The effect of growth atmosphere and Ir contamination on electric properties of La3Ta0.5Ga5.5O14 single crystal grown by the floating zone and Czochralski method
The influence of growth atmosphere and Ir contamination on electrical resistivity of langatate (La3Ta0.5Ga5.5O14; LTG) was studied. LTG single crystals were grown via the Czochralski method under different oxygen partial pressures with Ir contamination from the Ir crucible. In addition, LTG crystals were grown by the floating zone method and they were not contaminated by Ir. The electrical resistivity and ionic transport number of these crystals were measured in the temperature range 300–1000°C. The conduction mechanism of LTG changed at about 720°C. At T < 720°C, electronic conduction was dominant, and the resistivity was affected by growth atmosphere as well as Ir contamination. In contrast, at T > 720°C, ionic conduction was dominant, and the resistivity was affected only by Ir contamination. In both temperature regions, Ir contamination decreased the resistivity by an order of magnitude.
KeywordsLangatate Piezoelectric material Electrical resistivity High temperature Defect
This work was supported in part by Grants-in-Aid for Scientific Research (17360002) from the Ministry of Education, Science, Sports and Culture of Japan. We also would like to thank the Nano-Materials Project of IMR, Tohoku University, and Mitsubishi Foundation for their support.
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