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

Abstract

SrFe 12 O 19 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 Zn 2+ -Zr 4+ co-dopant on magnetic and structural properties of SrZn x Zr x Fe 12-2x O 19 (x = 0.00-1.00) samples calcined between 900-1100°C was investigated. XRD data shows that the cell volume increases (from 690.45Å 3 (x = 0.00) to 705.72Å 3 (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 ZnFe 2 O 4 (≈2.25) & SrZrO 3 (≈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 Zn 2+ -Zr 4+ 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 Zn 2+ -Zr 4+ concentration. A maximum M s value ≈ 70.89 emu/g was observed in x = 0.20 sample at 1100°C. M s value also decreases for x > 0.20 at each calcination temperature.

Structural and Magnetic Characterization of Ni-Co Mixed Ferrite Nanopowders Synthesized via Coprecipitation and Sol-Gel Methods

“…In several investigations that have studied the effect of heat treatment temperature on the crystal structure, size, and physical properties of nanoparticles, it has been reported that the crystallinity of nanometric particles synthesized using methods such as coprecipitation or sol-gel improves as the heat treatment temperature increases 36,37 . Generally, as-synthesized nanoparticles have been found to exhibit low crystallinity 38,39 . To obtain pure Ni-Co mixed ferrite nanocrystals, the powders synthesized using both methods were calcined at 600 °C for 2 hours in an air atmosphere.…”

Influence of High Temperature on the Crystal Structure of SrFe12O19 Nanoparticle

“…Nanoparticles annealed at 1,000°C possess a uniform hexagonal shape with narrower particle size distribution hence narrow size distribution leads to lower porosity [55]. When particles are annealed at 1,300°C the nanoparticles illustrate an increase in the average grain sizes with calcination temperature due to the fusion of smaller grains into larger grains [56][57][58]. Particle size distribution was shown in Figure 3 for nanoparticles annealed at 1,000 and 1,300°C.…”

The Impact of Al3+ ion substitution on microwave absorption of hexaferrite compound Ba0.6Sr0.4Fe12−xAlxO19 (x = 0.25, 0.50, 0.75, and 1.00)

“…A material must have a high reflection loss (RL) and a broad frequency range in order to be used as a microwave absorber. Attenuation of microwaves is affected by the magnetic loss [4], material coercivity [5,6], and dielectric loss [7].…”