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Structural Evolution and Its Effects on Dielectric Loss in Sr1+xSm1−xAl1−xTixO4 Microwave Dielectric Ceramics

Authors

  • Min Min Mao,

    1. Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
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  • Xiao Qiang Liu,

    1. Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
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  • Xiang Ming Chen

    Corresponding author
    1. Laboratory of Dielectric Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China
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    • *Member, The American Ceramic Society.


  • P. Davies—contributing editor

  • The present work was financially supported by the Chinese National Basic Research Program under grant number 2009CB623302.

†Author to whom correspondence should be addressed. e-mail: xmchen59@zju.edu.cn

Abstract

The structural evolution of Sr1−xSm1+xAl1−xTixO4 (x=0, 0.05, 0.10, and 0.15) microwave dielectric ceramics was investigated together with its effects on dielectric loss. Through the analysis of Rietveld refinement of powder X-ray diffraction, the normalized bond length and normalized bond valence showed an abnormal variation of Sr/Sm–O(2b) and Al/Ti–O(2) bonds from x=0.10 to x=0.15. The abnormal variation related to these bonds in Raman spectra and IR reflectivity spectra was observed. IR reflectivity spectra were calculated by the classical oscillator model fitting to evaluate the intrinsic loss. The calculated Q × f value and the measured ones both decreased as x increased, and a sharp decrease from x=0.10 to x=0.15 was observed. The decreased tolerance factor should be responsible for the decreased Q × f value. Moreover, the abnormal evolution of Sr/Sm–O(2)–Al/Ti bonding that can cause an extra local stress should be responsible for the sharp decrease from x=0.10 to x=0.15 in Q × f value.

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