Abstract
Synthesis, crystal structure, dielectric, and magnetic properties of the Aurivillius phase Bi4−xTbxTi3O12 (x = 0.0, 0.4, 0.6, 0.8) are reported. The samples were synthesized using standard solid state reaction technique. The thermal stability of the obtained solid solutions was investigated. For x ≤ 0.8, the samples crystallized in an orthorhombic symmetry. All the samples showed finite second harmonic generation response indicating a non-centrosymmetric structure. The structural data could be refined using the polar orthorhombic space group B2cb. The orthorhombicity decreases with an increase in the Tb3+ concentration. The orthorhombic distortions in these compositions are related to the Bi3+-based perovskite sublattice. Our results indicate that the non-lone pair Tb3+ cations preferentially occupy the perovskite sublattice initially, but with an increase in the doping concentration they can partially substitute the Bi3+ ions in the fluorite block. Temperature dependent dielectric measurements revealed a decrease in the ferroelectric Curie temperature TC with an increase in x from TC = 904 K (for x = 0) to 877 K (for x = 0.4). Further increase in x led to a cross-over to a relaxor-type behavior. Magnetic measurements showed that the samples are paramagnetic down to 5 K.
Highlights
Multiferroic materials exhibiting dipole and spin orderings simultaneously have attracted a lot of attention during the past decade
The phase purity of the prepared ceramic samples was monitored by X-ray powder diffraction (XRPD) patterns obtained with a D-5000 diffractometer using Cu-Ka radiation
All the XRPD patterns could be indexed in an orthorhombic symmetry
Summary
Multiferroic materials exhibiting dipole and spin orderings simultaneously have attracted a lot of attention during the past decade. Intrinsic multiferroics, where the different ferroic properties occur in one material, are limited in number. Oxides belonging to the Aurivillius family constitute an important class of materials that have been studied since a long time for their ferroelectric [8, 9] and piezoelectric [10, 11] properties. Bi4Ti3O12 (BTO) (where m = 3) has been widely studied for its ferroelectric properties since the early works of Smolenskii et al [12] and Subbarao [13]. The magnetic properties can be enhanced via structural modification using appropriate doping. A lot of work has focused on layered perovskites in general [15], and bismuth layer-structured ferroelectrics in particular [16]. We report on the synthesis and detailed
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