Ferroelectricity in organic-inorganic double halides

A classification of organic-inorganic double halides based on the dimensionality of the corner sharing of anion polyhedra is proposed. Ferroelectricity, resp. antiferroelectricity can occur in all structural types. The main object of present research is the [(CH3)4N]2MX4 family because of the occurence of incommensurate structures and different phase sequences making the study of solid solutions an interesting object of future research. An evaluation of possible applications needs a deeper study of relevant material constants.