Possible Phonon Density of States of High-Temperature Phase Structure of the Negative Thermal Expansion Compound ZrW₂O₈

抄録

To study the phonon properties of β-ZrW₂O₈ showing the negative thermal expansion (NTE), the heat capacities of Zr_1−xM_xW₂O_8−y (M = Sc, Lu; x=0.02, 0.04) at low temperatures were measured and analyzed. The analysis presents the effective phonon density of states (DOS) of β-ZrW₂O₈, showing a rounded form around 5 meV. The rounded phonon DOS of β-ZrW₂O₈ is in marked contrast to that of the low-temperature phase of ZrW₂O₈, and their distinction is consistent with the difference in NTE nature between two structures.