Quartz Crystal Applications

Quartz Crystal Applications By W. P. MASON 1.1. INTRODUCTION--PURPOSE OF SERIF . T HIS paper is the first one of a series of papers deai:.2 with quartz crystals, their applications in oscillators, filters, and transducers, and the methods of producing them from the natural crystal. This series was prepared first to make available to the Western Electric Co. and other manufacturers of quartz crystals some of the specialized knowledge on these subjects that has been acquired at the Bell Telephone Laboratories. Sufficient interest has been expressed in this series to make it desirable to publish them in serial form. This first paper in the series is a general introductory paper covering the application of crystals to oscillators, filters and transducers. An appendix is given which discusses the elastic and electric relations in crystals and gives recent measurements of the elastic constants, their temperature coefficients, and the piezoelectric constants of quartz. This paper is followed by more detailed papers by Messrs. Bond, Willard, Sykes, McSkimin, and Fair which give consideration to quartz crystallography; determination of orientation by optical methods, X-ray methods, and etching methods; the imperfections occurring in quartz crystals; modes of motion and their calculation; the dimensioning of crystals to avoid undesirable resonances; and the use of crystals in oscillators. 1.2 EARLY HISTORY OF PIEZOELECTRICITY AND ITS APPLICATIONS The direct piezoelectric effect was discovered by the brothers Curie in 1880.