Ultrasonic microspectroscopy of LiNbO3 and LiTaO3 single crystals for SAW devices

A new ultrasonic microspectroscopy system was developed for accurately and efficiently characterizing material properties under a highly stabilized measurement temperature environment. The system was applied to evaluating elastic homogeneities of commercially available 3-inch-diameter single crystals for surface acoustic wave (SAW) devices: 127.86 degrees YX-LiNbO3, 64 degrees YX-LiNbO3, 36 degrees YX-LiTaO3, and X-112.2 degrees Y LiTaO3. The slight variations in leaky SAW velocity along the pulling axis and the diameter on the water-loaded specimen surfaces were successfully detected. Velocity variations of about 0.01% for LiNbO3 and 0.02% for LiTaO3 were obtained for SAW device substrates. The chemical composition distributions of 0.012 Li2O-mol% for 127.86 degrees YX-LiNbO3 and 0.034 Li2O-mol% for 36 degrees YX-LiTaO3 were evaluated by comparing the measured velocity variations with the sensitivities to chemical composition previously obtained. (C) 2000 Scripta Technica.