Structural, magnetic properties, and hyperfine interactions of Ni0.8Cu0.1Zn0.1MoxFe2-2xO4 (0.0 ? x ? 0.1) nanospinel ferrites

Abstract

Ni0.8Cu0.1Zn0.1MoxFe2-2xO4 (x <= 0.1) nanospinel ferrites (Mo -> NiCuZn NSFs) were produced by sol-gel approach. A spinel structure formation with no impurities was confirmed by X-ray diffraction (XRD) patterns. The nanoparticles' morphology and chemical composition of the products have been confirmed via SEM, TEM, HR-TEM, and EDX. By fitting Mossbauer spectra at RT, Hyperfine parameters were determined. A superparamagnetic state was observed in all samples. The Mo4+ were found to reside in the B site mainly. Isomer shift values showed that Mossbauer spectra composed magnetic Fe3+ sextets. Magnetic characteristics of Mo -> NiCuZn NSFs are probed employing hysteresis loops at 300 K and 10 K. The significant role of Mo ions in the magnetic characteristics of the host material is revealed by employing saturation magnetization (M-s), magnetic moment (n(B)), coercivity (H-c), SQR (squareness ratio), and magneto-crystalline anisotropy constant. While the samples show a superparamagnetic behavior at 300 K, they represent a magnetically soft material at 10 K. The magnetic parameters, with a minimum magnetization at x = 0.06, fluctuate with respect to Mo concentration at each temperature. The Ms and nB become the maximum for the Mo -> NiCuZn NSFs (x = 0.02) which yields the minimum H-c. The SQR is negligible at 300 K and low (much less than 0.5) at 10 K, reflecting the generation of multi-magnetic domains and a relatively low anisotropy field.