Tailoring the magnetic properties of M-type strontium ferrite with synergistic effect of co-substitution and calcinations temperature

Abstract

SrFe12O19 samples were initially prepared using sol-gel auto-combustion method and calcined from 500 to 1100°C (for 6 h). XRD data established the phase formation temperature of SrM phase to be ≈1000°C. Thereafter, the effect of Zn2+-Zr4+ co-dopant on magnetic and structural properties of SrZnxZrxFe12-2xO19 (x = 0.00–1.00) samples calcined between 900–1100°C was investigated. XRD data shows that the cell volume increases (from 690.45Å3 (x = 0.00) to 705.72Å3 (x = 1.00)) while crystallite size decreases (from 123.9 nm (x = 0.00) to 62.3nm (x = 1.00)) calcined at 1000°C. The Rietveld refinement of XRD data confirms a) x = 0.00 sample to be phase pure and b) the presence of ZnFe2O4 (≈2.25) & SrZrO3 (≈2.93%) impurity phases in x = 1.00 sample, calcined at 1000°C. FESEM micrographs revealed that a) grain size decreases for x > 0.20 with `x’ at 900°C and b) increases from 122 nm at 900°C to 443 nm at 1100°C, for x = 0.00. Broadening of Raman bands reveals generation of strain in the lattice with enhancement of Zn2+-Zr4+ concentration. The magnetic studies reveal that the coercivity monotonically decreases (from 5358(x = 0.00) Oe to 690(x = 1.00) Oe at 1000°C) with enhancement of Zn2+-Zr4+ concentration. A maximum Ms value ≈ 70.89 emu/g was observed in x = 0.20 sample at 1100°C. Ms value also decreases for x > 0.20 at each calcination temperature.

Keywords

• calcination temperature
• crystal straining
• emi shielding
• magnetic recording
• saturation magnetization