Relaxor- and phase-transition-like behaviors in ZnO single crystals at high temperatures

We herein reported the dielectric properties of ZnO single crystals, and three dielectric anomalies were found. The first anomaly shows a relaxor-like behavior. It is composed of two oxygen-vacancy-related relaxation processes: a dipolar relaxation related to the hopping motions of single-ionized oxygen vacancies and a Maxwell-Wagner relaxation as the defects were blocked by the interfaces of sample/electrode contacts. The second anomaly behaves as a phase-transition-like behavior. It is ascribed to the distribution state transition for oxygen vacancies from static disorder to dynamic disorder. The third anomaly exhibits a relaxor-like behavior. It is an artificial effect caused by negative capacitance. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4796136]