Phase evolution and magnetoelectric coupling studies in multiferroic Fe doped BST solid solutions

Polycrystalline Ba0.96Sr0.04Ti1-3x/4FexO3 samples (0.06 ≤ x ≤ 0.15) were prepared using solid state reaction technique. The Rietveld refined XRD data confirmed the phase purity and tetragonal crystal structure up to x = 0.08. An additional hexagonal Fe doped BaSrTiO3 phase along with small amount of segregated Fe2O3 was also detected in x ≥ 0.08 samples. The average grain size as measured using FESEM was observed to be ≈ 0.67 μm. The presence of both Fe2+/ Fe3+ ions in all the samples and a decreasing Fe3+ concentration with x was confirmed using XPS analysis. The remnant polarization value was found to decrease with increasing Fe concentration. The magnetization data reveal that all the samples exhibit magnetic ordering with x = 0.08 sample exhibiting best magnetic parameters. The M-E coupling strength ≈10.05 and 9.62% has been observed in x = 0.08 and x = 0.10 samples. The conductivity vs frequency measurements (at different temperatures) reveal that the samples conduct via correlated barrier hopping of electrons trapped at the singly charged oxygen vacancy sites.