A study of the BaTiO3: CeO2 crystal structure by EPR

Abstract

The crystal structuroef BaTi03:Ce02 was studied using theE PR spectrum of Fe3- ions, contaminating pure BaTiO3, in the temperature range -160C to +l60C. The observed powder spectra are classifiedinto three parts: pure, lightly doped(0.05-0.5 moles% Ce02), and heavily doped (1-3 mole% CeO2) BaTiO3. The EPR spectrum of pure BaTiO3 showed five resonance lines, at room temperature. around g = 2. On lowering the temperature, thef ive lines tend to converge towards the central line. The lightly doped EPR spectra reflected that the crystal fields experienced by Fe3+ ions are highly in homogeneous and g-values in all the range g = 12 to g = 1.8 may be observed. The heavily doped samples reflected an obvious stabilisation of crystal structure with variation of temperature. The g-value reflected the effect of the dopant concentration and showed little or no variation with temperature. All observations confirm the possibility of observing crystallographic phase changes in ferroelectric polycrystalline BaTiO3 with different CeO2 concentrations by observing the EPR spectra of high spin (Fe3-) ions in polycrystalline BaTiO3 at various temperatures.