Research on the Fabrication of BaTiO3-Based PTCR Materials and Thermistors by Polyacrylamide Gel Process
BaTiO3-based powders used for positive temperature coefficient of resistance (PTCR) were synthesized by polyacrylamide gel process. The effect of synthesis conditions such as the pH of the citrate solutions and the reticulation of the polyacrylamide gel on the objection phase was investigated. The results showed that when the citrate solutions had a neutrality pH of 7~8 and the polyacrylamide gel was hard reticulated, precursor powder with pure and completely crystallized objection phase was obtained at calcination temperature of more than 700°C. The results of XRD and TEM revealed that precursor powder had an average grain size of about 50 nm. Compared with those prepared by solid-state reaction, PTCR ceramics prepared by polyacrylamide gel process have one magnitude higher ratio of maximum to minimum of resistance and low sintering temperature, which provides a practical and theoretical foundation for preparing multilayer PTCR thermistors by co-firing of semiconducting BaTiO3 ceramics and electrode.
Z. P. Zheng et al., "Research on the Fabrication of BaTiO3-Based PTCR Materials and Thermistors by Polyacrylamide Gel Process", Advances in Science and Technology, Vol. 45, pp. 2371-2375, 2006