Synthetic quartz crystal and its electrical application

A starting quartz crystal block for oscillators is required to be superior quality and a single crystal but almost all natural quartzs are composed of twins ; the external shapes are irregular; the useful percentage is much lower, leading to much more processing manhour; and further the productive mines of rock quartz for oscillators are mainly located in Brazil. For these reasons, the reseach, development and production of the synthetic quartz crystal without defects are conducted in many countries. This paper described the crystal growth method, properties, quality and the electrical characteristics of the synthetic quartz; explained quartz crystal oscillators and their special features; described mainly the tunning fork oscillators used for the reference oscillation of wristwatches; described AT cut oscillators having stable frequency characteristics over wide temperature range and oscillating high frequency; and indicated other application examples. The present success of the quartz crystal oscillators is based on the mass production of the synthetic quartz crystal of superior quality. (9 figs, 3 tabs, 2 refs)