Interface and ionic interdiffusion in cofired dielectrics/ferrite layer composites

Zinc-magnesium titanate dielectrics/nickel-zinc-copper ferrite layer composites were prepared. An interlayer was designed to relax the interfacial stress because of the mismatch shrinkage between dielectric and ferrite. And as the results, zero camber and crack-free dielectric/interlayer/ferrite composite samples were obtained and the interface was continuous with no delamination. The cofiring interface and ionic interdiffusion between the constituents were investigated. The interdiffusion of the composite can be regarded as the semi-infinite diffusion-couple model and based on this diffusion model, the numerical simulation for the ionic composition distribution was carried out by computer, which was in agreement with the experimental results. The activation energies for the Ti⁴⁺, Ni²⁺, and Fe³⁺ were determined respectively. The difference between apparent activation energies was discussed in this article. The layer composite sintered at 930°C exhibited the dielectric properties: ?? _r ?=?18.2, tan???=?3.01?×?10^?3. Due to their low firing characteristics and realizable co-firing compatibility, the layer composites can serve as the promising medium materials in the multilayer LC filter.