Defect structure of ZrO2-doped rare earth perovskite scintillators

• Published in: Physica Status Solidi (b) 2005-11, Vol.242 (13), p.R113-R115
• Main Authors: Stanek, C. R., Levy, M. R., McClellan, K. J., Uberuaga, B. P., Grimes, R. W.
• Format: Article
• Language: English
• Subjects: 61.72.Bb; 61.72.Ji; 78.60.Kn; 81.05.Je; 87.66.Sq; Charge carriers: generation, recombination, lifetime, and trapping; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Conductivity phenomena in semiconductors and insulators; Electronic transport in condensed matter; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics
• ISSN: 0370-1972; 1521-3951
• DOI: 10.1002/pssb.200541254

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)