A comparative study of LGS coefficient set accuracy assessed by experiments

Recent works have shown the capability of surface acoustic wave (SAW) sensors built on Langasite (LGS) to withstand temperature in excess of 700°C. This emphasizes the need for effective material coefficients allowing for designing SAW resonators with a high level of confidence. The prediction of the device electrical response and more of its temperature coefficient of frequency (TCF) reveals now mandatory. In the proposed paper, the accuracy of the published data sets for LGS and more specifically their capability to predict measured TCF for several crystal cuts supporting Rayleigh and surface transverse waves is assessed. Data from Kaminskii (1983), Ilyaev (1986), Silvestrova (1993), Sakharov (1995) and Bungo (1999) have been used to systematically evaluate their capability to predict first and second order TCF. Considering the experimental data set used to assess the tested coefficients, the authors finally propose a combination of data set allowing for accurate prediction of the device behavior at room and elevated temperature.