A new strategy to fabricate YIG ferrite joint with novel magnetic Bi2O3-CoO-Fe2O3-B2O3 glass

A new low-temperature magnetic Bi 2 O 3 -CoO-Fe 2 O 3 -B 2 O 3 (BCFB) glass was designed to acquire magnetic yttrium iron garnet (YIG/YIG) joint. This paper investigated the thermal behavior of BCFB glass and its wettability on YIG. The microstructural evolution, mechanical and electromagnetic properties of YIG/YIG joint were systematically studied. CoFe 2 O 4 nuclei were gradually formed, growing up into nano-scale CoFe 2 O 4 crystals in the glass seam. Meanwhile, some CoFe 2 O 4 crystals grew up excessively by swallowing nano CoFe 2 O 4 , reaching microns. YBO 3 reaction layer was formed and grew into YBO 3 whiskers at the interface of YIG/glass with the brazing temperature increasing. The joint shear strength increased, reaching a maximum of 85.2 MPa at 775 °C under the collaborative reinforcement of well-integrated interface and glass-ceramic seam, then declined due to the aggravative reaction. The dielectric constant of YIG/YIG joints decreased with the brazing temperature increasing, varying from 18.5 to 16.6 at the frequency of 10 MHz. AFM/MFM and VSM analyses indicate that the glass seam performed magnetic property. The saturation magnetization of BCFB glass reached about 4.2 emu/g and 5.0 emu/g heat-treated at 750 °C and 775 °C, respectively, which could effectively enhance the magnetism of the glass seam.