Typical characteristics of a piezoelectric ceramic material for squeeze igniters

A squeeze igniter is a mechanical-electrical reversible piezoelectric transducer working under a slow quasi isothermal stress and generating numerous sparks. The mechanism of the energy conversion under a constant stress in a spark igniter is analysed from the linear diagram strain-stress S₃ (T₃) of a piezoceramic. To withstand the highest-stresses reversibly applied without depolarizing the sample, PZT type materials with suitable substitutions and oxygen vacancies are chosen. In order to improve the number of sparks and the energy of each spark the materials must offer both high g ₃₃ and ε₃₃^T coefficients and a high static leakage resistance in the operating stresses range. These conditions are achieved for the best with the help of slightly hard PZT solid solutions doped with undervalenced ions on the Pb site and lying on the rhombohedral side of the MPB