Study On The Preparation Of Microwave Dielectric Ceramic Nano-titanium Zinc

Hexagonal close packing ZnTiO₃ is a very important microwave dielectric material. Its ordered structure is similar to Corundum, and its loss under microwave frequency is extremely low. It is provided with outstanding dielectric properties and low agglomeration temperature. It can be mixed with Ag, Cu, etc. to prepare electrodes at relatively low sintering temperatures. However, ZnTiO₃ is easily decomposed to Zn₂TiO₄ and TiO₂ 4 at temperature higher than about 945℃, which have low microwave frequency and Q value. Based on the requirements of miniaturization, low cost of the instruments and current problems in preparation of ZnTiO₃ ceramics, the study here first systematically optimized sol-gel forming conditions and sintering processes to get pure ZnTiO₃ powder at 850℃.Then, by adulterating Mg²⁺ to replace Zn²⁺ , (Zn,Mg) TiO₃ was synthesized, which kept stable under 1100℃.The details are as follows:1. The concentrations of the raw materials, adding order and pH value of the precursor solution affect the state of sol-gel greatly. After xerogel is under heat-treatment of 850℃for 5 hours, the main phase of the powder is ZnTiO₃ about 50 nm in size. But it still contains the phases of Zn₂TiO₄ of TiO₂2. Getting a single system of ZnTiO₃ powder by using second heat treatment. Xerogel was pr-etreated at 700℃for 5h and then heated to 850℃at rate10℃/min and kept for another 3h. By this way only pure phase of ZnTiO₃ was pepared.3.By adding Mg²⁺, the phase of ZnTiO₃ is stablized under high temperature. Moreover, as the quantity of Mg²⁺ increases, the thermal stability and purity of ZnTiO₃ increase too. By adding 30 (wt) % Mg²⁺, the powder can be sintered into ceramic at 1100℃and there is pure phase of ZnTiO₃. This kind of ceramic is even , dense and uniform and posseses good microwave dielectric properties as follows :ε_r = 27.1, Q×f = 59000GHz,Ï„f =-65ppm /℃.