Origin of Microwave Dielectric Loss in ZnNb2O6-TiO2

Authors

  • Dong-Wan Kim,

    1. School of Materials Science and Engineering, College of Engineering, Seoul National University, Seoul, Korea
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  • Kyung Hyun Ko,

    1. School of Materials Science and Engineering, College of Engineering, Seoul National University, Seoul, Korea
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    • *

      Member, American Ceramic Society.

    • Department of Materials Science and Engineering, Ajou University, Suwon, Korea.

  • Do-Kyun Kwon,

    1. School of Materials Science and Engineering, College of Engineering, Seoul National University, Seoul, Korea
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  • Kug Sun Hong

    1. School of Materials Science and Engineering, College of Engineering, Seoul National University, Seoul, Korea
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  • P. K. Davies—contributing editor

  • This work was supported in part by the Ministry of Information and Communi-cation of Korea (“Support Project of University Foundation Research <2000>” supervised by the Institute of Information Technology Assessment).

Abstract

(1−x)ZnNb2O6·xTiO2 ceramics were prepared using both anatase and rutile forms of TiO2. At a composition of x= 0.58, a mixture region of ixiolite (ZnTiNb2O8) and rutile was observed and the temperature coefficient of resonant frequency (τf) was ∼0 ppm/°C. We found that although ɛr and τf were comparable, the quality factor (Q×f, Q≈ 1/ tan δ, f= resonant frequency) of 0.42ZnNb2O6·0.58TiO2 prepared from anatase and rutile was 6000 and 29 000, respectively. The origin of the difference in Q×f of both samples was investigated by measuring electrical conductivity and by analysis of the anatase–rutile phase transition. The anatase-derived sample had higher conductivity, which was related to the reduction of Ti4+. It is suggested that the increase of dielectric loss originates from an increase in Ti3+ and oxygen vacancies due to an anatase–rutile phase transition.

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