Professor Walter G. Cady’s contributions to piezoelectricity and what followed from them

Abstract

In connection with a celebration of Professor Walter G. Cady’s approaching 100th birthday, a resume of some of his most important works on piezo and ferroelectric crystals were discussed. This celebration was held at Wesleyan University in Middletown, Connecticut where he was a professor for over 40 years. Briefly he was the inventor of the crystal‐controlled oscillator, the very selective narrow‐band crystal filter, one of the principal theorists of the ferroelectrical effect in crystals, and the historian par excellence of the science of piezoelectric crystals. These initial efforts have led to many applications, such as (1) crystal filters for separating out the many telephone channels that can be transmitted over radio systems, coaxial systems, and undersea cables; (2) crystal‐controlled oscillators and time standards of use for radio broadcasting, navigation systems, and crystal‐controlled watches; (3) ferroelectric crystals and ceramics which are widely used in such applications as ultrasonic cleane...