Measured displacement energies of oxygen ions in titanates and zirconates

Optical emission spectra in the 300-700 nm range were collected from four perovskite-structured materials (CaTiO3, SrTiO3, BaTiO3 and CaZrO3), a pyrochlore-structured material (La2Zr2O7) and zirconolite (CaZrTi2O7), using either a Febetron 706 variable energy pulsed-electron-beam generator (pulse duration 3 ns) or a Vickers pulsed-electron LINAC (pulse duration 0.5 mus). The long-lived emissions (up to microseconds after the electron pulse) consist of broad (halfwidths similar to100 nm) bands centred around similar to400 nm. For the CaZrO3, La2Zr2O7 and CaZrTi2O7 samples, the emission intensity per unit dose was also measured as a function of electron beam energy over the range 0.2-0.6 MeV. The data for all three samples suggest a single stage dependence on electron beam energy. CaZrO3, La2Zr2O7, and CaZrTi2O7 have emission thresholds of 0.28 +/- 0.03, 0.27 +/- 0.03, and 0.26 +/- 0.03 MeV respectively, which give oxygen displacement values of 49 +/- 5, 47 +/- 5, and 45 +/- 5 eV respectively. Data collected in this study are discussed in the context of previously measured and calculated oxygen displacement values. Crown Copyright (C) 2003 Published by Elsevier B.V. All rights reserved.