Nb_2O_5掺杂NiFe_2O_4陶瓷材料的显微结构和导电性能

Microstructure and electrical properties of Nb_2O_5-doping NiFe_2O_4 ceramic

以NiO、Fe2O3和Nb2O5为原料,采用固相烧结法合成陶瓷粉体,通过等静压-气氛烧结法制备Ni1-xNbxFe2O4(x=0,0.02,0.05,0.07,0.10,0.20)陶瓷试样,并对其进行导电性能测试。通过XRD、SEM、EDX、FTIR和XPS等分析手段对材料的物相组成、显微结构和微区成分进行表征,研究Nb2O5掺杂对陶瓷材料显微结构和导电性能的影响。结果表明:Nb2O5掺杂抑制NiFe2O4基体中NiO相的出现,过量时生成FeNbO4相;适量掺杂(x=0.05)有利于消除晶界孔隙,提高陶瓷的烧结密度;与未掺杂试样相比,掺杂Nb2O5的NiF2O4陶瓷材料的导电性均得到很大改善,其中掺杂量x=0.05的Ni0.95Nb0.05Fe2O4陶瓷试样在1 233 K的电导率较纯NiFe2O4的提高60%。

The ceramic powders were synthesized by solid-state reaction method asing nickel oxide, ferric oxide and niobium oxide as raw materials, and the Ni1-xNbxFe204 （x=0, 0.02, 0.05, 0.07, 0.10 and 0.20） ceramic were prepared by isostatic pressing-atmosphere sintering method. The electronic conductivity of ceramics was tested. The phase composition, microstructure and microarea composition of ceramics were analyzed by XRD, SEM, EDX, FTIR and XPS. The effects of Nb2O5-doping on the microstructure and electrical properties of ceramics were investigated. The results show that the appearance of NiO phase in NiFe2O4 matrix is restrained during Nb2O5-doping. And an impurity phase of FeNbO4 appears while excessive Nb2O5 is added. The right amount of doping （x=0.05） helps to eliminate the pores in grain boundaries and improves the sintering density of ceramics. Compared with the undoped samples, the conductivity performances of doped sample have been greatly improved. The conductivity of Ni0.95Nb0.05Fe204 sample increases by 60% compared with that of the undoped samples at 1 233 K.