Langasite (La3Ga5SiO14) an optical piezoelectric: growth and properties

Langasite (La₃Ga₅SiO₁₄) is a new effective piezoelectric with k≃0.17 and a structure analogous to that of quartz (32 symmetry class). The single crystals with a diameter of about 60 mm and a mass reaching 1 kg were grown by the modified Czochralski method in direction [21¯1¯0](x). The monophase raw material was prepared by the solid phase method. Determined were the main parameters of the crystals´ quality and the functional characteristics of thermostable langasite elements. The basic characteristics of these elements were found to compare favourably with those of quartz. In particular, their resonance interval are 2-3 times as large., the dynamic inductance and dynamic resistance for VAW decrease by 6-18 and 2-6 times respectively, the squared electromechanical coefficient grow by 2-3 times, the losses by SAW propagation drop by 2 times, the dimensions of LGSO elements being smaller by 20-30%