studied at room temperature for well-crystallized monolith, polycrystalline powder and thin film samples. Defect-induced first-order Raman scattering was detected from the sub-surface region, given by the penetration depth of a 633 nm laser, and its origin was explained on the basis of a rigid-ion vibrational model for bulk ReO3. A quenching of the Raman intensity was observed in crystalline monolithic ReO3 upon increasing the temperature up to 250 °C and was related to crystal surface reconstruction/annealing.
Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO3lattice
2016
The influence of hydrogen intercalation on the local structure of rhenium trioxide is studied in-situ by the Re L3-edge EXAFS spectroscopy and analysed using a novel approach, based on the use of evolutionary algorithm and wavelet transform. The proposed method allows us to perform accurate EXAFS analysis within the multiple-scattering approach taking into account contributions from outer coordination shells and to access the information on correlations in atomic thermal motion.
Thermal disorder and correlation effects in anti-perovskite-type copper nitride
2017
This work has been supported by the Latvian National Research Program IMIS2. The EXAFS experiment has been financed from the European Community's Seventh Framework Programme under grant agreement No. 226716 (Project I-20100098 EC). J.T. also gratefully acknowledges support from the National Science Foundation under the DMREF program Grant No. CHE-1534184.
Characterization of rhenium oxide films and their application to liquid crystal cells
2009
Rhenium trioxide exhibits high electronic conductivity, while its open cubic crystal structure allows an appreciable hydrogen intercalation, generating disordered solid phases, with protonic conductivity. Rhenium oxide thin films have been obtained by thermal evaporation of ReO3 powders on different substrates, maintained at different temperatures, and also by reactive magnetron sputtering of a Re metallic target. A comparative investigation has been carried out on these films, by using micro-Raman spectroscopy and x-ray diffraction. Two basic types of solid phases appear to grow in the films: a red metallic HxReO3 compound, with distorted perovskite structures, like in the bulk material, a…
Reverse Monte Carlo modeling of thermal disorder in crystalline materials from EXAFS spectra
2012
Abstract In this work we present the Reverse Monte Carlo (RMC) modeling scheme, designed to probe the local structural and thermal disorder in crystalline materials by fitting the wavelet transform (WT) of the EXAFS signal. Application of the method to the analysis of the Ge K-edge and Re L3-edge EXAFS signals in crystalline germanium and rhenium trioxide, respectively, is presented with special attention to the problem of thermal disorder and related phenomena.
EXAFS study of hydrogen intercalation into ReO 3 using the evolutionary algorithm.
2014
In this study we have investigated the influence of hydrogen intercalation on the local atomic structure of rhenium trioxide using a new approach to EXAFS data analysis, based on the evolutionary algorithm (EA). The proposed EA-EXAFS method is an extension of the conventional reverse Monte Carlo approach but is computationally more efficient. It allows one to perform accurate analysis of EXAFS data from distant coordination shells, taking into account both multiple-scattering and disorder (thermal and static) effects. The power of the EA-EXAFS method is first demonstrated on an example of the model system, pure ReO3, and then it is applied to an in situ study of hydrogen bronze HxReO3 upon …
Understanding the Conversion Process of Magnetron-Deposited Thin Films of Amorphous ReO$_x$ to Crystalline ReO$_3$ upon Thermal Annealing
2020
Crystal growth & design 20(9), 6147 - 6156 (2020). doi:10.1021/acs.cgd.0c00848
FIRST-PRINCIPLES LCAO CALCULATIONS ON 5D TRANSITION METAL OXIDES: ELECTRONIC AND PHONON PROPERTIES
2009
ABSTRACT First-principles quantum chemistry calculations within the periodic linear combination of atomic orbitals (LCAO) formalism have been used to probe electronic and phonon properties of crystalline 5d transition metal oxides ReO3, ZnWO4 and CaWO4. The obtained equilibrium crystal structure is in good agreement with known crystallographic data. Rhenium trioxide is correctly predicted to be a metal, whereas both tungstates—a wide gap insulating compounds. The phonon frequencies, calculated by the frozen phonon method, agree rather well with those obtained by infrared and Raman spectroscopies.