磁性微晶玻璃连接锂铁氧体接头组织演变及磁性能模拟

The glass joining technology of lithium ferrite can overcome the difficulty that the conventional sintering method cannot manufacture microwave ferrite components with complex structures, and the glass-ceramic can precipitate the in-situ magnetic microcrystalline phase in the ferrite joint, thereby realizing the structure-function integration of connected components. The glass-ceramics (LFBi5B,LFBi15B,LFBi25B) are designed for the joining of ferrite. The wettability of glass-ceramic, the effect of glass-ceramic composition and bonding temperature are studied, as well as the source of magnetism in the joint seam. The results show that the three glass-ceramics perform favorable wettability on YIG substrate. LiFeO₂ crystals are precipitated in situ in the joint. Some of the precipitated crystals dissolve with the temperature increasing. A small amount of bismuth titanate whiskers are generated. The simulation via the first-principle indicates that the total magnetic moment of the crystal is not equal to 0, the upper and lower spin energy bands are asymmetric, and the state density diagram shows the spin-split state, which proves that the LiFeO₂ crystal owns magnetism. The magnetism results from the exchange of electrons in the p and d states of Fe and O atoms. This investigation combines experiment and theory, realizing the in-situ growth of magnetic LiFeO₂ microcrystals in YIG joint brazed by glass-ceramic, meanwhile verifying the magnetic source, which provides a new idea for the integrated design of structure and function of magnetic joints.