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 Δ S _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.
Competing Interests: There are no conflicts to declare.
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