Temperature Dependence of Dielectric Constant with Different Poling Fields in Lead Magnesium Niobate-Lead Titanate Single crystal

概要

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Temperature dependences of poled dielectric constants ε33T/ε0 of [001] 0.70 Pb(Mg1/3Nb2/3)O3-0.30 PbTiO3 (PMN-PT) single crystals with different poling fields were measured to investigate the cause of the fluctuation of the ε33T/ε0. Anomalous ε33T/ε0 > 50,000 at phase-transition temperature between rhombohedral and tetragonal phases (Trt) with a specific poling field (twice coercive field; Ec) were observed in some samples. Those samples also showed higher ε33T/ε0 = 7,700 and piezoelectric constant d33 = 2,000 pC/N at room temperature than those of other samples. Because each sample had the same Curie temperature Tc, the fluctuations are not derived from the variation in crystal composition variation. Easily or not easily polarized crystal parts may exist in the same wafer. And different domain configurations, defects and impurity levels within the wafer may cause the different mobility of polarization. The temperature dependence of ε33T/ε0 measurement is an effective method to investigate the cause of the fluctuation of dielectric and piezoelectric properties of single crystal transducer. Thus, the results of this study provide important guidelines for controlling the fluctuation of these properties of single crystal medical array probes.
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