Aging Effects on the Structural and Magnetic Properties of Terbium–Aluminium Co-doping of Yttrium Iron Garnet Films Prepared Using the Sol–Gel Method

Abstract

The terbium–aluminium co-doped yttrium iron garnet (Tb0.2Y2.8Al1Fe4O12) nanoparticles films, prepared via a sol–gel method, were aged variously for 2 days, 3 days, 4 days and 5 days. The films were deposited on quartz substrates using a spin coating technique then annealed at 900°C in air for 2 h. The microstructural and magnetic properties of the films were measured using an x-ray diffractometer (XRD), a field emission scanning electron microscope and a vibrating sample magnetometer. The XRD results showed that all the resultant films were a single phase regardless of aging time. A change in the lattice parameter’s behavior was observed at the longer aging times. At an aging time of 5 days, the films became highly agglomerated and exhibited the greatest thickness value of 458.9 nm. The saturation magnetization, Ms, of the films decreased from 31 kA/m to 6 kA/m as the aging time was increased from 2 days to 5 days, due to the increasing Fe–O bond length resulting from larger grain sizes. The increase in aging time to 5 days caused a reduction in the coercivity, Hc, of films due to the multi-domain formation.