Multiferroic Aurivillius Bi4Ti2−xMnxFe0.5Nb0.5O12 (n = 3) compounds with tailored magnetic interactions. Issue 46 (15th November 2021)

• Record Type: Journal Article
• Authors: Algueró, Miguel; Sanz-Mateo, Jorge; del Real, Rafael P.; Ricote, Jesús; Fernández-Posada, Carmen M.; Castro, Alicia
• Is Part Of: Dalton transactions. Volume 50:Issue 46(2021)
• Page Start: 17062
• Page End: 17074
• Publication Date: 2021-11-15
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt02220b
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A new series of three-layer Aurivillius oxides containing Fe 3+ and Mn 4+, argued to be too small for its introduction into the crystal structure, is presented. This is a novel family of multiferroic layered oxides with tailored magnetic interactions. Abstract : Aurivillius compounds with the general formula (Bi2 O2 )(A n −1 B n O3 n +1 ) are a highly topical family of functional layered oxides currently under investigation for room-temperature multiferroism. A chemical design strategy is the incorporation of magnetically active BiMO3 units (M: Fe 3+, Mn 3+, Co 3+ …) into the pseudo-perovskite layer of known ferroelectrics like Bi4 Ti3 O12, introducing additional oxygen octahedra. Alternatively, one can try to directly substitute magnetic species for Ti 4+ in the perovskite slab. Previous reports explored the introduction of the M 3+ species, which required the simultaneous incorporation of a 5+ cation, as for the Bi4 Ti3−2 x Nb x Fe x O12 system. A larger magnetic fraction might be attained if Ti 4+ is substituted with Mn 4+, though it has been argued that the small ionic radius prevents its incorporation into the pseudo-perovskite layer. We report here the mechanosynthesis of Aurivillius Bi4 Ti2− x Mn x Nb0.5 Fe0.5 O12 ( n = 3) compounds with increasing Mn 4+ content up to x = 0.5, which corresponds to a magnetic fraction of 1/3 at the B-site surpassing the threshold for percolation, and equal amounts of Mn 4+ and Fe 3+ . The appearance of ferromagnetic superexchange interactions and magnetic ordering was anticipated and is shown for phases with x ≥ 0.3. Ceramic processing was accomplished by spark plasma sintering, which enabled electrical measurements that demonstrated ferroelectricity for all Mn 4+ -containing Aurivillius compounds. This is a new family of layered oxides and a promising alternative single-phase approach for multiferroism.