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
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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