The pressure and temperature evolution of the Ca3V2O8 crystal structure using powder X-ray diffraction
We present a comprehensive experimental study of the crystal structure of calcium vanadate (CaVO) under systematic temperature and pressure conditions. The temperature evolution (4-1173 K) of the CaVO structural properties is investigated at ambient pressure. The pressure evolution (0-13.8 GPa) of t...
| Autores: | , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/348797 |
| Acceso en línea: | http://hdl.handle.net/10261/348797 |
| Access Level: | acceso abierto |
| Palabra clave: | Crystal structure Density functional theory Equations of state Rietveld refinement Structural properties Thermal expansion Vanadium compounds |
| Sumario: | We present a comprehensive experimental study of the crystal structure of calcium vanadate (CaVO) under systematic temperature and pressure conditions. The temperature evolution (4-1173 K) of the CaVO structural properties is investigated at ambient pressure. The pressure evolution (0-13.8 GPa) of the CaVO structural properties is investigated at ambient temperature. Across all pressures and temperatures used in the present work, the CaVO crystal structure was determined by Rietveld refinement of powder X-ray diffraction data. The experimental high-pressure data are also supported by density-functional theory calculations. According to the high-pressure results, CaVO undergoes a pressure-induced structural phase transition at a pressure of 9.8(1) GPa from the ambient pressure trigonal structure (space group R3c) to a monoclinic structure (space group Cc). The experimentally determined bulk moduli of the trigonal and monoclinic phases are, respectively, B = 69(2) GPa and 105(12) GPa. The trigonal to monoclinic phase transition appears to be prompted by non-hydrostatic conditions. Whilst the trigonal and monoclincic space groups show a group/subgroup relationship, the discontinuity in the volume per formula unit observed at the transition indicates a first order phase transition. According to the high-temperature results, the trigonal CaVO structure persists over the entire range of studied temperatures. The pressure-volume equation of state, axial compressibilities, Debye temperature (264(2) K), and thermal expansion coefficients are all determined for the trigonal CaVO structure. |
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