Structural transformation, spectroscopic characterization and magnetic properties of La1−xGdxCoO3

Abstract La 1−x Gd x CoO 3 for x x ≥ 0.2 . The lattice volume systematically decreases as x increases. The analysis of the Co 2p 3/2 xps spectra indicates that the Co ions are at both +3 and +8/3 valence states, and the calculated oxygen content is about 2.93 per formula unit. The bending vibration of the Co O bond linearly shifts from 429 cm −1 to 482 cm −1 with the increasing x, and it is coincident with the increasing Co O Co angle. The shoulder peak at approximately 575 cm −1 becomes obviously wide with the increasing doping Gd 3+ content owing to the magnetic interactions of the Gd 3+ ions with the surrounding CoO6 octahedra. The energy band gap slightly increases from about 2.40 eV to about 2.75 eV as the structure transforms from the rhombohedral to the orthorhombic structure. The magnetic properties are ferrimagnetic with x = 0.05, 0.3 and 0.7. However, the calculated Curie-Weiss temperature and constant of La 0.3 Gd 0.7 CoO 3 are not reasonable, it is probably due to a nonlocalized electronic state.