Stabilization of the high-spin state of Co3+ in LaCo1-xRhxO3

Article

关键词: DENSITY-FUNCTIONAL THEORY;    TRANSITIONS;    LACOO3;    METAL;    ION;   

DOI  :  10.1103/PhysRevB.85.134401

来源: SCIE

【 摘 要 】

Rhodium doping in the LaCo1-xRhxO3 perovskite series (x = 0.02-0.5) has been studied by use of x-ray diffraction, electric transport, and magnetization measurements, complemented by electronic structure GGA+U calculations in a supercell for different concentration regimes. No charge transfer between Co3+ and Rh3+ was evidenced. The diamagnetic ground state of LaCoO3, based on Co3+ in low-spin (LS) state, is disturbed even by a small doping of Rh. The driving force is the elastic energy connected with incorporation of a large Rh3+ cation into the matrix of small LS Co3+ cations, which is relaxed by formation of a large Co3+ in the high-spin (HS) state in the next-nearest sites to the inserted Rh atom. With increasing temperature, the population of Co3+ in HS state increases through thermal excitation, and a saturated phase is obtained close to room temperature, consisting of a nearest-neighbor correlation of small (LS Co3+) and large (HS Co3+ and LS Rh3+) cations in a kind of double perovskite structure. The stabilizing role of the elastic and electronic energy contributions is demonstrated by the supercell calculations for dilute Rh concentration compared to other dopants with various trivalent ionic radius.

【 授权许可】

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