Study Of Modified (Zr_0.8, Sn_0.2) TiO₄ Dielectric Ceramics

Microwave ceramics is a new functional ceramics that quickly developed in late ten years. It takes the circuit effect such as dielectric isolation, dielectric waveguide and dielectric resonance on the microwave circuit, and plays an important role in miniaturization, integration and high quality factor of microwave circuits. (Zr_0.8,Sn_0.2) TiO₄ microwave dielectric ceramics is titanate materials with outstanding property and widely application.There is little study about the effect of microstructure on dielectric property of microwave dielectric ceramics. But it is very difficult to get the relationship between dielectric properties and structure at microwave frequency. It is important to make sure the relationship between dielectric properties and structure under the condition of low frequency.Microwave dielectric ceramics were prepared with ZrO₂, SnO₂, TiO₂ as raw material, CuO,ZnO as sintering aids, and Li⁺, Mg²⁺, Ni²⁺, Sb³⁺, Bi³⁺, Nb⁵⁺as additives. The phase structure and the microstructure were characterized by X ray diffraction and scanning electron microscope. Dielectric properties were tested by Agilent 4284 resistance analytical equipment, and conductivity were tested by EST121 high megohm small current testing instrument. The preparation technology, dielectrics and microstructure of (Zr_0.8,Sn_0.2 TiO₄ ceramics were systematically study .The chief contents as following: 1. The sintering temperature of ( Zr_0.8,Sn_0.2 )TiO₄ ceramics can be reduced using ZnO/CuO as sintering aids. The dielectric properties of (Zr_0.8,Sn_0.2) TiO₄ ceramics with different ratio of ZnO/CuO at the sintering temperature 1150℃were studied carefully.ε_r =37.1, tgδ=4×10^-4,when ZnO and CuO was 3%wt at 1MHz.2. Different additives (Li⁺, Mg²⁺, Ni²⁺, Sb³⁺, Bi³⁺, Nb⁵⁺) were doped in (Zr_0.8,Sn_0.2) TiO₄ ceramics. Microstructure and dielectric properties werestudied. The results showed that ionic radius, electronegativity and polarization effected on phase structure, microstructure and dielectric properties. The second phase did not appear when the content of Li⁺ Ni²⁺, Bi³⁺, Nb⁵⁺ is low. The second phase were appeared when the content of Mg²⁺, Ni²⁺, Sb³⁺ is 0.05mol .The grain size decreased with the increasing of the content of additives .Maximum dielectric constant is SO when the content of Bi³⁺is 0.2mol.