Abstract
The crystal structure, magnetic and electrical properties of Bi0.96Pb0.04FeO3 and Bi0.92Pb0.04 RE0.04FeO3 (RE=La, Sm, Dy and Yb) polycrystalline samples were prepared by the flash autocombustion technique. X-ray diffraction (XRD) measurements show that the rare-earth doped compositions crystallized in rhombohedral symmetry of space group R3c. The undoped sample consisted needle shape particles while rare earth substitution preferred platelet like particles as clarified from high resolution transmission electron microscopy (HRTEM). Morphological features were examined using field emission scanning electron microscopy (FESEM). Magnetization measurements showed that Yb3+ samples possessed the highest room temperature saturation magnetization while when Bi3+ ions were substituted by La3+ ions, a smaller MS (0.28 emu/g) was obtained. The coexistence of ferroelectric and magnetic transitions was detected using DSC and χM, indicating the multiferroic characteristics of Bi0.92Pb0.04RE0.04FeO3 crystallites. The Néel temperature shifted upwards with decreasing the ionic radius of rare earth ion. Nice correlation was established between microstructure, morphology and magnetic properties in view of the contribution of magnetocrystalline and shape anisotropy in the magnetic parameters values.
HRTEM micrographs for Bi0.96Pb0.04 FeO3 and Bi0.92Pb0.04Sm0.04FeO3 (The inset: SAED)