In this study, a disk-shaped step-down piezoelectric transformer that consists of Mg:LN single crystals operating in the extensional vibration mode was proposed, and its characteristics wre investigated. This paper proposed the PT using ring/dot electrode which had an outer diameter of 22 mm, a narrow annular gap circle of 1.0 mm and a thickness of 1.0 mm. The transformer was poled along the thickness direction. The top surface was covered by two ring-shaped electrodes separated by a narrow annular gap, and the regions covered by the outer and inner ring electrodes serve as the output and input parts of the transformer, respectively. The bottom surface was fully covered with a gold electrode. Moreover, according to the physical equivalent circuit model of the latest invented vibration mode, PT of Mg:LN single crystals were fabricated and characterized. Finally, we investigated the gain under different load resistances and input voltage.

Sapphire crystals grown by an improved Kyropoulos-like method were irradiated by gamma rays and electrons in this paper. Thermoluminescence (TL) and optical stimulated luminescence (OSL) properties of sapphire were studied. TL glow curves of sapphire were varied within the room temperature to 500°C at a heating rate of 10min•s-1. The OSL spectra wavelength covered were from 200nm to 700nm. There was a new peak at 220°C, which was produced by the irradiation of gamma rays and electrons. Two broad bands at 330nm and 410nm were found in the luminescence spectra, which were due to transitions of two charge states of an anion vacancy defect, corresponding to F+ and F color centers, respectively.