A single-phase Sr-Nd-Co M-type ferrite fine particles have been produced by the chemical coprecipitation and heat treatment method for the sample having a formula {(SrO⋅n/2(Fe₂O₃))}_100-x-y(Nd₂O₃)_x(CoO)_y (n = 7.0, x= 1.0-10.0, y =1.0-10.0). The chemical reagents used are FeCl₃⋅6H₂O, SrC1₂⋅6H₂O, NdC1₃⋅6H₂O, and CoCl₂⋅6H₂O. A solution containing Sr²⁺, Fe³⁺, Nd³⁺, and Co²⁺ is poured into a solution of NaOH (pH=13.0).
Then the precipitated products are boiled for 2 h and they are carefully washed and dried. The obtained fine particles are heated at a temperature between 950 and 1100°C for 2h in air to get a single-phase Sr-Nd-Co M-type ferrite fine particles. The most prominent magnetic properties have been observed for the sample with the compotion of { SrO⋅3.5(Fe₂O₃) }_94.0(Nd₂O₃)2.0(CoO)_4.0; they are as follows: σ_s=89.5 × 10^-6 Wb⋅m/kg (71.2 emu/g), σ_r=45.3 × 10^-6 Wb⋅m/kg (36.0 emu/g), H_cJ=490.0 kA/m (6.16 kOe), α (σ_r) =-0.20 %/°C, α (H_cJ)=0.08 %/°C and T_c=465.3°C.