Crystal structure and magnetic properties of CoTiO3

High-resolution EELS investigation of the electronic structure of ilmenites

“…In order to investigate the electronic structure, we first assessed the formal coordination, valency, and spin state of the transition metal atoms in the series. From the comparison between experimental and theoretical L 23 edges, modeled using ligandfield multiplet calculations, 23,24 we established unambiguously the presence of tetravalent Ti and divalent transition metal in the high-spin state along the series and confirmed in particular the Fe 2+ formal valency in FeTiO 3 . These results are consistent with the monotonic decrease of the M-O interatomic distance observed experimentally in these compounds when increasing the atomic number of the transition metal.…”

“…The parameters used in the calculation are the same as those used in Ref. 28 to calculate the Ti-L 23 in FeTiO 3 . Except for small intensity variations, visible on the first prominent peak ͑at 458 eV͒, the experimental spectra are very similar and characteristic of Ti 4+ in an octahedral symmetry.…”

“…[1][2][3][4][5][6][7][8][9][10][11] At room temperature and under normal pressure, they adopt an ordered corundum structure [1][2][3][4] of space group R3, the ilmenite structure, in which M 2+ and Ti 4+ form alternating layers along the rhombohedral axis of the crystal, with oxygen layers between them. This structure, displayed in Fig.…”

“…Similarly, the Fe 2+ +Ti 4+ → Fe 3+ +Ti 3+ intervalent charge transfer in natural FeTiO 3 is also explained by an enhanced atomic orbital overlap between Ti and Fe under pressure. [14][15][16] This charge transfer, also named hopping small polaron, is considered as the dominant conduction mechanism in FeTiO 3 . The understanding of the electronic structure of these compounds thus appears as a key parameter to explain their electrical properties.…”

Magnetic properties and heat capacity of CoTiO3nanopowders prepared by stearic acid gel method

“…An antiferromagnetic transition was detected at the Ne´el temperature, T N ¼ 38 K, as reported for single crystals [26]. In the hexagonal crystallographic structure, the magnetic interactions of neighbouring Co 2þ spins are ferromagnetic within the a-b planes and antiferromagnetic between adjacent a-b planes [27,28]. The sample exhibits a fully reversible transition, representative of a genuine antiferromagnet.…”