Phase analysis and dielectric properties of oxides obtained in the MgO-(1-x)Nb2O5-(x)Ta2O5 system

Thirumal, M. ; Ganguli, A. K. (2001) Phase analysis and dielectric properties of oxides obtained in the MgO-(1-x)Nb2O5-(x)Ta2O5 system Journal of Chemical Sciences, 113 (5&6). pp. 603-610. ISSN 0253-4134

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Official URL: http://www.ias.ac.in/chemsci/Pdf-OctDec2001/Pc3099...

Related URL: http://dx.doi.org/10.1007/BF02708793

Abstract

MgNb2-xTaxO6 (0 ≤x ≤2) phases can be obtained as the major phase (75 to 90%) by solid state reactions starting from oxides. These oxides crystallize in the orthorhombic columbite structure till x=1·75 and the tetragonal trirutile structure for MgTa2O6 (x = 2·0). For all the compositions there exist secondary phases like Nb2O5 or Ta2O5 in addition to the major AB2O6 phase. Sintered disks (1200°C) show dielectric constants varying between 14·8 and 16·0 for the entire range of composition at a frequency of 500 kHz. The dielectric loss is nearly constant around 0·025 to 0·03 between 0 ≤x ≤ 1 but increases to 0·17 for the MgTa2O6 phase (x= 2·0). Scanning electron micrographs reveal a gradual decrease in grain size with increase in Ta concentration with a size of 3 micron forthe x=0 composition (sintered at 1200°C) while the x=2 phase shows a grain size of approximately 0·5 microns. The microwave dielectric constant at ~14 GHz is found to be 20·9 for the x=0 composition and 17·7 for the x=2 composition.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Ceramics; Electronic Materials; Oxides
ID Code:62040
Deposited On:16 Sep 2011 03:48
Last Modified:18 May 2016 11:29

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