Structural phase separation and optical and magnetic properties of BaTi_(1-x)Mn_(x)O_(3) multiferroics

摘要

Our work studies the influences of the Mn doping on structural characterization and optical and magnetic properties of BaTi_(1-x)Mn_(x)O_(3) (x velence 0.0-0.12) prepared by conventional solid-state reaction. Detailed analyses of XRD patterns and Raman scattering spectra indicate an incorporation of Mn dopants into the Ti sites of BaTiO_(3) host lattices, and the tetragonal-hexagonal transformation taking place at a threshold concentration of x_(c) approx= 0.01. An increase of Mn-doping content in BaTi_(1-x)Mn_(x)O_(3) introduces more electronic levels associated with lattice defects and Mn ions to the forbidden gap and thus reduces luminescent intensity in the visible region. Magnetic data recorded at room temperature reveal that all the samples exhibit ferromagnetic order, and there is a phase separation in magnetism as varying x values. Particularly, the samples with x(velence)0.5-0.7 have a coexistence of two ferromagnetic phases with different coercivities, which are associated with tetragonal and hexagonal Mn-doped BaTiO_(3) structures. The nature of ferromagnetism is explained by means of the results of structural and optical analyses, where Mn~(3+) and Mn~(4+) ions play a crucial role.