Patent ID: 7476482

Claim:
An Mg-based ferrite material consisting essentially of X 2 O n , MgO and Fe 2 O 3 components or of X 2 O n , CaO, MgO and Fe 2 O 3 components, and having a composition of formula (1): X a Mg b Fe c Ca d O e (1) wherein X is Li, Na, K, Rb, Cs, Sr, Ba, Y, La, Ti, Zr, Hf, V, Nb, Ta, Al, Ga, Si, Ge, P, Sb, Bi or a combination thereof; and a, b, c and d satisfy 0.001≦R(X)≦0.15 wherein R(X) is represented by the formula: R(X)= a ×( Aw (X)+( n /2)× Aw (O))/( a ×( Aw (X)+( n /2)× Aw (O))+ b×Fw (MgO)+( c /2)× Fw (Fe 2 O 3 )+ d×Fw (CaO)); Aw(X) and Aw(O) are an atomic weight of X and an atomic weight of O, respectively; n is an oxidation number of X; and Fw(A) is a formula weight of A, 0.01 ≦b /( b+c /2)≦0.85 and 0≦R(Ca)≦0.15 wherein R(Ca) is represented by the formula: R(Ca)= d×Fw (CaO)/( a ×( Aw (X)+( n /2)× Aw (O))+ b×Fw (MgO)+( c /2)× Fw (Fe 2 O 3 )+ d×Fw (CaO)); wherein Fw(A) is the same as defined in R(X), e is determined by the oxidation numbers of X, Mg, Fe and Ca; wherein the Mg-based ferrite material has a dielectric breakdown voltage in the range of 1.5-5.0 kV; and wherein the Mg-based ferrite material has a saturation magnetization in the range of 30-80 emu/g measured at 14 kOe using a vibrating sample magnetometer.