BaAl2-2xMg2xSi2O8陶瓷制备与微波介电性能研究

Preparation and Microwave Dielectric Properties of BaAl2-2xMg2xSi2O8 Ceramics

通过固相烧结法制备了BaAl2-2xMg2xSi2O8(x=0,0.005,0.01,0.02,0.03)陶瓷,研究了不同Mg^2+取代量对BaAl2Si2O8(BAS)系陶瓷晶体结构和介电性能的影响。利用基于第一性原理的CASTEP计算了Mg掺杂BAS不同位置的形成能能和总能量。结果表明Mg应当进入Al位,Mg^2+取代Al^3+生成的氧空位可以促进BAS转变为单斜相,从而改善样品的密度、品质因素(Q×f)及谐振频率温度系数(τf)。x=0.005时,样品经1500℃烧结后表现出最佳的介电性能:εr=6.74,Q×f=36125 GHz,τf=-26.97×10-6/℃。

BaAl2-2xMg2xSi2O8(x=0,0.005,0.01,0.02,0.03)ceramics were fabricated by solid state sintering.The effects regarding different Mg^2+substitutions on the crystal structure and dielectric properties of BaAl2Si2O8(BAS)microwave dielectric ceramics were investigated.The formation energy and total energy of Mg-doped different positions were calculated by CASTEP software based on first principles.The result suggests that Mg should enter the Al-Site.The oxygen vacancies formed by the substitution of Mg^2+for Al3+are favorable to facilitating BAS transforming into monoclinic phase,which enhanced the density,as well as quality factor(Q×f)and temperature coefficient of resonant frequency(τf)of BAS ceramics.When x=0.005,the sample sintered at 1500℃demonstrated the best dielectric properties:εr=6.67,Q×f=36125 GHz,τf=-26.97×10^-6/℃.