Thermal Equations of State for Titanium Obtained by High Pressure—Temperature Diffraction Studies
We have conducted in situ high-pressure diffraction experiments on titanium metal at pressures up to 8.2 GPa and temperatures up to 900 K. From the pressure (P)-volume (V)-temperature (T) measurements, thermoelastic parameters were derived for a titanium based on a modified high-T Birch-Murnaghan equation of state and a thermal pressure approach. With the pressure derivative of the bulk modulus, K0', fixed at 4.0, we obtained: ambient bulk modulus K0=114(3) GPa, temperature derivative of bulk modulus at constant pressure ({partial_derivative}K/{partial_derivative}T)P=-1.1(7)x10-2 GPaK-1 and at constant volume ({partial_derivative}K/{partial_derivative}T)V=-9.0x10-4 GPaK-1, volumetric thermal expansivity aT=a+bT with a=1.2({+-}0.6)x10-5 K-1 and b=2.5({+-}1.1)x10-8 K-2, and the pressure derivative of thermal expansion ({partial_derivative}a/{partial_derivative}P)T=-8.5x10-7 GPa-1K-1. The ambient bulk modulus and volumetric thermal expansion derived from this work are in good agreement with previous experimental results, whereas all other thermoelastic parameters represent the first determinations for the a phase of titanium. For the -phase Ti, we obtained K0=107(3) GPa and volumetric thermal expansivity at 8.1 GPa aT=a+bT with a=6.5({+-}3.5)x10-6 K-1 and b=2.8({+-}0.6)x10-8 K-2. Within the experimental uncertainties, the c/a ratios for a-Ti at both room and high temperatures remain constant over the experimental pressures up to 7.8 GPa, presenting a case against the isotropic force potential used in some theoretical modeling for hcp metals under high pressures.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 960030
- Report Number(s):
- BNL--83016-2009-JA
- Journal Information:
- Physical Review B: Condensed Matter and Materials Physics, Journal Name: Physical Review B: Condensed Matter and Materials Physics Journal Issue: 5 Vol. 78; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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