Lattice Parameters of Calcite in the PT-Plane to 7.62 Kb and 800 K

Abstract

Lattice parameters (a & c) of powdered, polycrystalline calcite in the trigonal-hexagonal system have been determined as a function of pressure and temperature using a hydrothermal diamond anvil cell (DAC), that has been separately described, and a synchrotron x-ray source. Diffraction data was collected using white synchrotron radiation in an energy dispersive technique (EDXRD). Temperature in the resistance heated hydrothermal DAC was measured by thermocouples to a maximum temperature of 800 K, and pressure was measured by the equation of state (EOS) of water, in which powdered calcite was immersed, to a maximum pressure of 7.62 Kb. The resulting study is an attempt to explore the potential of calcite as a double (P & T) internal x-ray standard for high temperature-high pressure (HTHP) crystallographic studies.