Synthesis and tailoring the structural and magnetic characteristics of Zn-Zr substituted Sr-hexaferrite targeting diverse applications

SrZnxZrxFe12-2xO19 (x varying within 0.1-0.4) samples were prepared successfully via solid state route. Their structural characteristics (along with microstructural and magnetic) have been discussed. Rietveld refinement established the phase purity for the samples x <= 0.3 (goodness-of-fit <1.15) whereas the presence of ZnFe2O4 and SrZrO3 impure phases was observed in x = 0.4 sample. The three-phase model resulted in decreasing chi(2) values from 1.21 to 1.05 for x = 0.4 sample. The XRD findings also reveal an increasing cell volume from 690.675 angstrom(3) (x = 0.1) to 693.096 angstrom(3) (x = 0.3) and a decreasing porosity from 33% to 30% on increasing 'x'. The average grain size increases from 0.83 mu m to 1.04 mu m according to FESEM micrographs with increasing 'x'. The TEM measurements reveal the presence of rod like particles (in addition to random shaped particles) in x = 0.1-0.3 samples. M v/s H studies reveal, and increase in Ms from 90.26 emu/g (for x = 0.0) to 91.41 emu/g (for x = 0.1) and a decreasing trend afterwards to 87.90 emu/g (at x = 0.3). H-c value continuously decreases from 5032 Oe (for x = 0.0) to 1903 Oe (for x = 0.4). Low temperature M H and M-T measurements coupled with room temperature M H measurements reveal the absence of superparamagnetic behaviour. The magnetic data suggest that all the samples possess hard ferrite characteristics and could be useful for microwave absorbers, permanent magnets as well as high-density recording media applications.