Review of ferroelectric materials usable for passive electro-optic alphanumeric display devices

Abstract

Among optical field effect phenomena of known solid state materials, only three are suitable for alphanumeric displays: (i) electric field switching of the spontaneous birefringence, (ii) electric field induced birefringence and (iii) electric field switching of the spontaneous optical rotatory power (electrogyration). The birefringence effects are necessarily coupled with mechanical deformations, whereas electrogyration is not. Among the known ferroelectrics, only a few, Gd₂(MoO₄)3, boracites, Bi₄Ti₃O₁₂, BaTiO3 and PLZT come close to meet the requirements for alphanumeric displays. For large scale production, the development of shear free or very low shear compositions-for single crystals, layers and ceramics-appears mandatory. Possibilities will be discussed. Some PLZT compositions are in an advanced development state.