The effects of temperature (300-600K) and pressure (0-31.8GPa) on the Raman spectra of natural cinnabar powder were investigated in a heatable diamond anvil cell. Raman spectral changes caused by phase transitions were observed at high pressures, which suggests a phase transformation from pure hexagonal to the coexistence of a hexagonal and rock salt structure, and finally to the rock salt structure. With increasing pressure, A(1) and modes exhibited a blueshift (0.87cm(-1)/GPa) and redshift (-3.64cm(-1)/GPa), respectively, while both modes underwent a redshift (-2.22 and -2.09x10(-2)cm(-1)/K, respectively) with increasing temperature. The mode Gruneisen parameters of A(1) and http://www.w3.org/ at room temperature were calculated by the pressure dependences of the vibrational frequencies and the X-ray diffraction data from previous research. Simultaneous high-pressure and high-temperature results were globally fitted, and the coupling coefficients for temperature and pressure dependence of the Raman shifts were determined to be 7.28x10(-4) and 5.12x10(-4)cm(-1)/KGPa for A(1) and E-TO(2), respectively.

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