Authors : S. A. Pawade, P. Moharkar,S. Gawali, V. M. Nanoti and K. G. Rewatkar
Page Nos : 352-357
Description :
Abstract :
Al-substituted M-type hexaferrite is a highly anisotropic ferromagnetic material. In the present study, Microwave solgelauto combustion method for synthesis of SrLayFe12-x-yAlxO19powders were explored . It was attempted to prepare aluminum-substituted strontium hexaferrites with compositions Sr La yAlxFe12−x -yO19 having x=0,2,4, 6, and 8. The precursors were prepared by using stoichiometric amounts of Sr, Al and Fe3+ nitrate solutions with urea as the precipitating agent. The hydrothermally prepared precursors were calcined at temperatures in the range of 800–1200 °C.It shows hexagonal magnetoplumbite (M) structure having unit cell dimensions ‘a’ and ‘c’ varies between 5–6 Å and 21–23 Å with same space group P63/mmc (No. 194). The temperature dependent electrical conductivity measurements were carried out at 300–650 K. The compounds are ferromagnetic nature upto Curie temperature and above this show paramagnetic nature. The activation energy has been observed more in paramagnetic region than ferromagnetic region. The temperature dependent magnetic susceptibility measurement has been carried out and from this Curie molar constant has been found to decrease with the increase in Al concentration with respect to Curie temperature. There is no significant variation in lattice parameter with Al concentration. The experimental results have shown that Al3+ ions substitute Fe3+ ions in the sublattice, and the samples remain in the hexagonal magneto plumbite phase. The saturation magnetization Ms and remanence Mrof M-type Sr La yAlxFe12−x -yO19 nano particles linearly decrease when x increases.
Keywords : XRD; hexagonal ferrite; porosity; magnetic susceptibility etc.
