掺杂氧化铌对钛酸锶钡铁电陶瓷材料显微结构和介电性能的影响

INFLUENCE OF NIOBIUM OXIDE ADDITIVE ON MICROSTRUCTURE AND DIELECTRIC PROPERTIES OF BARIUM STRONTIUM TITANATE FERROELECTRIC CERAMICS

钛酸锶钡(barium strontium titanate,BST)铁电陶瓷材料的介电常数(ε)随外加直流电场的变化呈现非线性特性。纯BST材料由于较高的ε和较大的介电损耗(tanδ)不能满足移相器介质材料的要求。通过在BST中添加氧化铌(Nb2O5)来改善BST铁电陶瓷材料的介电性能。结果表明:在BST体系中微量掺杂Nb2O5,Nb5+以取代Ti4+的方式存在于钙钛矿的晶格中,形成均匀的固溶体Ba0.5Sr0.5Ti1–xNbxO3。随Nb5+添加量的增加,Curie峰逐渐变宽,峰高逐渐降低,相变弥散效应增强。Nb5+的掺杂能显著降低并稳定BST陶瓷的tanδ,改善BST体系的介电性能。

Barium strontium titanate （BaxSr1-xTiO3, BST） is a solid solution ferroelectric material exhibiting a large dielectric constant non-linear change with an applied dc electric field. Pure BST can＇t satisfy the requirements of phase shifters due to its high dielectric constants and losses. It has been shown that the dielectric constants and losses of barium strontium titanate can be reduced by doping with certain oxides. Effects of niobium oxide （Nb205） on BST bulk ceramics were systematic studies. The results show that the Nbs＋ substitutes for Ti4＋ cation sites at the B positions of the ABO3 perovskite structure by adding Nb205 into BST bulk ceramics, and form a homogeneous solid solution. With the increase of Nb2Os-doping content, ferroelectric-paraelectric transition peaks become broa- dened, the maximum permittivity value decreases and the dispersion phase transition effect is enhanced. The proper quantity of Nb205 can significantly reduce and stabilize the dielectric losses, improving the dielectric properties of BST ceramics.