LOW TEMPERATURE COMBUSTION FOR PREPARATION OF BaFe12-2x (Mn, Co)xTixO19 (x=0.0 and 1.5) POWDER MATERIALS

Abstract

This papaer reports our recent works on preparation of Co and Ti substituted Barium Hexaferrite of BaFe12O19 and BaFe9Mn0.75CO0.75Ti1.5O19 compositions. Formation of single phase material was obtained through a sol-gel with ammonium nitrate melt technique followed by heating treatments below 1000 C. This was confirmed by their respective diffraction traces which consistenly showing a BaO.6(Fe2O3) compound though a slightly shift in some diffraction peak position for x > 0 was appreciated. In addition, micrographs of surface for deasified bulk materials showed a homogenous single phase of plate-like hexagonal grains with mean size of 5 - 10 µm. Results of magnetic evaluation by Permeagraph employing a magnetic field up to 2.15 T showed that the hysteresis loop for material with x = 0 was a typical of isotropic Barium Hexaferrite permanent magnet. However, for x = 1.5 the coercivity of magnetic material decreased drastically followed by a slight decrease in "total polarization" due to partial substitution of Fe ions with Mn, Co and Ti ions. A low coercivity with high polarization value combined with a high electrical resistance are properties which are particularly required for absorbtion of electromagnetic wave. It is shown that the low temperature combustion route could be a promising alternative technique for preparation of materials like Barium Hexaferrite based for high frequency application including Radar Absorbing Materials (RAM)