Using resonant-ultrasound spectroscopy, we measured alpha-plutonium's bulk modulus B between 298 and 18 K. Fitting the measurements to an Einstein-oscillator-based function gave the zero-temperature bulk modulus Bo =70.9 GPa. We compare our measurement with numerous previous measurements and with numerous theoretical estimates ranging from 41 to 227 GPa. From 0 to 300 K, B (T) is regular and smooth, evincing no phase transition (electronic, magnetic, structural). The bulk modulus decreases to 54.4 GPa, about 30%, a very large change compared with typical materials. We attribute this large decrease to electron localization during warming. High-temperature dBdT yields a Gruneisen parameter γ=5.1, too high we believe because of temperature-induced electron localization. From the low-temperature elastic constants, averaged in the usual Debye v-3 manner, we obtain a Debye temperature ΘD =205 K.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 2005|