温度依存性を考慮した強誘電体の構成モデル

概要

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A simple constitutive model for temperature dependent behavior of ferroelectric materials is developed. To model the temperature dependent behavior of the ferroelectric materials, the paraelectric phase is considered in addition to four types of ferroelectric variants in the ferroelectric phase. These ferroelectric variants are assumed to be connected in series to each other, whereas the paraelectric phase is assumed in parallel to the ferroelectric phase. Volume fraction of the paraelectric phase is to increase with increase in temperature up to the Curie temperature. To verify the validity of the present model, relationships of electric displacement and strain versus electric field were measured at several temperatures and the results from the model were compared with those by the measurement. The comparison reveals that the present constitutive model can well predict the temperature dependent behavior quantitatively. This implies that the present simple model can make it easy to understand the physical mechanism of ferroelectric materials and provides a convenient tool to design smart structures containing the ferroelectric materials over the wide range of temperature.