Inorganic Chemistry, Vol.53, No.19, 10101-10111, 2014
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 degrees 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 on electrical behavior. More interestingly, careful substitution of Fe into YInO3 could tune the electrical behavior from a dielectric to relaxor ferroelectric in the temperature range studied. The nominal composition YIn0.7Fe0.3O3 showed a classical relaxor ferroelectric like behavior which is an important observation in context of the search for new lead free relaxor materials.