Determination Method of Acoustical Physical Constants and Their Temperature Coefficients of La_3Ta_(0.5)Ga_(5.3)Al_(0.2)O_(14) Single Crystal

摘要

We proposed a determination method of accurate acoustical physical constants and their temperature coefficients for La_3Ta_(0.5)Ga_(5.3)Al_(0.2)O_(14) (LTGA) single crystal using the ultrasonic microspectroscopy (UMS) technology combined with the resonance method. Acoustic properties were measured at 20， 23, and 26℃ by the UMS system for X-,Y-, Z-, 29.14°Y-, and 150.86°Y-cut specimens prepared from an LTGA ingot. Using the measured results (longitudinal- and shear-wave velocities, dielectric constants, density, and thermal expansion coefficients), we determined acoustical physical constants and their temperature coefficients around room temperatures. To confirm the accuracy of the determined constants, we compared the measured LSAW velocities and calculated ones using the determined constants at 23℃, resulting in good agreement within -3.0 to 1.1 m/s for all propagation directions. Using four X-cut rotated Y-bar (-30°Y,-15°Y, 0°Y, +30°Y) specimens and Y-cut specimen prepared from the same ingot, we also obtained the temperature coefficients in a range from -30 to +80℃ by the resonance method. Combining the temperature coefficients obtained by the resonance method with the absolute values of constants obtained by the UMS technology, we can determine more reliable constants and temperature coefficients.