Novel Aurivillius Bi4Ti3−2xNbxFexO12 phases with increasing magnetic-cation fraction until percolation: a novel approach for room temperature multiferroism. Issue 36 (19th August 2020)

• Record Type: Journal Article
• Authors: Algueró, Miguel; Pérez-Cerdán, Miguel; del Real, Rafael P.; Ricote, Jesús; Castro, Alicia
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 36(2020)
• Page Start: 12457
• Page End: 12469
• Publication Date: 2020-08-19
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0tc03210g
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Aurivillius oxides with general formula (Bi2 O2 )(A m −1 B m O3 m +1 ) are being extensively investigated for room-temperature multiferroism and magnetoelectric coupling. Abstract : Aurivillius oxides with general formula (Bi2 O2 )(A m −1 B m O3 m +1 ) are being extensively investigated for room-temperature multiferroism and magnetoelectric coupling. The chemical design strategy behind current investigations is the incorporation of magnetically active BiMO3 units (M: Fe 3+, Mn 3+, Co 3+ …) to the pseudoperovskite layer of known ferroelectrics like Bi4 Ti3 O12, increasing m . The percolation of magnetic cations at the B-site sublattice is required for magnetic ordering and thus, phases with m ≥ 5 are searched. Alternatively, one can try to directly substitute magnetic species for Ti 4+ in the perovskite slab, without introducing additional oxygen octahedra. We report here the mechanosynthesis of Aurivillius Bi4 Ti3−2 x Nb x Fe x O12 phases with increasing x values up to 1. A maximum magnetic fraction of 1/3, surpassing the threshold for percolation, was reached. Preliminary structural analysis indicated a continuous solid solution, though hints of structural changes between x = 0.25 and 0.5 were found. Ceramic processing was accomplished by spark plasma sintering of the mechanosynthesized phases, including those with high- x ones with reduced thermal stability. This has enabled us to carry out full electrical characterization and to demonstrate ferroelectricity for all phases up to x = 1. Magnetic measurements were also carried out, and weak ferromagnetism was found for x = 1. Therefore, Bi4 TiNbFeO12 is proposed to be a novel room-temperature multiferroic.