Lifeng Cao

Effect of Co2O3 Additive on the Microstructures and Dielectric Properties of MgTiO3 Ceramics

(Mg 1 − x Cox)TiO 3 (x = 0, 0.03, 0.05, 0.1, 0.2) were synthesized by the solid-state reaction method. The effect of Co 2 O 3 additive on the microstructures, the phase formation and the microwave dielectric properties of MgTiO 3 ceramics was investigated. The microwave dielectric properties of the (Mg 1 − x Co x)TiO 3 ceramics system were found to vary with amount of Co 2 O 3 additive and sintering temperature which were attributed to the variation of second phase and densification of the ceramics. By properly adjusting the amount of Co 2 O 3 , a small dielectric loss of 0.2 × 10−4 was obtained for (Mg 1 − x Co x )TiO 3 ceramics.

Influence of Bi2O3 addition on structure and dielectric properties of Ag(Nb0.8Ta0.2)O3 ceramics

The structure and dielectric properties of perovskite Ag(Nb0.8Ta0.2)O3 ceramics were explored. A small amount of Bi2O3 was used to modify the dielectric properties of the ceramics. The addition of Bi2O3 led the ceramics to a high densification and optimal dielectric properties. With the addition of 4.5 wt% Bi2O3, the permittivity of Ag(Nb0.8Ta0.2)O3 ceramics increased from 470 to 733, the dielectric loss decreased from 62×10−4 to 6.7×10−4, and the temperature coefficient of capacitance, TCC, decreased from 2004 ppm/°C to −50 ppm/°C. The high permittivity obtained was due to the high densification and weak Ta-O or Nb-O bond strength in the oxygen octahedron that results from the addition of Bi2O3.

Structure and Dielectric Properties of Rare-Earth (La, Nd, Dy, Er) Substituted Ag(Nb,Ta)O3 Ceramics

(Ag 1 − y Ln y )(Nb 0.6 Ta 0.4 )O 3 + y (Ln = La, Nd, Dy, Er) ceramics were fabricated by the conventional solid-state reaction method. The microstructures, phase structures, and dielectric properties of the ceramics were investigated. The distortion of lattice was characterized by X-ray diffractometer. The grain sizes of rare-earth substituted ceramics were smaller than those of the pure sample. These results indicated that the rare-earth ions with various ionic radii entered the unit cell of the polycrystal, and inhibited the grain growth. Low dielectric loss was obtained due to the dense microstructure. Dependence of capacitance and dielectric loss on frequency illustrated the presence of polarization mechanism.