介电陶瓷/NiZn铁氧体互扩散行为的第一性原理研究

First-principles Study of Diffusion Behavior between Dielectric Ceramics and NiZn-ferrite

针对介电陶瓷/NiZn铁氧体异质复合材料的低温共烧陶瓷体系,建立掺杂结构模型,采用基于密度泛函理论的第一性原理计算并结合CI-NEB方法研究阳离子互扩散机制。结果表明:铁氧体中的Ni,Zn,Fe离子主要取代介电陶瓷MgTiO_(3)和CaTiO_(3)体系中的Ti位,迁移势垒1.0~5.5 eV;对于介电陶瓷Mg和Ca倾向于占据NiZnFe_(4)O_(8)中Zn位点,Ti则倾向于取代Fe位,迁移势垒0.6~1.0 eV。对于该材料体系,典型共烧工艺条件下Ca,Mg扩散进入NiZn铁氧体距离400~1000μm。

For the low temperature co-fired ceramic system of the dielectric ceramic and NiZn-ferrite,the doping model is established,and the cation mutual diffusion mechanism is studied by using the first-principles calculation based on the DFT and CI-NEB method.The results show that Ni,Zn and Fe in ferrite mainly replace the Ti in the dielectric ceramic MgTiO_(3)and CaTiO_(3),and the migration barrier is1.0-5.5 eV;For dielectric ceramics,Mg and Ca tend to occupy the Zn site in NiZnFe_(4)O_(8),while Ti tends to replace the Fe site,and the migration barrier is 0.6-1.0 eV.For this material system,under typical cofiringprocess conditions,Ca and Mg diffuse into NiZn ferrite at a distance 400-1000μm.