On Bleustein-Gulyaev waves in thermo-piezoelectricity and in thermo-piezoelectromagnetism

In 1968-69 Bleustein and Gulyaev discovered a new type of piezoelectric surface waves, for any material in class C6v(6mm), having no counterpart in a purely elastic homogeneous material of the same elastic symmetry as the piezoelectric material. This discovery generated an extensive literature on the subject, with extensions to piezoelectromagnetism too. Here we study generalizations of this type of surface waves in the presence of thermal fields for thermopiezoelectric mate- rials with hexagonal symmetry. The exact solutions are written for a class of stationary waves varying harmonically with time, which couple both modes of propagation.