Phenomenon and mechanism of ion diffusion at Co-fired joint interface of NiZn Ferrite/MCT ceramic heterostructure

Abstract

Nickel-zinc ferrite (NZF) discs and magnesium calcium titanite (MCT) dielectric ceramic discs were laminated and co-fired to prepare NZF/MCT bi-layer laminated heterostructure samples. The sintering shrinkage of NZF and MCT was matched well via adjusting the sintering temperature. Ion diffusion curves at the co-fired joint interface were derived by electron-probe microanalysis (EPMA) and fitted basing on infinite diffusion coupling model. Ion diffusion mechanism at the co-fired joint interface was investigated in detail. The results show that Zn2+ ions have the highest diffusion coefficient because of the smaller ion radius which is benefit for interstitial diffusion, while Ca2+ ions have the lowest diffusion coefficient and segregate along the interface of MCT side. Fe3+ ions have the biggest diffusion width because of the interstitial diffusion in the incompletely densified MCT. Sintered at 1260 °C, the maximum interdiffusion width is narrow to be about 102 μm. With increasing temperature, ion diffusion coefficient and diffusion distance both go up obviously.