Scintillation Properties and Electronic Structures of the Intrinsic and Extrinsic Mixed ElpasolitesCs2NaRBr3I3(R=La, Y)

• DOI: 10.1103/physrevapplied.5.024008
• Publication Date: 2016-02-19T18:31:00Z
• Authors: Hua Wei; Mao-Hua Du; Luis Stand; Zhao Zhao; Hongliang Shi; Mariya Zhuravleva; Charles L. Melcher
• Keywords: Condensed Matter - Materials Science; Materials Science (cond-mat.mtrl-sci); FOS: Physical sciences; 02 engineering and technology; 0210 nano-technology; 7. Clean energy; 01 natural sciences; 0104 chemical sciences

Scintillators attract wide research interest for their distinct applications in radiation detection. Elpasolite halides are among the most promising scintillators due to their high structural symmetry and good scintillation performance. Better understanding of their underlying scintillation mechanism opens up new possibilities in scintillator development. In this work, we employ a variety of experimental techniques to study the two mixed-anion elpasolites Cs2NaRBr3I3 (R = La, Y). The emission of intrinsic Cs2NaRBr3I3 with a light yield ranging from 20,000 to 40,000 ph/MeV is dominant by self-trapped exciton emission. Partial substitution of R with Ce introduces a competing emission, the Ce3+ 5d to 4f radiative transition. Ab initio calculations were performed to investigate the electronic structures as well as the binding energies of polarons in Cs2NaRBr6. The calculated large self-trapped exciton binding energies are consistent with the observed high light yield due to self-trapped exciton emission. The unique electronic structure of halide elpasolites as calculated enhances the STE stability and the STE emission. The highly tunable scintillation properties of mixed-anion elpasolites underscore the role of their complex scintillation mechanism. Our study provides guidance for the design of new elpasolites scintillators with exceptional energy resolution and light yield desirable for applications.<br/>12 pages, 14 figures, 60% of the work was presented at 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference. The manuscript is pubilshed on Physical Review Applied<br/>