The vibrational spectrum of a KTiOPO4 single crystal studied by Raman and infrared reflectivity spectroscopy

Potassium titanyl orthophosphate KTiOPO4 has been studied by Raman and infrared reflectivity spectroscopy in the range from a low temperature to room temperature and for various scattering configurations. The absence of a structural phase transition below room temperature is confirmed. The phonon modes are classified within their symmetry species, and their parameters such as damping, oscillator strength and integrated intensity are obtained. On the basis of an internal and external mode analysis and by comparison with related compounds such as RbTiOPO4 and KH2PO4, the origin of the various vibrational groups is discussed. The main part of the scattered intensity is shown to be due to vibrations of the Ti-O bonds.