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Comparison of defect processes in REAlO3 perovskites and RE3Al5O12 garnets

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Corresponding author: e-mail ankoor.patel@imperial.ac.uk, Phone: +44 (0)20 7594 6765, Fax: +44 (0)20 7594 6757

Abstract

Defects can decrease the efficiency of scintillators by trapping electrons. Here, point defects in REAlO3 and RE3Al5O12 are predicted with pair potential simulations, where RE is yttrium or a trivalent rare earth cation. It was found that REAlO3 shows a preference for Al2O3-excess whereas RE3Al5O12 most readily exhibits RE2O3-excess. Also, lattice volume changes for the energetically favorable intrinsic mechanisms are relatively invariant as a function of RE cation size in RE3Al5O12, but not in REAlO3. However, in non-stoichiometric RE3Al5O12, the energetically preferred disorder mechanism results in an increasing lattice expansion with increasing RE radius whereas, in non-stoichiometric perovskites, a relatively small, radius independent, lattice contraction is predicted. These results illustrate that defect behavior in REAlO3 perovskites and RE3Al5O12 garnets is quite disimilar.

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