Tailoring the ferroelectric and magnetic properties of Bi5Ti3FeO15 ceramics by doping with Co and Y

The ferroelectric and magnetic properties of four-layered Aurivillius Bi5Ti3FeO15 (BFT) compounds via partial substitution of Bi3+ with Y3+ and Fe3+ with Co2+ (according to formula: Bi5-xYxTi3FeO15, x = 0.1, 0.2, 0.3; Bi5Ti3Fe1-yCoyO15, y = 0.1, 0.3, 0.5) were investigated. Polycrystalline ceramics of Co and Y substituted BFT were prepared by conventional solid-state reaction. Crystal structure and phase purity were confirmed via X-ray diffraction and Rietveld refinement. Raman spectral signatures indicate that Y replaces Bi ions in the pseudoperovskite layers and Co replaces Fe ions in the octahedral sites. SEM micrographs show a decrease in grain size for both chemically modified samples when compared to plate-like morphology for unmodified BFT with dimensions ranging from 3 to 5 mu m in length and a thickness of ~0.5 mu m. The decrease in grain size is more pronounced in Co substituted samples with plate-like grain dimensions of 1 mu m in length and 0.2 mu m in thickness. Ferroelectric measurements show unsaturated leaky hysteresis loops in both chemically modified samples until the maximal applied electric field. Magnetic measurements confirm the paramagnetic nature of unmodified and Y substituted BFT ceramics while Co substituted BFT ceramics exhibit a typical ferromagnetic M -H loop. The largest remanent magnetization value of 0.084 emu/g at room temperature is recorded for the Co2+ substituted sample with x = 0.3.

Automated summary

The ferroelectric and magnetic properties of four-layered Aurivillius Bi5Ti3FeO15 (BFT) compounds were investigated by partially substituting Bi3+ with Y3+ and Fe3+ with Co2+. Y3+ replaces Bi ions in the pseudoperovskite layers and Co2+ replaces Fe ions in the octahedral sites. The chemically modified samples show a decrease in grain size, and Co substituted BFT ceramics exhibit ferromagnetic behavior.