Quest for Lead Free Relaxors in YIn1–xFexO3 (0.0 ≤ x ≤ 1.0) System: Role of Synthesis and Structure

The B-site tailored YIn1–xFexO3 (0.0≤ x≤ 1.0) series was synthesized by glycine-aided gel-combustion technique and subjected to extensive structural and electrical investigations. The temperature had tremendous bearing on the phase evolution exhibited by the system. The entire system crystallized as C-type metastable polymorph in the as–synthesized form. Hexagonal polymorphs of Fe3+-rich compositions could be isolated by controlled heat treatment at 750 °C. Raman spectroscopic investigations showed that, while there is a general shrinkage of the lattice due to substitution of a smaller ion at In3+-site, there is an apparent dilation of the Y–O bond, and this anomaly reflects in the electrical behavior exhibited by the system. The single-phasic hexagonal nominal compositions, YIn1–xFexO3 (0.0 ≤ x ≤ 0.3), were also studied by impedance spectroscopy. The dielectric constant was found to drastically increase from 10 for YInO3 to 1000 for YIn0.7Fe0.3O3 at room temperature stressing the role of B-site tailoring...