Piezoresistive properties of ITO strain sensors prepared with controlled nanoporosity
Document Type
Article
Date of Original Version
9-13-2004
Abstract
A ceramic strain gage based on reactively sputtered indium-tinoxide (ITO) thin films is being developed to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500°C. The high-temperature stability and piezoresistive properties depend to a large extent on the thickness of the active ITO strain elements comprising these ceramic strain gages. Scanning electron microscopy of the thick ITO sensors revealed a partially sintered microstructure consisting of a contiguous network of submicrometer ITO particles with well-defined necks and isolated nanoporosity. It appeared that densification of the ITO particles was retarded during high-temperature exposure with nitrogen playing a key role in stabilizing the nanoporosity. Based on. these preliminary results, ITO strain sensors were also prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen-rich grain boundaries was retarded and a contiguous network of nanosized ITO particles was established. The influence of nitrogen in the sputtered and annealed ITO films on the microstructure and the high-temperature piezoresistive properties was investigated, and the results are presented in this paper. © 2004 The Electrochemical Society. All rights reserved.
Publication Title, e.g., Journal
Journal of the Electrochemical Society
Volume
151
Issue
8
Citation/Publisher Attribution
Gregory, Otto J., and Tao You. "Piezoresistive properties of ITO strain sensors prepared with controlled nanoporosity." Journal of the Electrochemical Society 151, 8 (2004). doi: 10.1149/1.1767839.