【摘要】 对Ba4.5(Nd0 .84,Bi0 .1 6 ) 9Ti1 8O54 (BNBT)系微波陶瓷进行了组成改性的研究。添加不同量的SrO或SnO2 于主相材料中 ,分别替代Ba或者Ti,合成条件为 110 0℃下保温 3h ,粉碎、成型后 ,在 12 70℃下保温 3h烧成。在 10GHz下用谐振腔法测量了材料的介电常数εr和机械品质因数Q ,在 2 0～ 90℃范围测量了频率温度系数τf。结果表明 :Sr,Bi复合掺杂能够使BNBT材料保持较高的介电常数 ,同时Qf值 (机械品质因数Q与测量频率之积 )由 5 899GHz上升到 92 5 9GHz,而少量的SnO2 添加有助于提高系统的介电常数并使τf值减小更多还原

【Abstract】 The microwave dielectric properties and microstructure of Ba 4.5(Nd 0.84,Bi 0.16) 9Ti 18O 54(BNBT) ceramics with SrO or SnO 2 additives were investigated. BNBT precursor powders doped with different contents of SrCO 3or SnO 2 for the substitution of Ba or Ti were synthesized at 1 100 ℃ for 3h and then BNBT samples were sintered at 1 270 ℃ for 3 h. The dielectric constant ε r and the quality factors Q were measured at 10 GHz by using resonance cavity method and the temperature coefficients of resonant frequency were also measured in the temperature range of 20-90 ℃. Experimental results indicate that the substitution of 0.04 mol Sr ions for Ba ions can improve Qf values from 5 899 GHz to 9 259 GHz and keep high dielectric constant. It is explained that the substitution reduces the inner strain, which is caused by the larger Ba ions occupying the sites in the perovskite blocks for Nd ions, because the ionic radius of the Sr ion is smaller than that of the Ba ion. The doping with small amount of Sn is helpful to decrease τ f from 28.7×10 -6/K to 13.5×10 -6/K and improve dielectric constant by substitution of Sn ion for Ti ion at the site of Ti-O octahedral, which results in the increase of cell volume of the tungsten bronze-type structure.更多还原