Electromechanical properties of housed piezoelectric CTGS resonators at high temperatures – Modeling of housing influence

Abstract

Abstract The use of piezoelectric sensors in harsh environments requires their protection by housing. Therefore, it is essential to select materials used for the housing carefully. They should not only withstand the same conditions as the active element while providing protection for it, but also influence the piezoelectric component as little as possible. Mechanical stress or electric short-cut of the signals must be avoided as it leads to strong damping and to reduction of e. g. mass or temperature resolution. Therefore, understanding of housing impact on the piezoelectric sensor plays an important role in research and development. Housed as well as unhoused CTGS resonators are analyzed at temperatures up to 1000 °C. The electrical impedance in the vicinity of the resonance frequency is acquired and modeled by electric equivalent circuits that are fitted to the data. The circuit models describing unhoused and housed CTGS resonators are an extension of the Butterworth-van Dyke equivalent circuit. Analysis of the data reveals that the realized housing impacts the behavior of the CTGS resonators only slightly above ca. 600 °C, whereas this influence is negligible for typical applications.