STRUCTURAL PHASE TRANSITION AND OPTO-MAGNETIC PROPERTIES OF MN-DOPED BATIO3

Abstract

Multiferroic BaTi_1-xMn_xO₃ (0.0 ≤ x ≤ 0.1) materials were synthesized by the solid-state reaction method. The influence of Mn substitution for Ti on the crystalline structure and opto-magnetic property of BaTi_1-xMn_xO₃ samples were investigated. The results revealed that the structure of the material sensitively depended on Mn dopant content, x, and transformed gradually from the tetragonal (P4mm) phase to the hexagonal (P6₃/mmc). The presence of Mn impurity levels combined with the complex levels due to lack of oxygen defects and lattice defects created overlapping lattice, expanded the absorption band and provided the absorption edge toward longer wavelength. We also point out that Mn³⁺ and Mn⁴⁺ ions substitute for Ti⁴⁺ and prefer locating in the tetragonal and hexagonal BaTiO₃ structures, respectively, in which the hexagonal phase constitutes soon as x = 0.01. Particularly, all the samples exhibit roomtemperature ferromagnetism. Ferromagnetic order increases with increasing x from 0.0 to 0.02, but decreases as x = 0.04. We think that ferromagnetism in BaTi_1-xMn_xO₃ is related to lattice defects and/or exchange interactions between Mn³⁺ and Mn⁴⁺ ions.