Influence of a thin layer with arbitrary conductivity on the characteristics of acoustic waves in potassium niobate

The influence of a thin layer of arbitrary conductivity on the characterist ics of acoustic waves in potassium niobate is investigated theoretically. T he conductivity of a thin layer on the surface of a potassium niobate cryst al or plate is shown to have a significant influence on the damping and vel ocity not only of symmetric Lamb waves and quasi-shear-horizontal waves but also of Gulyaev-Bleustein waves. It is found that a relative change in vel ocity as large as 50% can be achieved for quasi-shear-horizontal waves by a ltering the surface conductivity. The results obtained reveal great prospec ts of using potassium niobate to create acoustoelectronic devices with cont rollable characteristics. (C) 1999 American Institute of Physics. [S1063-78 50(99)01904-7].