Anomalous behaviour of thermodynamic properties at successive phase transitions in (NH 4 ) 3 GeF 7
| Autor: | Evgeniy V. Bogdanov, E. I. Pogorel’tsev, Igor N. Flerov, Andrey V. Kartashev, Natalia M. Laptash, Mikhail V. Gorev |
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| Rok vydání: | 2017 |
| Předmět: |
Phase transition
010405 organic chemistry Chemistry Hydrostatic pressure Thermodynamics Dielectric 010402 general chemistry Condensed Matter Physics Thermodynamic equations 01 natural sciences Heat capacity Thermal expansion 0104 chemical sciences Electronic Optical and Magnetic Materials Inorganic Chemistry Thermal Materials Chemistry Ceramics and Composites Physical and Theoretical Chemistry Entropy (order and disorder) |
| Zdroj: | Journal of Solid State Chemistry. 256:162-167 |
| ISSN: | 0022-4596 |
| Popis: | Heat capacity, thermal dilatation, susceptibility to hydrostatic pressure and dielectric properties associated with succession of three phase transitions below room temperature in double fluoride salt (NH 4 ) 3 GeF 7 were studied. A possible transformation into the parent Pm -3 m cubic phase was not observed up to the decomposition of compound. Nonferroelectric nature of structural distortions was confirmed. The DTA under pressure studies revealed a high temperature stability of two phases: P 4 /mbm and Pbam . The entropies of the phase transitions agree well with the model of structural distortions. Analysis of the thermal properties associated with the individual phase transitions in the framework of thermodynamic equations has shown a high reliability of the data obtained. |
| Databáze: | OpenAIRE |
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