Patent ID: 8546699

Claim:
A glass-ceramic substrate comprising: a glass-ceramic layer comprising: a glass phase; and a glass comprising a first crystal; a ferrite layer comprising a ferrite crystal; and an interlayer between the glass-ceramic layer and the ferrite layer, the interlayer comprising a second crystal having a crystal structure isomorphic to a crystal structure of the first crystal and a crystal structure of the ferrite crystal, wherein the first crystal comprises Mg 2 SiO 4 , the ferrite crystal comprises FeFe 2 O 4 , and the second crystal comprises at least one of ZnFeO 4 , FeAl 2 O 4 , and ZnAl 2 O 4 , a difference in lattice constants between the second crystal and the ferrite crystal is at most about 10% of a lattice constant of the second crystal, and a difference in lattice constants between the second crystal and the first crystal is at most about 10% of the lattice constant of the second crystal.