Superparamagnetic Behavior of Zn and Al Substituted Cobalt Nanoferrites

• Published in: Journal of superconductivity and novel magnetism 2019-09, Vol.32 (9), p.2793-2797
• Main Authors: Msomi, J. Z., Masuku, S. J., Nhlapo, T. A., Moyo, T., Strydom, A. M., Britz, D., Jili, T. P.
• Format: Article
• Language: English
• Subjects: ALUMINIUM ADDITIONS; CHANNELING; Characterization and Evaluation of Materials; COBALT COMPOUNDS; COMPARATIVE EVALUATIONS; Condensed Matter Physics; DOPED MATERIALS; FERRITES; IRON 57; Magnetic Materials; Magnetism; MAGNETIZATION; MOESSBAUER SPECTROMETERS; NANOPARTICLES; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; Original Paper; PARAMAGNETISM; Physics; Physics and Astronomy; SPECTRA; Strongly Correlated Systems; Superconductivity; SUPERPARAMAGNETISM; X-RAY DIFFRACTION; ZINC ADDITIONS
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-019-5036-1

Nanostructured Zn- and Al-doped cobalt spinel ferrites Zn x Co 1- x Fe 2- x Al x O 4 (0 ≤  x  ≤ 1.0) with particle size in the range of 7–13 nm were synthesized by glycol-thermal reaction. XRD analysis confirmed single-phase cubic spinel structure with no impurity phases. The Mössbauer spectra for Zn- and Al-substituted fine powders could be resolved into two quadrupole doublets associated with 57 Fe nuclei in paramagnetic spin phase. An unusual reducing magnetization with increasing particle size has been observed. The field cooled and zero field cooled magnetization measurements show superparamagnetic nanoparticles in the compounds investigated. The blocking temperatures ( T B ) are sensitive to particle size. Larger particles are blocked at higher temperatures compared to smaller particles at the same field.