New method of change of temperature coefficient delay of acoustic waves in thin piezoelectric plates

As is well known the development of high effective and thermo-stable acoustic devices assumes using the acoustic waves with high coefficient of electromechanical coupling (K-2) and low temperature coefficient of delay (TCD). At present it is also well known that fundamental shear horizontal (SH0) acoustic waves in thin piezoelectric plates possess by significantly more electromechanical coupling compared to surface acoustic waves (SAW) in the same material. However, although the value of TCD of SH0 waves is rather less than for SAW this is not enough for development of thermo-stable devices. This paper suggests a new way of decreasing TCD of SHo waves in piezoelectric plates at high level of electromechanical coupling. This way assumes to use the structure containing the piezoelectric plate and liquid with the special dependence of permittivity on temperature. Theoretical and experimental investigation confirmed the efficiency of such way. It has been shown that SH0 wave propagating in structure "vacuum - YX LiNbO3 plate butyl acetate" at hf = 500 m/s (h = plate thickness, f = wave frequency) is characterized by TCD=10 ppm/C and K-2 =30%. In a whole the obtained results open the wide prospect of using SHo wave in thin piezoelectric plate for development of high effective and thermo - stable acoustic devices.