Predicting and Screening Dielectric Transitions in a Series of Hybrid Organic–Inorganic Double Perovskites via an Extended Tolerance Factor Approach

Extended Goldschmidt tolerance factor t is applied to the hybrid double perovskites (MA)2 B'B''(CN)6 (MA=methylammonium cation) to predict and screen dielectric transitions in 121 compounds through the correlations among t, the radius of the B component rB and the transition temperature Tc , based on experimental results from model compounds. For (MA)2 B'Co(CN)6 , it is concluded that: i) when t>0.873, the cubic phase would be stable below 298 K; ii) when 0.873>t>0.805, the cubic phase would be stable between 298 and 523 K; iii) the larger the rB , the higher the Tc of the perovskite (Tc (1/2) ∝rB ); and iv) the Tc of the hybrid perovskites can be well tuned by doping the B components.