Mg添加ZnOの誘電的性質

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The crystal structure and dielectric property in Mg-doped ZnO were studied to clarify the mechanism of the ferroelectric phase transition observed in Li-doped ZnO. An Mg^<2+> ion has almost the same radii as Li^+ ion. By using a formula of Mg_XZn_<I-X>O, the ceramics samples with X=0.05, 0.10, 0.15 and 0.20 were synthesized. The amount of Mg atom substituting the Zn atom in each X was calculated from the amounts of Mg in the sample obtained by EPMA (Electron Probe Micro-Analyzer) and that of residual MgO obtained by X-ray diffraction. The residual MgO was detected in the sample with X more than 0. 10. The dieletcric constant vs temperature curve obtained in the Mg-doped ZnO has two characteristic peaks. The first peak observed at about 370K in the heating process is high and broad, which is considered due to a photoelectric effect in a semiconductor. The second one observed at about 480K in both heating and cooling processes is small, which is considered to be a dielectric anomaly with the ferroelectric phase transition. That is confirmed by the D-E hysteresis roops in the sample with X=0.10 and 0.15.
函館工業高等専門学校の論文