Analysis Of Barium Hexaferrites

Introduction

The M-type hard ferrites have hexagonal crystal structure. The formula of hard ferrites can be generally represented as (MeO.6Fe2O3), where Me is divalent metal such as Sr, Ba, and Pb or a mixture of these [12]. Barium hexaferrites (BaFe12O19) with a magnetoplumbite structure are well known as hard magnetic materials which are based on iron oxides. Hexagonal ferrites are referred to as hard because the direction of magnetization cannot be changed easily to another axis [].Barium ferrite possesses relatively high Curie temperature, coercive force and magnetic anisotropy field, as well as its excellent chemical stability and corrosion resistivity [].The magnetic and dielectric characteristics of hexagonal ferrites strongly depend

The weight ratio of balls to milled material was 5:1. The mechanically alloyed powders were cold pressed into pellets with a diameter of 12 mm. Cold pressed samples were annealed for 1 h at the temperatures of 800 ◦C, 900 ◦C, 1150 ◦C under air. The crystalline phase formation of barium hexaferrite, magnetite and composites powder was further investigated with X-ray diffraction (XRD) spectra using an X-Pert PANalytical diffractometer (PW3050/60) using CuKα radiation in the range 20° to 80°, the magnetization vs magnetic field (M-H) plot of barium hexaferrite was obtained using a vibrating sample magnetometer (VSM) and the average particle size was obtained from the scanning transmission electron microscope (STEM). The Room temperature

X-ray Photoelectron spectroscopy (XPS) studied by (S/N: 10001,

Prevac, Poland) spectra were taken with AlKα (hν¼51,486.6 eV) radiation and a hemispherical energy analyzer. The Rietveld analysis was performed applying DBWS-9807 program that is an update version for Rietveld refinement with PC and mainframe computers.

Results and discussion

Figure 1 shows the XRD patterns of the BaCO3

Fig. 2b shows the deconvolution of Fe spectrum done using origin-8.5 software considering Gaussian function. The fitted peaks at 711.2 eV and at 713.6 eV of main 2p3/2 peak, corresponds to Fe2þ and Fe3þ oxidation state [28]. The satellite peak (718.8 eV) and 2p1/2 peak at 725.4 eV are indicating the presence of Fe3þ

[29,30]. The electronic state of Fe present in BaFe12O19 was determined through X-ray photoelectron spectroscopy. The survey spectrum

(Fig. 3(a)) indicates the presence of Ba, Fe and O peaks. The C 1s peak (284.5 eV) was used as the reference for charge correction.

Fig. 3(b) shows the deconvolution of Fe spectrum done using CASA

XPS software with a mixture of Gaussian and Lorentzian function and Shirley function for background. The 2p3/2 peak at 710.5 eV corresponds to Fe2O3 (Fe3þ) [19] and the satellite peak (718.8 eV) is 8.2 eV from the main 2p3/2 peak (710.5 eV), indicating the presence of Fe3þ. Moreover, the peak at 714.1 eV corresponds to surface peak [20], which can be attributed to the reduction in coordination of Fe (i.e. in hexaferrite, Fe is present in five nonequivalent crystallographic sites, three octahedral, one tetrahedral and one site surrounded by five oxygen atoms forming a