以Na2O5作为起始物,通过热碱反应与钽离子反应,通过浓度控制,清除钠离子工艺后,得到优质Na2O5·nH2O胶体;然后与Ba,Mg醋酸盐计量混合得到凝胶,经820℃,1 h热处理后,制得BMT纳米粉末,进一步烧结后得到BMN纳米陶瓷,其相致密度达到98.2%,微波介电性能Q=10397(频率1.45GHz).运用量子化学SCF-Xa-SW法对Ba(B'1/3B''2/3)O3复杂钙钛矿结构进行电子结构分析,计算表明离子结合强度是Ba(Mg1/3Nb2/3)O3和BaTiO3结构稳定的关键参数,BMN中B位氧离子和阳离子的结合强度远高于BaTiO3,而且BMN的非平衡力导致B位离子在某一定方向有序化排列,这种有序结构导致A(B',B'')O3材料比ABO3材料更具优良的介电性能,并得到实验验证.因此有助于高品质因数微波介质陶瓷的设计和制备.
A novel sol-gel process for preparing Ba(Mg1/3Nb2/3)O3(BMN)nanopowders and a characteristic for the electronic structure using the quantum chemical SCF-Xa-SW method were described.The ultrafine BMN powders were finally obtained after heat-treating the gel at 820℃for 1 h,and the nanoceramics revealed a high relative density of 98.2%,and a high Q-factor(one of microwave properties)of 10397 at 1.45GHz.The electronic structure of BMN as a typical example of Ba(B'1/3B''2/3)O3 complex perovskites has been investigated using the quantum chemical SCF-Xa-SW method.It is found that the bonding strength between oxygen and cations of B-site in BMN are greater than that in BaTiO3,and the unbalance force in BMN lead to the tendency of B-site ion arranging orderly.
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