Structure-composition-property relationships in complex ACu3B4O12 perovskites

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Preliminary results in our laboratory have shown two members (CaCu3Ti4O12, CCTO, and Na1/2Bi1/2Cu3Ti4O12) from a large family of perovskite-related compounds based on the general formula ACu3B4O12 have high intrinsic permittivity (> 100) at low temperatures and that appropriate doping (with Mn) can produce ceramics with encouraging microwave dielectric resonance properties at room temperature. The large values of intrinsic permittivity suggests some (as yet unknown) form of additional polarisation, other than ionic polarisation plays an important role in these compounds and that ACu3Ti4O12-type materials possess fundamentally interesting dielectric behaviour and potentially useful bulk dielectric properties after appropriate chemical doping. The aim of this study is therefore to prepare and characterise a wide variety of undoped and Mn-doped ACu3B4O12-type compounds to establish their structure-composition-property relationships. Particular emphasis will be given to optimising the bulk dielectric properties to assess their potential as commercially-useful high permittivity and/or temperature-stable dielectrics.