Ferrielectrics and Their Application in Solid-State Devices as an Adaptive Control

The basic properties of the recently discovered ferrielectrics, which are essentially degenerate antiferroelectrics exhibiting ferroelectric properties, will be discussed. Capacitors having a ferrielectric dielectric possess a true switching threshold field similar to ferrites. This material opens up a large field of new applications. A new device which operates similar to the transfluxor and represents an electrostatically controlled circuit impedance with stored settings will be discussed. This device called the "transpolarizer" represents one of the most interesting recent achievements in the semiconductor field. Control of polarization transfer through two or more ferroelectric dielectric sections in series represents a new basic means for storing and gating electrical signals and, in general, a means for controlling circuit impedance in any predetermined manner according to a stored setting. The most interesting feature of the transpolarizer is that, by the application of a control signal, it can be changed from a ferroelectric capacitor into a linear capacitor and can assume any intermediate polarization level between these two limits; furthermore, it is capable of controlling a flow of ac electric power according to its setting. Now, for the first time, it is possible to utilize the combination of electrically controlled resistance, inductance and capacitance in circuit design. Switching and storage properties as well as a threshold switching field are simultaneously present in these new devices. Furthermore, the fact that ferrielectric devices are voltage devices makes these devices extremely useful in the fields of pattern recognition, trainable computers and adaptive control.