A computerised method of searching for new ceramic compositions with ferroelectric and piezoelectric properties

A novel method of searching for new ferroelectric and piezoelectric ceramic compositions is described. The approach uses the known crystal structures of existing ferroelectric materials (generating structures) to predict new compositions which are isostructural in detail. Use is made of coordination number-dependent ionic radii, and of the ratios of the volumes of cation coordination polyhedra in the generating structures. Since the occurrence of ferroelectricity has certain crystal structural requirements, it follows that isostructural generated structures are also likely to be ferroelectric. The method is applied to several perovskites, barium titanate, lead titanate, sodium niobate, and to the compound Fe₂Mo₃O₈. Predictions are made of oxide, fluoride and sulphide compositions which are isostructural with these generating structures. The validity of the approach is assessed by comparison with data on some of the predicted compositions, which are in the literature.