Structural, Magnetic, and Thermodynamic Evolutions of Zn-Doped Fe₃O₄ Nanoparticles Synthesized Using a One-Step Solvothermal Method

Abstract

Zn-doped Fe 3 O 4 magnetic nanoparticles represented as Zn x Fe 3- x O 4 with different Zn contents of x varying from 0.0 to 1.0 were synthesized using a facile one-step solvothermal method. The Zn/Fe ratio in these particles could be accurately controlled using this facile synthesis technique. The ICP-OES and XRD measurements indicated that in the x range from 0 to 0.4 the doped Zn 2+ may replace the Fe 3+ at the A site and consequently the B-site Fe 2+ changed to Fe 3+, while above 0.4 the Zn 2+ tends to replace the B-site Fe 2+ . The morphologies and size distributions of these samples characterized from the TEM showed that the nanoparticles appeared to aggregate into magnetic nanocrystal clusters with varying cluster sizes and different Zn doping contents. The magnetic measurement and Mössbauer spectra investigation revealed that the magnetic properties of the Zn x Fe 3- x O 4 would exhibit a sensitive dependence with the doped Zn variations. Most importantly, the heat capacity studies illuminated that, at low temperatures, the samples could have a ferromagnetic contribution with x = 0.0 and 0.2 and turn to an antiferromagnetic contribution with x = 0.5, 0.8, and 1.0.