Netsu Sokutei, 35 (1), p. 2, (2008)



Thermodynamic Properties and Phase Transition of Negative Thermal Expansion Materials

Phonon properties and structural phase transition of negative thermal expansion material, ZrW2O8, were investigated from a thermodynamic point of view. Calorimetric investigation revealed that the phase transition involved the correlated orientational disordering of WO4 units. In the ZrW2O8-based solid solutions, the substitution effects on the phase transition were classified into two types. Spectrum analysis of heat capacity provided the phonon density of states of ZrW2O8 and HfW2O8, showing characteristic features of negative thermal expansion materials.