Enhancement of magnetic properties in Mn-Zn substituted M-type Sr-hexaferrites

摘要

We report the magnetic properties of Mn-Zn substituted M-type Sr-hexaferrites (SrM), SrFe_(12-2x)Mn_xZn_xO_(19), and compare them with those of non-substituted SrM and La-Zn substituted SrM. The highest saturation magnetization (M_S) of 75.6 emu/g was obtained at a Mn-Zn substitution of x=0.1 (SrFe_(11.8)Mn_(0.1)Zn_(0.1)O_(19)), which is higher than those of the non-substituted SrM and La-Zn substituted SrM by 2.6% and 1.7%, respectively. The enhanced M_S can be attributed to the selective substitution of Zn~(2+) and Mn~(4+) into the down-spin site of Fe~(3+) (4f_1 or 4f_2). Sintered anisotropic magnets fabricated with the optimal Mn-Zn doping level of x=0.1 exhibited a remanent magnetic induction (B_r) over 4300 G and maximum energy product (BH)_(max) of ～4.6 MGOe (36.6 kJ/m~3).