Article abstract
Nature Materials 2, 541 - 545 (2003)
Published online: 13 July 2003 | doi:10.1038/nmat939
Subject Categories: Ceramics | Electronic materials | Characterisation and analytical techniques | Computation, modelling and theory
Identification of ultradilute dopants in ceramics
Isao Tanaka1,2, Teruyasu Mizoguchi1, Masafumi Matsui1, Satoru Yoshioka1, Hirohiko Adachi1, Tomoyuki Yamamoto2, Toshihiro Okajima3, Masanori Umesaki3, Wai Yim Ching4, Yoshiyuki Inoue5, Masataka Mizuno5, Hideki Araki5 & Yasuharu Shirai5
Abstract
The properties of ceramic materials are strongly influenced by the presence of ultradilute impurities (dopants). Near-edge X-ray absorption fine structure (NEXAFS) measurements using third-generation synchotron sources can be used to identify ultradilute dopants, provided that a good theoretical tool is available to interpret the spectra. Here, we use NEXAFS analysis and first-principles calculations to study the local environments of Ga dopants at levels of 10 p.p.m in otherwise high-purity MgO. This analysis suggests that the extra charge associated with substitutional Ga on a Mg site is compensated by the formation of a Mg vacancy. This defect model is then confirmed by positron lifetime measurements and plane-wave pseudopotential calculations. This powerful combination of techniques should provide a general method of identifying the defect states of ultradilute dopants in ceramics.
- Department of Materials Science and Engineering, Kyoto University, Sakyo, Kyoto 606-8501 Japan
- Fukui Institute for Fundamental Chemistry, Kyoto University, Sakyo, Kyoto 606-8103 Japan
- SPring-8 / Japan Synchrotron Radiation Research Institute (JASRI), Sayo, Hyogo 679-5198, Japan
- Department of Physics, University of Missouri Kansas-City, Missouri, 64110-2499, USA
- Department of Materials Science and Engineering, Osaka University, Suita, Osaka, 565-0871, Japan
Correspondence to: Isao Tanaka1,2 e-mail: itanaka@MTL.kyoto-u.ac.jp
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