Attenuation of acoustic waves in lithium niobate

The attenuation of acoustic waves in the bulk of LiNbO3 at room temperature has been measured in the frequency range 500 MHz to 10 GHz. The measurement technique involved optical detection at the lower half of the frequency range and high resolution pulse echo method at 9.45 GHz. The attenuation is found to depend on the square of the frequency, so the attenuation coefficient may be given in terms of an effective viscosity value, according to a treatment based on the theory of perturbation. The attenuation coefficient has been determined for various modes and propagation directions allowing the complete determination of the viscosity tensor, from which the attenuation coefficient can be calculated for any desired type of acoustic wave in LiNbO3.