Structural, Magnetic Evaluation of Neodymium Doped Nickel-Zinc-Iron Soft Spinel Metal Oxides for Humidity Sensor Applications

A series of combustion assisted low-temperature neodymium substituted Ni–Zn–Fe (NZF) nanoparticles were synthesized to unravel the impact on functional behavior of NZF due to the presence of larger Nd ions. The nanopowders were structurally evaluated with X-ray diffraction and infrared spectroscopy measurements without further heat treatment. X-ray diffraction clearly evident the monophasic nature of all the samples and solubility of Nd ions in the spinel unit cell. The average crystallite size from Scherrer and Williamson–Hall method are found below 30 and 20 nm for all the samples, respectively. A distinct shift was observed in most intense peak (3 1 1) suggesting the adjustment among interionic distances to accommodate larger ions. The microstructure, morphology was evaluated from SEM measurements. Magnetic measurements at room temperature show a dramatic change in magnetization, improvement in soft-magnetic nature with low coercivity behavior with Nd substitution. The variation of resistance with respect to humidity conditions suggested that these materials are potentially suitable for resistive humidity sensor applications.