Enhancement of hard magnetic properties of BaFe12O19 nanoparticles

Barium hexaferrite nano particles are prepared through glycine assisted sol-gel auto combustion method with a minimal glycine to nitrate ratio and the pH values of 4, 6 and 9. X-ray diffraction patterns reveal the formation of hexagonal magneto-plumbite structure of BaFe12O19 with a weak intensity of secondary phase in the case of pH 4 and pH 6 samples. Interestingly disappearance of secondary phase at pH 9 sample is noticeable feature. Scanning electron microscope micrographs of the samples show the formation of characteristic hexagonal shape of barium hexaferrite. Constituent elements and chemical composition are analyzed using energy dispersive X-ray spectrum. Fourier Transform Infra Red and Raman spectra show the different metal-oxygen stretching vibration modes corresponding to octahedral, tetrahedral and trigonal bipyramidal sites of BaFe12O19. Magnetization studies show increase in saturation magnetization, squareness ratio, coercivity values on increasing the pH of the solution. 10 % enhancement of Curie temperature is observed (T-c = 495 A degrees C of pH 9 sample) in comparison to its bulk counterpart T-c = 450 A degrees C reported earlier. Enhancement of magnetic properties is achieved by optimizing pH and suitable choice of post annealing temperature during synthesis of nanoparticles of barium hexaferrite.