Table of Contents
Smart Materials Research
Volume 2012, Article ID 904168, 9 pages
Research Article

Multilayer Inorganic Electrets with and Layers for Applications on Heated Machinery

Smart Systems and Energy Technology Unit, Imec, Kapeldreef 75, 3001 Leuven, Belgium

Received 29 November 2011; Revised 6 March 2012; Accepted 20 March 2012

Academic Editor: C. R. Bowen

Copyright © 2012 Vladimir Leonov and Chris Van Hoof. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The physics and basic properties of electrets are discussed, namely, what happens during corona charging of dielectrics, why the surface potential and trapped charge show certain limits, where the trapped charge is stored, why and how the charge is released from traps at high temperatures. The experiments have been conducted on single-layer SiO2 and Si3N4 and on multilayer combination of these materials. A strong lateral mobility of charge trapped near the SiO2/Si3N4 interface was observed at elevated temperatures. The positively and negatively charged electrets are compared to each other. The experiments on charge retention at elevated temperatures have shown the studied electrets are suitable for devices working at temperatures of up to 200–300°C.