Effect of electric twins on acoustic waves in a quartz resonator

Effects of the electric twins in quartz crystal resonators were investigated theoretically and experimentally. In the theoretical study a simple one-dimensional model predicted drastic changes in amplitude distribution, center value of serial resonant frequency (Fs) and its temperature dependence. In the experimental study, electric twins were formed artificially in the usual AT-cut quartz crystal resonators. The twin formation was confirmed by HF etching. Using the X-ray topograph method, we observed vibrating quartz resonators and saw that vibration generated at electrodes propagated into the outside region isotropically, but did not propagate into the region of the electric twin. When we compared Fs values measured before and after forming the twins, we found a clear dependence of Fs shift on the distance between the electrodes and the twins. We also found that twins significantly changed the temperature dependence of Fs. These effects can be useful in new applications.