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

Abstract

  Temperature dependences of poled dielectric constants ε₃₃^T/ε₀ of [001] 0.70 Pb(Mg_1/3Nb_2/3)O₃-0.30 PbTiO₃ (PMN-PT) single crystals with different poling fields were measured to investigate the cause of the fluctuation of the ε₃₃^T/ε₀. Anomalous ε₃₃^T/ε₀ > 50,000 at phase-transition temperature between rhombohedral and tetragonal phases (Trt) with a specific poling field (twice coercive field; E_c) were observed in some samples. Those samples also showed higher ε₃₃^T/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 T_c, 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 ε₃₃^T/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.