Low Temperature Sintering of Cu-substituted YIG

Abstract

Co-firing of YIG and conductors enables miniaturized, broadband isolators. The problem is that the conductors are melted in the co-fired body because firing temperatures of YIG are generally higher than the melting points of highly conductive metals like Ag. We have focused on Au as the conductor because it has the highest melting point among highly conductive metals. Then we have tried to reduce firing temperature of YIG by Cu-substitution. When a was 0.05 in (Ca_2xY_3-2x)(Fe_5-x-y-z-2αV_xAl_yIn₂Cu_αZr_α)O₁₂, the YIG was able to be fired at 1020°C, lower than melting point of Au (1064°C), with narrow ferromagnetic resonance as ΔH=33Oe. Accordingly it is achieved that sintering temperature is reduced by 60°C compared to the YIG at α=0. It is thought that Cu segregates at grain boundary, when α is larger than 0.05.