Moessbauer studies and magnetic studies of Ni doped orthoferrites PrFe_(1-x)Ni_xO_3 (x ≤ 0.3)

摘要

The magnetic properties of polycrystalline PrFe_(1-x)Ni_xO_3 (x ≤ 0.3) system were studied using Mossbauer spectroscopy and magnetization measurements. The Mossbauer spectra exhibit six line spectra which loses its sharpness as the Ni substitution increases within the system. As the Ni concentration in the system increases, the hyperfine field and isomer shift shows decrease, which is vivid from the sluggish nature of the sextets. The small value of quadrupole splitting confirms the octahedral environment of the Fe~+3 ions. The magnetization curves show the reversible behavior and represent the fall in negative molecular field leading to AFM frustration. From these results, we conclude that sagging in the spectra reveals the change from antiferromagnetic state to ferromagnetic state, which can be attributed to mixed state of Fe~(+3) ions i.e. high spin (HS) and low spin (LS) which is a consequence of progressive collapse of Hund's rule due to HS→LS transition. These results confirm the weak ferromagnetic component due to canted-AFM spin arrangement of Fe~(3+) magnetic moments.