Mossbauer studies and magnetic properties of BaFe12-xAlxO19 grown by a wet chemical process

Polycrystalline BaFe12-xAlxO19 powders (0.0 less than or equal to x less than or equal to 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 Angstrom and c = 23.243 Angstrom for x = 0.0, to a = 5.818 Angstrom and c = 22.754 Angstrom for x = 4.0. The saturation magnetization and the coercivity of BaFe10Al2O19 were 30.2 emu/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 Al3+ occupation of octahedral sites.