Dielectric and superparamagnetic behavior of nanocrystalline CaFe2O4

Abstract

Nanocrystalline CaFe2O4 ferrite sample was synthesized through a sol-gel reaction route and annealed at 100°C. Powder XRD, Raman spectroscopy, SQUID magnetometry and dielectric measurements were performed for the thorough characterization of CaFe2O4. XRD and Raman analysis showed formation of single phase nanocrystalline CaFe2O4 in the fcc symmetry with an average particle size of ~70 (±10) Å. Dielectric parameters of CaFe2O4 swiftly decrease in the low frequency range and remain almost constant at higher frequencies. CaFe2O4 display superparamagnetism at room temperature with a high saturation magnetization of ~27emu/g and the M-H curve is well adjusted with a Langevin function for an average crystallite size of ~60 (±9) Å. M-H curve recorded at 5K showed ferrimagnetic behaviour of CaFe2O4 with a saturation magnetization of 30emu/g, coercivity of 300Oe and 9emu/g remanence. ZFC and IFC modes of magnetization depart each other well above the blocking temperature and the blocking temperature was found to be ~49 K at 1000Oe and ~126 K at 50 Oe.