Low temperature Mössbauer and DC magnetization studies in nano-sized Ni substituted Co–Zn ferrites

Abstract

Studies in the series of nano ferrites pertaining to the stoichiometry Ni x Co 0.5−x Zn 0.5 Fe 2 O 4 , (0≤ x ≤0.5) show that contrary to the trend in bulk Co-Zn and Ni-Zn ferrites, the observed saturation magnetization of Ni-Zn ferrite (x = 0.5) is larger than Co-Zn ferrite (x = 0) and are due to finite size effects. This is evident from calculations which show that the magnetic particle sizes are 1.6 nm for Co-Zn ferrite and 2.4 nm for Ni-Zn whereas their average crystallite sizes are 5 to 3 nm respectively. Low temperature Mössbauer spectroscopic studies show that this can be attributed to an increase in an ordered core with the increase in Ni content which is reflected as a corresponding increase in the saturation magnetization.

Anisotropy and domain state dependent enhancement of single domain ferrimagnetism in cobalt substituted Ni–Zn ferrites

“…The splitting of octahedral site into B and B 1 is the most often observed in ferrites at the nanoparticle scale and can be attributed to random cation distribution at A-site. [39][40][41][42][43][44] In order to estimate the probable cation distribution, various parameters included in Table 3 were considered. 45 The cubic structure is maintained with almost zero quadrupole splitting values and within the limits of experimental error.…”