驰豫型铌镁酸钡的制备及微波性能研究

Study on the preparation and microwave properties of Ba(Mg,Nb)O_3 ceramics

采用氧化物混合法制备了铌镁酸钡Ba(Mg1/3,Nb2/3)O3(BMN)和Ba1-xLax(Mg1/3,Nb2/3)O3(BLMN)驰豫型铁电陶瓷。通过XRD和SEM分析发现,Ba(Mg1/3,Nb2/3)O3陶瓷进行La掺杂有利于钙钛矿相颗粒的晶化度改善,而且掺La量的增加促进了晶粒的细化和均匀化。这是由于La的引入使钙钛矿结构的对称性降低,晶格畸变严重,抑制了晶粒的长大。烧结温度为1 400℃,保温时间3 h时,BMN介电常数达到了32.8。La的掺杂量为0.02%时,BLMN的品质因数(Q×f)值为32 300,体系的微波性能得到了明显改善。

Ba（ Mg1/3, Nb2/3 ） O3 （BMN） and Ba1-xLa （ Mg1/3, Nb2/3 ） O3 （BLMN） relaxor ferroelectric ceramics were prepared by the oxides-mixing method. By XRD and SEM techniques, the crystallization degree increases with increasing the amount of La for the Ba（ Mg1/3, Nb2/3 ） 03 perovskite phase. With the La doping, the grain size of Ba （ Mgl/3 ,Nb2/3 ） 03 perovskite phase becomes more uniform and fine, which attributed to lowering of perovskite structure symmetry and lattice distortion. The dielectric constant of BMN is 32.8 at sintering temperature of 1 400 °C when sintering time is 3 h. The Q xf value of BLMN is 32 300 when La doping concentration is 0. 02%. The microwave property of BMN is significantly improved with La doping amount of 0. 02%.