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

• The structure is rhombohedral for x < 0.2 and orthorhombic for x ≥ 0.2. FT-IR is influenced by Gd3+ magnetic moments.
• The calculated oxygen content is about 2.93 per formula unit.
• The energy gap increases by 0.3 eV as the structure transforms at x ≥ 0.2.
• The magnetic interaction is ferrimagnetic and has nonlocalized electronic states.

La1−xGdxCoO3 for x < 0.2 crystallize in the rhombohedral structure, and it is orthorhombic for x≥0.2x≥0.2. The lattice volume systematically decreases as x increases. The analysis of the Co 2p3/2 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 CoO bond linearly shifts from 429 cm−1 to 482 cm−1 with the increasing x, and it is coincident with the increasing CoOCo angle. The shoulder peak at approximately 575 cm−1 becomes obviously wide with the increasing doping Gd3+ content owing to the magnetic interactions of the Gd3+ 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 La0.3Gd0.7CoO3 are not reasonable, it is probably due to a nonlocalized electronic state.