Hydrothermal synthesis of uniform Fe-doped Gd(OH)3 nanorods and their magnetic properties: Phase conversion from paramagnetism to ferromagnetism

Abstract High quality pure and Fe-doped Gd(OH)3 nanorods were fabricated through a template-free hydrothermal method for the first time. Analysis of XRD indicates that Fe3+ was incorporating in the interstitial sites rather than occupying the substitutional sites, forming pure hexagonal structure of Gd(OH)3 without any other impurity phase. TEM characterizations show that all the samples perform uniform rod-like morphologies with similar diameter and length, which suggests that the Fe doping has little influence on the morphologies of samples. ICP and XPS spectra suggest that the dopant Fe3+ is incorporated into the inner body sites, not on the surface of nanorods. Magnetic studies show that the magnetic phase can be converted from paramagnetism to room-temperature ferromagnetism by doping Fe3+ ions into the Gd(OH)3 nanorods. The saturation magnetization (Ms) is sensitive to the amount of Fe dopants, and the Ms for Fe0.03Gd0.97(OH)3 nanorods reaches the maximum value of 0.184 emu/g. It is considered that the ferromagnetic ordering is possibly originated from the exchange interaction of Fe3+ through the oxygen vacancies, leading to the formation of point defect-mediated bound magnetic polarons (BMPs). Ruling out the affect of morphologies and secondary magnetic phase on the magnetic properties, the ferromagnetic ordering in uniform Fe-doped Gd(OH)3 nanorods, in which the dopant Fe3+ is incorporated into the inner body sites of nanorods, are of great importance to deeply understand the rare earth-based DMS/DMD systems and have potential applications in spintronic devices.