A probe into the structural, magnetic and dielectric properties of barium and lithium substituted pseudobrookites

Abstract

Pure pseudobrookite Fe₂TiO₅ and its lithium and barium substituted varieties namely, Ba_2y Fe_2−x Li_3x Ti_1−y O₅ and Ba_3x/2 Fe_2−x Li_4y Ti_1−y O₅ (x = y = 0.05) are synthesized by solid-state reaction method. Pure and lithium and barium doped samples of pseudobrookites show the single phase orthorhombic structure. Substitution has reduced the particle (crystallite) size but enhanced the grain size. A new intense plane (122) is observed in the substituted samples indicating that Barium has entered this plane. Lithium intercalation is also observed. Dielectric studies have confirmed the Maxwell-Wagner interfacial polarization and the space charge is seen to have almost doubled with doping. The hysteresis loops are recorded and the variation of normalised susceptibility with absolute temperature is observed. An asymmetric shift and constriction of loops is observed. Presence of barium and lithium has also brought about a long magnetic range ordering in pseudobrookites. Susceptibility measurements show that the Curie temperature in the barium-rich sample approaches room temperature and can be a potential switch material.