Observation of two kinds of phase transitions of ZrW2O8 by power-compensated differential scanning calorimetry and high-temperature X-ray diffraction
Autor: | T Katsube, Takuya Hashimoto, Y Morito |
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Rok vydání: | 2000 |
Předmět: | |
Zdroj: | Solid State Communications. 116:129-132 |
ISSN: | 0038-1098 |
DOI: | 10.1016/s0038-1098(00)00302-1 |
Popis: | Two kinds of phase transitions were observed for ZrW2O8 at 123 and 164°C with power-compensated differential scanning calorimetry. An endothermic peak was observed at 123°C in the DSC curve, indicating that the phase transition at this temperature is of the first order. The variation of enthalpy, ΔH, at the phase transition was estimated to be ∼290 J/mol. The base-line shift of the DSC curve, corresponding to the second-order phase transition, was observed at 164°C. The change in the heat capacity, ΔCp, at 164°C was calculated to be ∼20 J/(mol K), showing good agreement with the result of adiabatic calorimetry. The X-ray diffraction patterns of ZrW2O8 below 120°C and above 164°C could be explained by using models with space groups of P213 (No. 198) and Pa 3 (No. 205), respectively. Changes of the linear thermal expansion coefficients were observed at around 123 and 164°C, showing good agreement with the phase transition temperatures measured with DSC. |
Databáze: | OpenAIRE |
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