Effects of Al Substitution on Dielectric Response and Magnetic Behavior of Yttrium Iron Garnet Ceramics

Structure, dielectric response, and magnetic properties of Y 3 Fe 5− x Al x O 12 ( x = 0, 0.5, 1, 2, and 3) ceramics were investigated. X‐ray diffraction ( XRD ) patterns indicate a single phase with garnet structure in space group Ia3d for all sintered samples. Rietveld refinement of XRD data suggest that Al 3+ substitutes for Fe 3+ at tetrahedral sites. All the samples show a giant dielectric response which originates from the charge carrier hopping between the Fe 2+ and Fe 3+ . The activation energy of the hopping process increases with increasing Al substitution. The a‐d super‐exchange interaction becomes weak as the content of Al increases, which results in the decrease of saturation magnetizations and magnetic ordering temperatures.