Minimal diffraction cuts for acoustic surface wave propagation on Bi12GeO20

Techniques are described for the theoretical prediction of acoustic surface wave orientations on anisotropic crystalline substrates having minimal diffraction spreading. These techniques are illustrated by the theoretical and experimental discovery of a minimal diffraction cut on Bi12GeO20 having diffraction retarded by at least two orders of magnitude over isotropic materials. Euler angles for this orientation are 45°, 40.04°, and 90°, while the surface wave velocity and the Δv/v parameter are 1827 m/sec and 0.0031, respectively.