2014 | 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 | 1999 | 1998 | 1997 | 1996 | 1995 | 1994 | 1993 | 1992 | 1991 | 1990 | 1989 | 1988 | 1987 | 1986 | 1985 | 1984 | 1983 | 1982 | 1981 | 1980 | 1979 | 1978 | 1977 | 1976 | 1975 | 1974 | 1973 | 1972 | 1971 | 1970 | 1969 | 1968 | 1967 | 1966 | 1965 | 1964 | 1963 | 1962 | 1961 | 500 | 0
Synthesis and magnetic characterization of mixed CoFe2O4 spinel ferrite: Insights into structural properties, magnetic entropy, and tricritical behavior
Authors: Saidi, L.; Hajji, ABA; Hadded, S.; Benali, A.; Hlil, E.K.; Graça, MPF; Dhahri, E.; Costa, BFO
Ref.: J. Alloys Compd. 1048, 185083 (2025)
Abstract: In the present paper, the Cobalt spinel ferrite nanoparticles (CFO) were successfully synthesized throughout glycine Sol-gel self-ignition method. We validate the presence of a homogeneous cubic mixed-spinel ferrite phase identified by the Fd-3m space group according to a Rietveld analysis of the X-ray diffraction data, with the general formula (Co0.202Fe0.798)[Co0.789Fe1.202]O4. The synthesized CFO material presents an average crystallite size equal to 36.3 nm. Besides, optical measurements including UV-Vis absorption and photoluminescence revealed a broad emission band around 323 nm with an additional shoulder at 398 nm, attributed to the existence of multiple electronic transitions with a direct band gap of 1.95 eV. We additionally performed the analysis of the magnetic entropy, using the Maxwell formalism, while taking magnetic fields up to 3 Tesla into account. It´s maximum value (- Delta SM)max was found to be 1.42 J.Kg-1.K-1, leading to an RCP (relative cooling power) value of about 100 J.Kg-1. These interesting values allow the use of these nanoparticles in the magnetic refrigeration with low applied magnetic fields. Furthermore, we analyzed the critical parameters beta, gamma, and S using the Modified Arrott Plots (MAP) and the Kouvel-Fisher (KF) plots which were found to be respectively equal to 0.259, 1.029, and 4.887. These outcomes demonstrate how well the Tricritical-mean field model describes the long-range interactions in the CFO nanoparticles under investigation, which was confirmed as well from the exchange distance J(r) = r-4.624.
