Anomalous structural phase transition properties in ReSe2 and Au-doped ReSe2

The high pressure induced phase transition in rhenium diselenides (ReSe2) and gold-doped rhenium diselenides (Au-ReSe2) at ambient temperature have been investigated using angular-dispersive x-ray diffraction (ADXRD) under high pressure up to around 10.50 and 9.98 GPa, respectively. In situ ADXRD measurements found that the phase transition pressures of ReSe2 and Au-ReSe2 began at 9.98 and 8.52 GPa, respectively. Compressibilities analysis shows the relationship of along c-axis > along a-axis > along b-axis. The linear compressibility of the pressure dependence of alpha, beta, and gamma of ReSe2 shows that a phase transition can be related to a counterclockwise rotational trend of the selenium atoms around the chain of Re-4 atoms during the decrease of the c-axis distance by a combination of stresses due to the bending effect of alpha and stretching effect of beta. The cause of the reduction of the phase transition pressure of Au-ReSe2 is attributed mainly to a structural distortion as evidenced by the observation of a weak clockwise rotational trend of Se atoms around the chain of Re-4 atoms in the pressure range 3.99-4.99 GPa which subsequently reversed to counterclockwise rotation under higher pressure. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4733985]