原料配方对移相器用BST陶瓷材料性能的影响

Effect of raw material composites on properties of BST ceramics

为了使钛酸锶钡（BST）铁电陶瓷应用于移相器,研究了原料配方和合成方法对钛酸锶钡（BST）铁电陶瓷的结构与性能的影响。以钛酸盐、碳酸盐和二氧化钛为原料进行组合,并掺杂改性物质,制备BST陶瓷,用XRD、SEM检测其晶相及显微结构,用闭腔法测量其微波介电性能。结果表明,不同原料或合成方法形成的BST陶瓷的晶相组成均相同,其中以钛酸钡、钛酸锶合成BST陶瓷的微波介电性能最佳。添加质量分数60%MgO和少量La2O3的（Ba0.6Sr0.4）TiO3的介电性能为：εr=96.6,Q·f=1 155 GHz,T=9.5%（2×10^3 V/mm）,τf=2.5×10^-3/℃,满足移相器对BST材料的要求。用该组成设计了3节阻抗匹配的360°铁电体移相器,8-12 GHz范围内,插入损耗小于3 dB,电压驻波比小于1.5。

In order to make barium strontium titanate（BST） ferroelectric ceramic to be used for phase shifters, the effects of raw material and synthesis on the structure and properties of BST ceramic have been investigated. Titanate, carbonate and titanium dioxide were selected to prepare BST ceramics doped modifiers. The crystalline phases and microstructures were detected with X ray diffraction and scanning electron microscope. The microwave dielectric properties were measured with closed cavity method. The results have indicated that the crystalline phases for all ceramics, which were prepared with different raw materials and synthesis, are the same. When barium titanate and strontium titanate were selected, the microwave dielectric properties of BST ceramic is the best. The microwave dielectric properties of BST ceramic doped with 60 percent magnesium oxide and a little lanthanum oxide are listed： εr= 96.6, Q·f =1 155 GHz, T=9.5%（2×10^3 V/mm）, τf=2.5×10^-3/℃, which is better candidate material for phase shifters. A 360-degree ferroelectric phase shifter with 3-section impedance matching devices is designed with BST ceramics. In the frequency range from 8 GHz to 12 GHz, the insert loss is less than 3 dB, voltage standing wave ratio less than 1.5.