Microstructure evolution and properties of dissimilar YIG/MTC joint fabricated with bismuth-based glass ceramic

The paper uncovers microstructural evolution and bonding mechanism of yttrium iron garnet ferrite (YIG) and magnesium titanate ceramic (MTC) brazed by bismuth-based glass ceramic . The resulting mechanical and dielectric properties of the proposed YIG/MTC joint were investigated in detail. The reaction mechanism was thoroughly studied. Micro and nano CoFe 2 O 4 were generated in the glass seam. Besides, a CoFe 2 O 4 reaction layer was formed at the interface of MTC/glass ceramic. The atoms stacked along the plane (220), and a complete coherent boundary was emerged between the CoFe 2 O 4 reaction layer and MTC ceramic subsequently. YBO 3 clusters were formed at YIG/glass interface and Bi 9 Ti 3 Fe 5 O 27 stripe phases were generated in the glass matrix. The joint shear strength increased with the brazing temperature increasing, and reached a maximum value of 72 MPa at 800 °C. The dielectric constant of YIG/MTC joint varied from 16.5 to 17.9, and the dielectric loss tangent was nearly 0.001 at higher frequency.