Acoustic loss phenomena in alpha quartz-crystal resonators over the 1.4–77 K temperature range

Abstract

The acoustic loss phenomena of conventional and electrodeless quartz-crystal resonators over the temperature range from 1.4 to 77 K were investigated. The AT electrodeless resonator of the BVA type exhibited smaller acoustic losses than the conventional FC crystals at the ionic sodium impurity relaxation temperature (∼50 K) and acoustic wave interaction with thermal phonon temperature (∼20 K). A dramatic decrease in the acoustic losses in the electrodeless resonator was observed at temperatures in the range from 1.4 to 5 K. This decrease is attributed to a decrease in two-level energy excitations in this type of resonator. Furthermore, acoustic attenuation was shown to be a function of microwave power absorbed by the crystal plates.