Effects of Sn4+ doping and oxygen vacancy on magnetic and electrical properties of yttrium iron garnet prepared by sol-gel method

Abstract Sn-substituted yttrium iron garnet samples, Y3Fe5-xSnxO12 (x = 0–0.1, step 0.02) were prepared using a citrate sol–gel method and followed by a sintering process. Synchrotron X-ray diffraction (SXRD), X-ray absorption near edge structure (XANES), scanning electron microscope (SEM) and Fourier infrared spectroscopy (FTIR) measurements were used to investigate the structure parameters, valence state of Fe, oxygen vacancies and lattice distortion in the samples. The magnetic properties of the samples were measured with the SQUID and VSM equipments. The Sn substitution and oxygen vacancies cause the transformation of Fe3+ to Fe2+ which leads to the decrease of Curie temperature and slight increase of saturation magnetization. Temperature dependence of the resistivity in the range of 300–573 K was investigated to elucidate the conduction mechanism in the samples. The resistivity of the sol-gel derived samples was found to be nine orders of magnitudes lower than the value for the bulk sample prepared by flux-grown method. The effects of Fe2+ centers, lattice dislocation, porosity and grain boundary on the resistivity are discussed. This study indicates that Sn-substituted yttrium iron garnets are good candidates for sensor elements which operate based on electrical signals.