Control of 0.2CaTiO3-0.8Li0.5Nd0.5TiO3 microwave dielectric ceramics by additions of Bi2Ti2O7 |
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Authors: | T Lowe F Azough R Freer |
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Affiliation: | (1) Materials Science Centre, School of Materials, University of Manchester, Manchester, M1 7HS, UK |
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Abstract: | Ceramics of 0.2CaTiO3-0.8Li0.5Nd0.5TiO3) have been prepared by the mixed oxide route using additions of Bi2O3-2TiO2 (up to 15 wt%). Powders were calcined 1100∘C; cylindrical specimens were fired at temperatures in the range 1250–1325∘C. Sintered products were typically 95% dense. The microstructures were dominated by angular grains 1–2 μm in size. With increasing
levels of Bi2O3-2TiO2 additions, needle and lath shaped second phases developed. For Bi2Ti2O7 additions up to 5 wt%, the relative permittivity increased from 95 to 131, the product of dielectric Q value and measurement frequency increased from 2150 to 2450 GHz and the temperature coefficient of resonant frequency (τ
f
) increased from −28pp/∘C to +22pp/∘C. A product with temperature stable τ
f
could be obtained at ∼2 wt% Bi2Ti2O7 additions. For high levels of additives, there is minimal change in relative permittivity, the Qxf values degrade and τ
f
becomes increasingly negative. |
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Keywords: | Perovskite CaTiO3 Microwave dielectric Electron BackScatter Diffraction (EBSD) |
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