Electron Transfer Mechanism in PZT Ceramics—Application to Squeeze Ignition

Abstract

The aim of this paper is to clarify the fundamental difference occurring between a soft PZT ceramic and a hard one. The first type presents singly ionised and doubly ionised cation (lead) vacancies and the second one exhibits singly and doubly ionised anion (oxygen) vacancies. In this sense, this work also explains the mechanism that rales piezoelectric igniters and the reason why some materials lead to higher performances. For igniters, two types of systems can be used: the first one corresponds to a slow application of the stress on the piezoelectric element (squeeze) and the second one implies a mechanical shock produced on the element. In the case of “squeeze” igniters, it is clearly evidenced that spark creation only occurs when hard PZTs are used and this effect originates from the crucial role of the effective charge of oxygen vacancies in hard PZTs.

Keywords:

• Doped PZT
• squeeze igniters
• ionic defects
• singly and doubly ionised vacancies
• electron exchange