Defect structure of ZrO₂‐doped rare earth perovskite scintillators

Abstract

The efficiency of scintillator materials is decreased by processes associated with electrons or holes trapped at point defects. It therefore follows that minimizing the concentration of the defects responsible for trapped electrons/holes will in‐ crease the scintillator efficiency. It has been proposed that annealing or doping oxide scintillators with aliovalent ions can change the concentration of point defects (M. Nikl, phys. stat. sol. (a) 178, 595 (2000) [1]). Here, we predict the defect structures corresponding to ZrO2 doping in a series of rare earth aluminate (REAlO3) perovskites. From these calculations, we predict the mechanism leading to the decrease in oxygen vacancy concentration (the predominant electron trap in REAlO3). We propose this mechanism to be an example of “defect engineering”, where a particularly egregious defect is traded for a less deleterious defect. These results can be used to further optimize such scintillator materials. A perfect REAlO3 orthorhombic perovskite unit cell (a), compared to the same unit cell with the defects associated with ZrO2 doping, namely $ {\rm Zr}^\bullet _{\rm RE} $, $ {\rm Zr}^\bullet _{\rm Al} $ and $ {\rm O}'' _{\rm i} $ (b). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Energy nonlinearity in radiation detection materials: Causes and consequences

“…Thermal-quantum effects were also considered in GdAlO 3 [66]. Very recently the effects of doping YAlO 3 and LuAlO 3 with Zr were predicted [67] through atomistic simulations, and the trends in activator atom gap levels were elucidated [68]. However, no explicit connection between all these issues and nonlinearity has yet been made.…”

Crystal growth and scintillating properties of (Pr,Si)‐doped YAlO3

“…predicted that an excessive charge introduced by Zr ions in YAP:Ce can reduce the concentration of oxygen vacancies [8]. Si-codoping is expected to have similar with Zr positive influence on reducing the oxygen vacancies.…”

Oxygen transport mechanisms in REAlO3 scintillators

“…In a previous paper, we predicted the mechanism by which the oxygen vacancy is minimized through ZrO 2 doping, namely by producing oxygen interstitials that are able to recombine with existing oxygen vacancies [9]. Moreover, Zr dopant ions were predicted to reside on both RE and Al sites, suggesting that these Zr defects are less deleterious to scintillator performance than oxygen vacancies.…”