A detailed vibrational dynamics study was performed on crystalline YPO4 and ScPO4 using an integrated approach consisting of both Raman scattering spectroscopy and first principles calculations. Single crystals of YPO4 and ScPO4 were grown by the flux method. The crystals, with typical size of about 3x1x1 mm3, have tetragonal xenotime structure showing a good optical quality and are elongated in the c-axis direction. Room-temperature Raman spectra were carried out from single-crystals either in nearly backscattering or 90 degrees geometry under different polarization settings, using in both cases a micro-sampling probe. Raman spectra were excited using different wavelengths (i.e.: 514.5 nm and 568.2 nm) and detected by a CCD (256x1024 pixels) cooled by liquid nitrogen. The scattered radiation was filtered by a triple monochromator (Horiba-Jobin Yvon, model T6400), set in double subtractive/single configuration. Through a proper polarization analysis, all the allowed 12 Raman modes (2A1g, 4B1g, 1B2g and 5Eg) were selected in 90 degree geometry, in turn, and assigned in symmetry. In particular, the external translational mode of B1g symmetry mode was never observed before by means of Raman measurements neither in this compound nor in other rare earth zircon-type orthophosphates was clearly identified by us at about 316 cm1 cm1 in YPO4 single crystals. As for ScPO4 single crystal, two B1g symmetry modes (one external and one internal), both never reported before, were observed by us at about 350 cm1 and about 677 cm1, respectively. The Raman modes of both YPO4 and ScPO4 single crystal have been calculated by density functional theory (DFT) within the generalized gradient approximation. CRYSTAL code package has been used for simulation. The calculated wavenumbers of the 12 Raman active modes were found in good agreement with our experimental data, thus definitively supporting our experimental results.
Vibrational dynamics of YPO4 And ScPO4 single crystals: an integrated study by polarized Raman scattering experiments and simulations.
GIAROLA, Marco;SANSON, Andrea;BETTINELLI, Marco Giovanni;SPEGHINI, Adolfo;MARIOTTO, Gino
2010-01-01
Abstract
A detailed vibrational dynamics study was performed on crystalline YPO4 and ScPO4 using an integrated approach consisting of both Raman scattering spectroscopy and first principles calculations. Single crystals of YPO4 and ScPO4 were grown by the flux method. The crystals, with typical size of about 3x1x1 mm3, have tetragonal xenotime structure showing a good optical quality and are elongated in the c-axis direction. Room-temperature Raman spectra were carried out from single-crystals either in nearly backscattering or 90 degrees geometry under different polarization settings, using in both cases a micro-sampling probe. Raman spectra were excited using different wavelengths (i.e.: 514.5 nm and 568.2 nm) and detected by a CCD (256x1024 pixels) cooled by liquid nitrogen. The scattered radiation was filtered by a triple monochromator (Horiba-Jobin Yvon, model T6400), set in double subtractive/single configuration. Through a proper polarization analysis, all the allowed 12 Raman modes (2A1g, 4B1g, 1B2g and 5Eg) were selected in 90 degree geometry, in turn, and assigned in symmetry. In particular, the external translational mode of B1g symmetry mode was never observed before by means of Raman measurements neither in this compound nor in other rare earth zircon-type orthophosphates was clearly identified by us at about 316 cm1 cm1 in YPO4 single crystals. As for ScPO4 single crystal, two B1g symmetry modes (one external and one internal), both never reported before, were observed by us at about 350 cm1 and about 677 cm1, respectively. The Raman modes of both YPO4 and ScPO4 single crystal have been calculated by density functional theory (DFT) within the generalized gradient approximation. CRYSTAL code package has been used for simulation. The calculated wavenumbers of the 12 Raman active modes were found in good agreement with our experimental data, thus definitively supporting our experimental results.
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