EPR, ENDOR And Optical Study of Radiation Defects in
Montana State University
Solar, cosmic and nuclear reactor radiations lead to the appearance of defects
in complex oxides. Most of radiation defects are paramagnetic (or can be
recharged to a paramagnetic state). Therefore, magnetic resonance methods,
Electron Paramagnetic Resonance (EPR) and Electron Nuclear Double Resonance
(ENDOR) are one of the most suitable methods for the study of such defects.
The present work reports the EPR/ENDOR and simultaneous EPR/optical study
of defects in single crystals irradiated by visible, UV and gamma photons,
electrons and neutrons. Different oxide materials were investigated. Among
them are lithium and barium borates, potassium titanyl phosphate, barium
titanate, barium-calcium titanate and so on. Isochronal annealing in air
and additional light illumination has been used for the determination of
the stability of radiation defects.
We found that the dominated types of defects formed under visible, UV and
gamma photon irradiation are centers created by lattice defects trapped electron
or hole, recharged impurity ions and recharged regular lattice ions near
intrinsic or extrinsic lattice defects. The dominated types of defects formed
under neutron irradiation are stable Frenkel pairs (interstitial ions and
vacancies) created by the impact mechanism.
Spectroscopic characteristics and models were determined for more than dozen
paramagnetic centers. The obtained characteristics of different interactions
and derived models of radiation defects can be used as cornerstones for theoretical