Intervalence charge transfer in perovskite titanates R1/2Na1/2TiO3:Pr3+ (R=La, Gd, Y, Lu)

The spectroscopic properties of R1/2Na1/2TiO3:Pr3+ (R=La, Gd, Y, Lu) are investigated in the temperature range 77-500 K and interpreted in the frame of the intervalence charge transfer (IVCT) model. The model allowed locating the ground state of Pr3+ relative to the host fundamental bands with an accuracy of 0.1-0.2 eV.