Observation of multiferroic character with the correlation of dielectric and optical study in Ho3+ substituted Bi4Ti2FeO12 Aurivillius ceramic.

Ho–substituted Bi_4-xHo_xTi₂FeO₁₂ (x = 0, 0.5, 1.0, 1.5) n = 3 Aurivillius layered perovskite compounds were prepared by a conventional solid-state reaction method. X-ray diffraction study reveals that the compounds exhibited a major orthorhombic structure with the B2cb space group. A plate-like grain with high randomness in the distribution of Ho-modified BTFO compounds was noticed in the SEM studies. T—dependent dielectric studies were performed to examine the role of defect dipole orientation and oxygen vacancies on dielectric relaxation. For x > 0.50 compositions, a decrease in Curie temperature (T_m) with the increase in Ho-substituted in BTFO ceramics was observed. A temperature-dependent AC conductivity study reveals that the ionic conductivity induced by doubly ionized oxygen vacancies is prominent in the high-temperature region. An Increase in polarization values was observed with Ho doping due to improved grain boundaries. The detailed studies on the ferroelectric (P-E) loops and magnetization (M-H) loops of Ho—substituted BTFO ceramics were determined to point out the inherent multiferroic character. The basic photoluminescence (PL) studies indicated a well noticed two distinct bands in the visible region along with a weak PL band observed in the infra-red (IR) region, which suggests the emission involves the two types of Ho³⁺ centers for the visible bands. [ABSTRACT FROM AUTHOR]