The Phase Transformation and Crystal Structure Studies of Strontium Substituted Barium Monoferrite

Unlike other AFe₂O₄ ferrite materials, Barium Monoferrite (BaFe₂O₄) have an orthorhombic structure which is very interesting to further study the crystal structure and phase formation. In this study, Strontium substituted Barium Monoferrite in the form of Ba_(1-x)Sr_(x)Fe₂O₄ has successfully been synthesized through solid state reaction method which includes BaCO₃, SrCO₃, and Fe₂O₃ as starting materials. Ba_(1-x)Sr_(x)Fe₂O₄ was made by varying the dopant composition of Strontium (Sr²⁺) from x = 0, 0.1, 0.3, and 0.5. Each composition was assisted by ethanol and continued to the milling process for 5 hours then followed by sintering process at 900 °C for 5 hours. The phase transformation was studied by using X-ray diffractometer (XRD) and Rietveld refinement using General Structure Analysis System (GSAS) also 3D crystal visualization using VESTA. Referring to the refinement results, a single phase of BaFe₂O₄ was formed in x = 0 and 0.1. The composition has orthorhombic structure, space group B b21m, and lattice parameters of a = 19.0229, b = 5.3814 c = 8.4524 Å, α = β = γ = 90° and a = 18.9978, b = 5.3802 c = 8.4385 Å, α = β = γ = 90° respectively. In the composition of x = 0.3 it was found that the phase of BaSrFe₄O₈ begin to form due to the overload expansion of the Sr²⁺ occupancy which made the distortion of the initial lattice parameters and finally in the x = 0.5 composition the single phase of BaSrFe₄O₈ was clearly formed. Energy Dispersive Spectroscopy (EDS) was used to confirm the change of the material structure by measuring the elemental compound composition ratio. The result of EDS spectra clearly exhibited the dominant elements were Barium (Ba), Strontium (Sr), Iron (Fe), and Oxygen (O) with the compound ratio (Atomic percentage and mass percentage) correspond to the BaFe₂O₄ and BaSrFe₄O₈ phase.