研究目的
Investigating the thermal properties and remnant state variables of ferroelectric ceramics under combined loads of electric ?eld and compressive stress at room temperature.
研究成果
The distributions of thermal properties ?t well into quadratic curves independent of electric and stress ?elds at each of the four temperatures. Remnant state variables also seem to have close correlation among themselves, independent of the levels of applied electric ?eld or stress. The results would be useful in constructing a thermo-electro-mechanical constitutive model for linear and nonlinear behavior of ferroelectric ceramics under both compressive stress and electric ?eld.
研究不足
The study is limited to compressive stresses less than ?50 MPa and electric ?elds less than 0.4 MV m?1 applied at reference temperature 20 °C. The assumption of constant thermal properties in the temperature range between 20 and 110 °C may not hold for all conditions.
1：Experimental Design and Method Selection:
A commercial poled ferroelectric cube specimen is subject to electric ?eld and compressive stress of various magnitudes at the reference temperature 20 °C. After reaching speci?c states of remnant polarization and remnant strains, temperature of the specimen increases under no external load, measuring changes in polarization and strains.
2：Sample Selection and Data Sources:
Ferroelectric cube specimens with 10 mm sides are used, provided by Morgan Technical Ceramics.
3：List of Experimental Equipment and Materials:
Vishay WA-03-062TT-350 strain gauge, Keithley 6514 electrometer, National Instruments PCI 6221 data acquisition board, LABVIEW software, Eurotherm 2408 PID controller.
4：Experimental Procedures and Operational Workflow:
Electric ?eld and compressive stress are applied at reference temperature, then temperature is increased to 110 °C under no external loads, measuring changes in polarization and strains.
5：Data Analysis Methods:
The standard least squares method is used for ?tting data into straight lines to estimate pyroelectric and thermal expansion coe?cients.
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