Piezo-electric Oscillations of Quartz Plates at Even and Half-odd Harmonics

IT is well known that a piezo-electric quartz plate can be excited into strong oscillations at its fundamental frequency, mainly determined by its thickness, or at any of its odd multiples, the even multiples being ruled out on theoretical considerations 1 . Parthasarathy 2 first observed that a quartz plate can vibrate at its 5/2 and 7/2 harmonics. Afterwards, Parthasarathy, Pande and Pancholy 3 showed that an X-cut quartz plate could also be made to oscillate, though with a lower intensity, at its even harmonics and such frequencies as ½, 3/2, 5/2, etc., of its fundamentals. This observation was later confirmed by Tsien and Chu 4 and Özdogan 5 . The former also reported that, besides the even and half of odd multiples of the fundamental frequency, the plate would oscillate continuously, though with less intensity, at any intermediate frequency.