TY - JOUR
T1 - Pressure-volume-temperature paths in the laser-heated diamond anvil cell
AU - Kavner, Abby
AU - Duffy, Thomas S.
N1 - Copyright:
Copyright 2005 Elsevier Science B.V., Amsterdam. All rights reserved.
PY - 2001/2/1
Y1 - 2001/2/1
N2 - The temperature, pressure, and stress conditions in the diamond anvil cell sample chamber before, during, and after laser heating are mapped by employing standard materials as in situ pressure markers. Unit cell volumes of Pt, MgO, and NaCl were monitored by synchrotron-based x-ray diffraction at temperatures between 300 and 2290 K and pressures ranging from 14 to 53 GPa. To aid in interpreting the resulting pressure-volume-temperature paths, we perform a series of model calculations of the high-temperature, high-pressure x-ray diffraction behavior of platinum subjected to a general stress state. Thermal pressure and thermal expansion effects within the laser-heated volume are observed but are not sufficient to fully explain the measured paths. Large apparent pressure changes can also result from relaxation of deviatoric stresses during heating and partial reintroduction of those stresses during quench. Deviatoric stresses, monitored from both diffraction peak widths and lattice parameter shifts as a function of (hkl), may significantly distort equation of state results if it is assumed that the sample is under hydrostatic pressure. Large-scale, nearly isothermal pressure relaxation events are observed at ∼2000 K. It is proposed that these arise from relaxation of heated components (pressure medium, gasket, cell itself) outside of the directly laser-heated volume.
AB - The temperature, pressure, and stress conditions in the diamond anvil cell sample chamber before, during, and after laser heating are mapped by employing standard materials as in situ pressure markers. Unit cell volumes of Pt, MgO, and NaCl were monitored by synchrotron-based x-ray diffraction at temperatures between 300 and 2290 K and pressures ranging from 14 to 53 GPa. To aid in interpreting the resulting pressure-volume-temperature paths, we perform a series of model calculations of the high-temperature, high-pressure x-ray diffraction behavior of platinum subjected to a general stress state. Thermal pressure and thermal expansion effects within the laser-heated volume are observed but are not sufficient to fully explain the measured paths. Large apparent pressure changes can also result from relaxation of deviatoric stresses during heating and partial reintroduction of those stresses during quench. Deviatoric stresses, monitored from both diffraction peak widths and lattice parameter shifts as a function of (hkl), may significantly distort equation of state results if it is assumed that the sample is under hydrostatic pressure. Large-scale, nearly isothermal pressure relaxation events are observed at ∼2000 K. It is proposed that these arise from relaxation of heated components (pressure medium, gasket, cell itself) outside of the directly laser-heated volume.
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U2 - 10.1063/1.1335827
DO - 10.1063/1.1335827
M3 - Article
AN - SCOPUS:0000703497
VL - 89
SP - 1907
EP - 1914
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 3
ER -