Thermoelastic equation of state of molybdenum
We report some high P-T diffraction experimental results on molybdenum using synchrotron x-ray and time-of-flight neutron-diffraction techniques. Unit-cell dimensions, measured up to P=10GPa and T=1475K, were derived from the refinement results and fitted to a high-temperature third-order Birch-Murnaghan equation of state. The derived thermoelastic parameters for molybdenum are: isothermal bulk modulus K{sub T0}=266(9)GPa with a pressure derivative of bulk modulus {partial_derivative}K/{partial_derivative}P=4.1(9), temperature derivative of bulk modulus {partial_derivative}K/{partial_derivative}T=-3.4(9)x10{sup -2}GPa/K, volumetric thermal expansivity {alpha}=a+bT having a=1.32(14)x10{sup -5}K{sup -1} and b=1.26(15)x10{sup -8}K{sup -2}. Further, all of the previous experimental data involving shock wave, ultrasonic, thermal-expansion measurements were also analyzed and fitted to a high-temperature Birch/Vinet equation of state (EOS) and the thermal pressure approach of Mie-Gru''neisen EOS, respectively. With the greatly extended P-V-T data coverage, we refined the thermoelastic parameter set for molybdenum as isothermal bulk modulus K{sub T0}=268(1)GPa with pressure derivatives of bulk modulus {partial_derivative}K/{partial_derivative}P=3.81(6), {partial_derivative}K{sup 2}/{partial_derivative}P{sup 2}=-1.41(13)x10{sup -2}, temperature derivative of bulk modulus {partial_derivative}K/{partial_derivative}T=-2.13(31)x10{sup -2}GPa/K, volumetric thermal expansivity {alpha}=a+bT having a=1.31(10)x10{sup -5}K{sup -1} and b=1.12(11)x10{sup -8}K{sup -2}, and an invariant of {alpha}K{sub T}=5.43(5)x10{sup -3}GPa/K over a wide P-T range. We have conducted a neutron-diffraction study at simultaneous high pressures and high temperatures. Thermal vibrations of atoms (Debye-Waller factors) of molybdenum were derived as a function of pressure and temperature. The experimental results of thermoelastic equation of state parameters are compared with previous experimental data derived from shock wave and ultrasonic elasticity measurements.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40205604
- Journal Information:
- Physical Review B, Vol. 62, Issue 13; Other Information: DOI: 10.1103/PhysRevB.62.8766; Othernumber: PRBMDO000062000013008766000001; 016037PRB; PBD: 1 Oct 2000; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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