Comparative study of perovskite-type scintillator materials CsCaI ₃ and KCaI ₃ via first-principles calculations

Several members of a large family of perovskite-like halides with a common chemical formula, ABX 3 (A = monovalent, B = divalent, and X = halogen ion), are being investigated for their interesting properties and potential technological applications. CsCaI 3 and KCaI 3 are two such ionic compounds who are of interest in the quest for superior and cost-effective alternatives to NaI or CsI based scintillators. They are the subject of this first-principles based computational study. Both are wide-gap materials having primarily I 5 p and Ca 3 d characters near the valence and conduction band edges, respectively. Although built from [CaI 6 ] octahedral motifs, structural differences between the two compounds is reflected in anisotropic electron effective mass and distinctive formation and migration of self-trapped holes. We discuss these properties as they relate to scintillation decay and proportional light yield.