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Effect of SiO_2 Addition on Microwave Dielectric Properties of Ca_(0.61)La_(0.39)Al_(0.39)Ti_(0.61)O_3 Ceramics
摘要
The effects of SiO_2 addition on microwave dielectric properties of Ca_(0.61)La_(0.39)Al_(0.39)Ti_(0.61)O_3 ceramics prepared by a conventional solid‐state ceramic route were investigated. The x‐ray diffraction (XRD) results showed that all the samples with less than 2.0 wt% SiO_2 addition exhibited only a single phase Ca_(0.61)La_(0.39)Al_(0.39)Ti_(0.61)O_3 with tetragonal structure formed. Scanning electron microscopy (SEM) images of SiO_2 doping ceramics sintered at 1340 ℃ for 12h showed a compact microstructure. The silica entered the crystal lattice or was diffused to the interstitial sites in ceramic matrix causing the increase of the lattice parameters. SiO_2 addition formed the small ambiguous grains, which effectively lowered the sintering temperature. The SiO_2‐doped Ca_(0.61)La_(0.39)Al_(0.39)Ti_(0.61)O_3 ceramics have a low sintering temperature of 1340°C and a near zero τ_f value. Good microwave dielectric properties with a εr = 41.5, Q × f = 39,491 GHz and τ_f = -0.1 ppm/°C are obtained for 0.02wt% SiO_2 doped ceramics sintered at 1340 ℃ for 12h.