GB853193A - Improvements in or relating to ferroelectric data storage devices - Google Patents

Abstract

853,193. Circuits employing bi-stable ferroelectric elements. GENERAL ELECTRIC CO. Ltd. July 11, 1958 [April 17, 1957], No. 12528/57. Class 40 (9). [Also in Group XXXVI] A ferro-electric data storage device comprises a plate of ferro-electric material, coated on one side with a material having a non-linear impedance characteristic, between two electrodes. The preferred form of the invention is as an array of data storage elements, as shown in Fig. 3, where 1 is a plate of ferro-electric material 1 cm. square and 0.01 cm. thick, 3 is the non- linear impedance material, and 200 to 249 and 400 to 449 the electrodes, one data storage element being formed at each intersection of an electrode of the series 200 to 249 with an electrode of the series 400 to 449. The ferro-electric material may be barium titanate, preferably a slice from a single crystal. The " non-linear impedance " material being, e.g., cadmium sulphide activated with gallium settled on the face of the element from a solution of benzene or amyl acetate containing ethyl cellulose as a binder or dusted on to the surface after the surface has been wetted with a suitable binder. Alternatively the layer may be of a powdered semi-conductor, e.g. silicon carbide, in a binder. The electrodes are preferably of gold evaporated on to the surface through a suitable mask. The ferro-electric plate may be coated on both sides with the non-linear impedance material and additional electrodes may be placed between the ferro-electric plate and the non-linear impedance material. The addition of the non- linear impedance material is said to increase the ratio of the value of the voltage pulse that will just not change the state of polarization of the dielectric to that value that just will.