Investigation of temperature-dependent phonon dynamics of BixRe1-xSe2 (x=0.0,0.1,0.5) via Raman spectroscopy

The present study focuses on the growth and detailed investigation of temperature-dependent phonon properties of BixRe1-xSe2 (x = 0.0,0.1,0.5) ternary alloys. Here, we have grown BixRe1-xSe2 (x = 0.0,0.1,0.5) ternary alloy crystals by the direct vapour transport (DVT) method and achieved high-quality single crystals. The surface morphological validations of the crystals were determined by HRTEM analysis. The crystallinity of the samples was identified from the SAED pattern. The structural analysis was carried out with aid of powder X-ray diffraction. The shift of the dominant peak towards higher 2 theta shows the substitution of the Bi atom at Re sites. Further Raman spectra of the DVT-grown crystals were recorded in the temperature range of 93 to 333 K. The temperature-dependent Raman spectroscopy of the sample showed a steady redshift and peak broadening of E-g and two A(g) peaks as the temperature varies from 93 to 333 K. Quantitative parameters such as peak position at 0 K (omega(0)) and first-order temperature coefficient (chi) for Raman modes (E-g and two A(g)) are calculated. The results were compared with theoretical models of the three- and four-phonon processes and it was found that the three-phonon process was responsible for the redshift in this case.