Structural evolution and multiferroic properties in the vicinity of MPB of Ca2Bi4Ti5-xMnxO18 solid solutions

• Published in: Journal of magnetism and magnetic materials 2020-03, Vol.498, p.166209, Article 166209
• Main Authors: Li, Y., Zhou, S.D., Wu, H., Chen, J.K., Wang, Y.G., Pan, F.M.
• Format: Article
• Language: English
• Subjects: Ceramics; Crystal structure; Dielectric properties; Grain size; Grain size distribution; Magnetic properties; Magnetoelectric; Manganese; Materials substitution; Molten salts; Morphotropic phase boundary; Multiferroic; Multiferroic materials; Octahedrons; Perovskites; Phase transition; Raman spectra; Room temperature; Solid solutions; Vibration mode
• ISSN: 0304-8853; 1873-4766
• DOI: 10.1016/j.jmmm.2019.166209

•A morphotropic phase is successfully constructed in the Ca2Bi4Ti5-xMnxO18 compound.•The magnetoelectric coupling coefficient of 12.3 mV/(cm·Oe) is detected at x = 1.5.•The distorted MnO6 octahedron affects the changes of magnetization prominently. The crystal structure transition and its effect on the multiferroic characteristics were investigated in Ca2Bi4Ti5-xMnxO18 (0 ≤ x ≤ 2) ceramics synthesized by the molten salt method. Mn substitution induces variations in a/b ratio and the distortion degree of oxygen octahedrons, which can effectively regulate the multiferroic properties at room temperature. The structure changes from orthorhombic B2cb to tetragonal I4/mmm with a morphotropic phase region forming in the ceramic at x = 1.5. The Raman spectra manifest that Mn substitution not only alters the vibration mode of MnO6 octahedron but also changes the structural environment of TiO6 in the perovskite lattice. The average grain size increases gradually and the grain size distribution gets homogeneous with the increase in Mn content. All the ceramics show a lossy dielectric behavior. The addition of Mn results in a significant enhancement in macroscopic magnetization and dielectric properties. In addition to this, the magnetoelectric coupling effect has also been improved and a maximum magnetoelectric coefficient of α ≈ 12.3 mV/(cm·Oe) is attained for the ceramic sample with x = 1.5.