Mossbauer studies and magnetic properties of BaFe/sub 12-X/Al/sub X/O/sub 19/ grown by a wet chemical process

Polycrystalline BaFe/sub 12-x/Al/sub x/O/sub 19/ powders (0.0/spl les/x/spl les/4.0) were fabricated by a wet chemical process. Magnetic properties and crystalline structure were investigated by using an X-ray diffractometer, vibrating sample magnetometer, and Mossbauer spectroscopy. The result of X-ray diffraction patterns shows that the a and c lattice parameters were decreased with increasing x from a=5.901 /spl Aring/ and c = 23.243 /spl Aring/ for x = 0.0, to a = 5.818 /spl Aring/ and c = 22.754 /spl Aring/ for x = 4.0. The saturation magnetization and the coercivity of BaFe/sub 10/Al/sub 2/O/sub 19/ were 30.2emu/g, 8.7 kOe, respectively, at room temperature under an applied field of 15 kOe. With increasing x, the relative intensity of octahedral sites has been obviously decreased. The authors interpreted the decreasing of relative area ratio of octahedral sites in Mossbauer spectra as closely related to the Al/sup 3+/ occupation of octahedral sites.