Effect of cation substitutions in Y-type Ba_0.5Sr_1.5Me₂Fe₁₂O₂₂ hexaferrites on the magnetic phase transitions

Abstract We investigated the magnetic properties and magnetic phase transition in Y-type Ba0.5Sr1.5NiMgFe12O22 hexaferrite powder prepared by citrate sol-gel spontaneous combustion. The saturation magnetisation value of 32 emu/g at 4.2 K was lowered to 24 emu/g at 300 K. The magnetisations curves did not saturate even at a magnetic field of 50 kOe for both temperatures - 4.2 K and 300 K. A step-like behaviour appeared in the initial magnetisation curve at 4.2 K. A magnetic phase transformation from a spiral magnetic ordering to a conical spin one was observed at 40 K.