Properties, production and application of new piezoelectric crystal lithium tetraborate Li2B4O7

The piezoelectric, elastic, dielectric, thermal, optical, mechanical, chemical, surface acoustic wave (SAW) and bulk acoustic wave (BAW) coupling, and propagation properties of new piezoelectric-crystal lithium tetraborate Li₂B₄O₇ (LBO) are reviewed. The growth and production of LBO crystal by the modified Bridgman (BR) technique (Fan´s process) and its application to SAW and BAW devices are also discussed. Attention is also given to such features of LBO growth as the critical requirement of stoichiometric purity for raw material, very low crystal growth rate, a convex or plane solid-liquid interface in the growth, a suitable procedure of self-annealing, and the practicality of the BR technique for commercialization of LBO material with a large diameter of 82 mm and high quality