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Ag2 MoO4 ceramic was prepared by using the solid-state reaction method, which could be sintered at 450°C for 2 h, having a relative permittivity of 8.08, a Qf value of 17 000 GHz, and a temperature coefficient of resonance frequency about −133 ppm/°C. Ag2 MoO4 ceramic was chemically compatible with silver but reacted seriously with aluminum to form ( Ag0.5 Al0.5) MoO4 during the sintering. The fitting of infrared spectra and the Shannon's additive rule were employed to study intrinsic dielectric behaviors of the ceramics at microwave region. Ionic displacive polarization and the electronic polarization contributed almost equally to the dielectric permittivity of the ceramic at microwave region. The Ag2 MoO4 ceramics could be a good candidate for ultra-low temperature co-fired microwave devices. [ABSTRACT FROM AUTHOR]

In the present work, ( Bi1− x Fe x) VO4 ( x ≤ 0.40) ceramics were prepared using the solid-state reaction method. All the ceramics could be well densified at sintering temperatures below 800°C. X-ray diffraction ( XRD) results showed that monoclinic solid solution was formed within x ≤ 0.08. When x ≥ 0.10, both monoclinic scheelite and FeVO4 phases were detected. The ( Bi0.92 Fe0.08) VO4 sample sintered at 720°C for 2 h had a permittivity of 57.5 and a Qf value of 15 000 GHz. The IR reflectivity was fitted to study the intrinsic dielectric properties, showing that the majority of the dielectric contribution for this system at microwave region was attributed to the absorptions of structural phonon oscillation in infrared region. [ABSTRACT FROM AUTHOR]

The effects of CuO, Bi2O3 and V2O5 additions on the microstructure and the microwave dielectric properties of ZnNb2O6 ceramics were investigated systematically. The sintering temperature of ZnNb2O6 ceramics with CuO, Bi2O3 and V2O5 (CuBiV) additions can be effectively reduced from 1150 to 890 °C. The presence of CuBiVZn-rich intergranular phase in the specimen was observed and was evidence of the formation of a liquid phase during sintering. The 1.5 wt.% CuBiV-doped ZnNb2O6 ceramics sintered at 890 °C have the optimum microwave dielectric properties. [Copyright &y& Elsevier]

Abstract: The dielectric properties of BZT ceramics with different Zr contents and donor types are studied. It is shown that the large enhancement of the dielectric permittivity is achieved accompanying with the remarkable shift of Curie temperature in the samples doped with donors such as La, Nd, Sm, Eu, Dy, and Yb, whereas the results are different in them doped with other type of donors such as Ce and Y. The shift of Curie temperature is related to the ionic radii of the doped donors. A smaller ion results in a greater shift. The dielectric properties of BZT with different doping levels of Yb are also studied and showed that there is a preferable doping content as Yb ∼0.1% to make the material with the highest permittivity, ɛ ∼25,800, withstand voltage >∼3.5 kV/mm. [Copyright &y& Elsevier]