Antiferromagnetic ordering in lithium deintercalated Fe1−xZnxPO4: A Mössbauer spectroscopy study

Abstract

Abstract Various compositions of Fe1−xZnxPO4 (x = 0.1, 0.2, 0.3, and 0.5) were synthesized by solid-state reaction and chemical lithium deintercalation processes, and their magnetic properties were characterized based on Mossbauer analysis. The synthesized Fe1−xZnxPO4 have orthorhombic structures with space group Pnma. The magnetization curves of Fe1−xZnxPO4 show the antiferromagnetic behaviors and magnetic phase transition caused by the strong crystal field in the FeO6 octahedral sites. The Neel temperature (TN) of Fe1−xZnxPO4 for x = 0.1, 0.2, 0.3, and 0.5 was found to be 97, 82, 63, and 62 K, respectively. Mossbauer spectra below TN appeared to have eight Lorentzian lines with antiferromagnetic ordering. The charge state of Fe ions is the high spin state of Fe3+, as characterized by an isomer shift (δ = 0.28–0.43 mm/s). The value of magnetic hyperfine field (Hhf) decreased with increasing Zn concentration because the superexchange interaction via Fe–O–Zn link is weaker than that via Fe–O–Fe link. Also, the value of electric quadrupole splitting (ΔEQ) gradually decreased with increasing Zn concentration due to the substitution of a Zn ion for the Fe ion, inducing a change in the charge asymmetry at the FeO6 sites. The Debye temperatures are found to decrease with increasing Zn concentration.