Equation of State of Tricalcium Phosphate, -Ca3(PO4)2, to Lower Mantle Pressures
The {gamma}-tricalcium phosphate phase ({gamma}-TCP), {gamma}-Ca{sub 3}(PO{sub 4}){sub 2}, is a high-pressure polymorph of tricalcium phosphate with a potential important implication as the reservoir of rare-earth elements and very large lithophile elements in the deep mantle. In situ synchrotron X-ray diffraction measurements of the {gamma}-TCP phase have been carried out using a diamond-anvil cell to 40.29 GPa at room temperature, with a methanol-ethanol mixture as the pressure medium. The pressures in the measurements have been determined by using gold metal as the internal pressure calibrant. The third-order Birch-Murnaghan equation of state fitted to the experimentally defined unit-cell parameters suggests for the {gamma}-TCP phase a density of {rho}{sub 0} = 3.461(1) g/cm{sup 3}, an isothermal bulk modulus of K{sub T} = 100.2(13) GPa, and first pressure derivative of K'{sub T} = 5.48(16). When K'{sub T} is fixed at 4, the derived K{sub T} is 113.1(12) GPa.
- Research Organization:
- Brookhaven National Laboratory (BNL) National Synchrotron Light Source
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 1020033
- Report Number(s):
- BNL--95549-2011-JA
- Journal Information:
- American Mineralogist, Journal Name: American Mineralogist Journal Issue: 10 Vol. 94; ISSN AMMIAY; ISSN 0003-004X
- Country of Publication:
- United States
- Language:
- English
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