Spectral studies on VO2C ions in potassium thiourea bromide single crystals using EPR and optical absorption spectroscopy

Electron paramagnetic resonance (EPR) studies have been carried out on VO2C ions doped in single crystals of ferroelectric material, potassium thiourea bromide (PTB) at room temperature and in the temperature range 103–343 K on X-band MW frequency. An isotropic octet spectrum characteristic of VO2C ion was obtained due to the fast re-orientation of the VO2C in PTB lattice, which exhibits glassy nature at certain range around room temperature. The temperature dependant EPR spectra of VO2C ions in this host lattice has been attributed to the occurrence of multiple phase transitions due to the combined environment effects of KBr and thiourea materials in the single crystal. From the optical absorption spectrum, the crystal field splitting parameter Dq, tetragonal parameters Ds and Dt have been evaluated and discussed. q 2005 Elsevier B.V. All rights reserved.