Raman spectroscopy and lattice-dynamical calculations of Sc sub(3)CrO sub(6) single crystals

Single crystals of Sc sub(3) CrO sub(6) were grown by a high-temperature solution-growth method. They were studied using x-ray single-crystal diffractometry, scanning electron microscopy with x-ray microprobe analysis, and micro-Raman spectroscopy. The crystal structure was refined as a rhombohedral one with space group R3, which confirms that it belongs to the Mg sub(3) TeO sub(6) -structural-type family. In the polarized Raman spectra collected at room temperature all 9A sub(g) + 9E sub(g) Raman-allowed phonon modes were observed. The experimentally determined frequencies are compared to the results of lattice-dynamical calculations using a shell model. The Raman spectra, obtained with increasing temperature up to 600 [degrees]C, do not provide direct indication for structural phase transition. The decrease with increasing temperature of the relative intensity of five A sub(g) lines compared to the rest, however, suggests a possible structural phase transition from R3 to R3c above the investigated temperature region.