Papers by Author: Wei Qiang Wang

Abstract: Various deposits of CdO grains were observed on the surface of N 100 silicon crystals heated at 580 °C and 620 °C for 1 hour in an evaporation-deposition device, respectively. The ball-shaped crystals, and regular-prism-shaped crystals were found on top of bush-like long crystals. Two types of CdO self-organization aggregates were also observed, that is, regular circular-shaped dense aggregate and long-chainshaped aggregate. The self-organization aggregates were composed of numerous submicron CdO grains. The relationship between self-organization aggregates and surface defects of virgin N 100 silicon crystal was investigated. The results showed that the CdO self-organization aggregates were related to surface defects of the virgin N 100 silicon crystal, and a defect induced aggregation (DIA) model is suggested.

Abstract: Electric fatigue of piezoelectric ceramics is very important for piezoelectric actuator applications in strong field. In order to classify the fatigue of ferroelectric and piezoelectric properties, the electric fatigue behavior of piezoelectric ceramics of PZT-PMN-PNN was investigated under bias and unipolar pulse cycling field. The bias and unipolar polarization hysteresis loops are measured before and after cycling. The polarization measurements after cycling show a much smaller decrease than bipolar fatigue, but the piezoelectric coefficient d33 still suffers relatively higher deterioration, which indicates different characteristics for piezoelectric and ferroelectric fatigues. A possible mechanism of the partial pining of switching domains responsible for the difference is discussed in this paper.