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- Title
Experimental characterization of nanocrystalline niobium-doped nickel-zinc ferrites: occurrence of superparamagnetism.
- Authors
Lakshmi, Ch.; Sridhar, Ch.; Govindraj, G.; Bangarraju, S.; Potukuchi, D.
- Abstract
Structural, morphological, magnetic, and dielectric investigations are carried out in Nb-doped (viz., for x equal to 0.0-0.4 by wt%) nanocrystalline Ni-Zn ferrites synthesized by hydrothermal method. XRD, IR studies infer the growth of nano structures and FeO phase. Nb ions segregate at grain boundaries. Crystallite size ( D) varies from 62 to 18 nm with x. FTIR absorption exhibits split at higher x. Saturation magnetization witnesses an overall decrease with x. Trends of M( x) are explained by nature of dopant, preferential replacement, surface canting ( Y- K angles) and lattice contraction. Variations of coercive field ( H) and D infer single-domain to multi-domain morphological transformation. Occurrence of superparamagnetism (SPM) is predicted for zeroed values of Hand for a critical concentration x equal to 0.321. Enhanced Nb-Fe binding with dopant ( x up to 0.2) results for decrease in dielectric constant $$ \varepsilon^{\prime}_{r} $$ , loss factor tanδ and increase in resistivity ρ. Lowered ac conductivity is attributed to blockade of path by Nb ions in the vicinity of B-sites. Relatively higher ρ (~10 Ω cm) and lower loss (tan δ ~10-10) evinced for 10 kHz. Enhanced core loss is realized with x manifested as lowered H and tan δ to usher their utility in high-frequency applications.
- Subjects
MAGNETIC properties; NANOCRYSTALS; FERRITES; NICKEL; NIOBIUM; PARAMAGNETISM; HYDROTHERMAL synthesis; ELECTRIC properties of nanostructured materials; DOPING agents (Chemistry)
- Publication
Journal of Materials Science, 2016, Vol 51, Issue 18, p8382
- ISSN
0022-2461
- Publication type
Article
- DOI
10.1007/s10853-016-0088-0