In addition to specific electromechanical coupling factor and mechanical quality factor, good stability of piezoelectric property is also an important requirement for piezoelectric ceramics used in resonators and filters. Because resonant frequency decides piezoelectric properties and central frequency of filters, temperature coefficient of resonant frequency($TCf_r$) is especially important.
In the $Pb(Zr,Ti)O_3$ system, $TCf_r$ has been investigated by ways of changes in composition, phase, and fabrication process. In this study, all specimens were manufactured under the same conditions to exclude effects of composition, phase, and fabriation process changes and their $TCf_rs$ were measured with various heat treatment after poling.
The temperature characteristics of resonant frequency were investigated while conditions(time, temperature, and heating cycles, etc.) of heat treatment after poling were changed. As time, temperature, and number of heating cycles were increased, temperature coefficient of resonant frequency was shifted to negative direction. From this result, The temperature characteristics of resonant frequency($TCf_r$) was understood as the function of domain reorientation by increasing temperature.
