Principles of melting in hybrid organic–inorganic perovskite and polymorphic ABX(3) structures

Four novel dicyanamide-containing hybrid organic–inorganic ABX(3) structures are reported, and the thermal behaviour of a series of nine perovskite and non-perovskite [AB(N(CN)(2))(3)] (A = (C(3)H(7))(4)N, (C(4)H(9))(4)N, (C(5)H(11))(4)N; B = Co, Fe, Mn) is analyzed. Structure–property relationships are investigated by varying both A-site organic and B-site transition metal cations. In particular, increasing the size of the A-site cation from (C(3)H(7))(4)N → (C(4)H(9))(4)N → (C(5)H(11))(4)N was observed to result in a decrease in T(m) through an increase in ΔS(f). Consistent trends in T(m) with metal replacement are observed with each A-site cation, with Co < Fe < Mn. The majority of the melts formed were found to recrystallise partially upon cooling, though glasses could be formed through a small degree of organic linker decomposition. Total scattering methods are used to provide a greater understanding of the melting mechanism.