Quartz crystals for monolithic piezoelectric filters

High-quality quartz crystals on X-cut seeds have been grown by precipitation of crystal-forming substance in the negative direction of the electric axis X. Screens restricting crystal growth in other directions have been used. The Q-factor of the material of the growth zone <-X> was in the range 1.0 /spl times/ 10/sup 6/. The crystals were tested in filter resonators (mainly with two pairs of electrodes) and their suitability for this purpose was established. Another advantage of such quartz was found, namely its high stability with respect to twinning in the case of sharp changes of temperature. This can broaden applications of quartz with a growth zone <-X> and promote the development of ways of glass sealing with high-frequency current.<>