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Fabrication and Dielectric Properties of LiTaO₃ Matrix Ceramics with Added Manganese Dioxide

Y. Yao, Y. Zhang

Journal of Ceramic Science and Technology, Vol. 11, No. 1 (2020), pp. 27-35

DOI: 10.4416/JCST2019-00053

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Abstract

Polycrystalline LiTaO3 ceramics are beset with difficulties with regard to fabrication by means of conventional pressureless sintering because of their own refractory character. In this study, composite ceramics of LiTaO3 with added manganese dioxide were obtained by sintering at 1 250 °C. The sinterability, microstructure and dielectric properties of the LiTaO3 composite ceramics were then investigated. The relative densities of the LiTaO3 composite ceramics were significantly improved by the addition of MnO2 powder. The LiTaO3 composite ceramics achieved the highest relative density (93.1 %) and obtained a well-grained microstructure when the amount of MnO2 added was 5 wt%. Only the LiTaO3 phase in the composite ceramics was observed when the MnO2 content added was less than 3 wt%. The second phase of the Mn3O4 particles existed in the boundaries of the LiTaO3 grains, and the content gradually increased when the mass fraction of added MnO2 was more than 3 wt%. The effects of the MnO2 added on the dielectric properties of the LiTaO3 composite ceramics are studied thoroughly herein. Consequently, the dielectric constant was found to be enhanced, and the dielectric loss decreased in the LiTaO3 composite ceramics with the MnO2 addition (i.e. both frequency- and temperature-dependent). The optimum values of the relative density, microstructure and dielectric properties were obtained when 5 wt% MnO2 was added to the LiTaO3 composite ceramics.

Keywords

LiTaO3 ceramics, manganese dioxide, microstructure, dielectric properties

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