Phase formation and saturation magnetization of La-Zn-substituted M-type strontium ferrites

The phase formation in the La-Zn-substituted M-type hexagonal ferrite series Sr1-xLaxFe12-yZnyO19 with 0 <= x <= 1 (x = y) and 0 <= x <= 0.5 (x >= y) was investigated. Single-phase ferrite compositions were obtained for x = y < 0.4. The lattice parameters of Sr1-xLaxFe12-yZnyO19 exhibit a linear variation with x, i.e. a(0) slightly increases and c(0) decreases with x. In addition, substituted ferrites with x > y were prepared as single phase materials for x <= 0.5. For those compositions with x > y ferrous ions are formed for charge compensation. The saturation magnetization at T= 4.2 K slightly increases with x to reach a maximum of 110 emu/g for x = y = 0.3. For fixed La-concentrations x (0 <= x <= 0.5) Ms increases with Zn-concentration y up to the ferrite composition at the maximum solid solubility limit ymax.