Caractérisation de la liaison Cu-O dans les oxydes mixtes CuMM′O4 (M = Fe, Cr; M′ = Al, Ga, Mn). Corrélation avec l'effet Jahn-Teller

Abstract

Les paramètres caractéristiques de la liaison Cu(II)‐O dans les oxydes CuMM'O4 cubiques ou quadratiques peuvent être correlés avec l'intensité de l'effet Jahn‐Teller. Les manganites de cuivre possédent le caractére d'oxyde à valence mixte, l'équilibre étant d'autant plus déplacé dans le sens 2 que la teneur en cuivre tétraédrique est plus élevée.

Cation Migration and Coercivity in Mixed Copper–Cobalt Spinel Ferrite Powders

“…The vari- (Table 5). A comparison of the experimental data on copper ferrite with the data for mixed copper ferrites prepared by the usual ceramic method (29,30) leads to the conclusion that in the SC sample and the Q sample annealed at 500°C, &10% of the Cu> ions are in tetrahedral coordination. Heat treatment of the quenched samples at 300°C induces the migration of the Cu> ions from the tetrahedral to the octahedral sites.…”

Effects of Cu/Fe ratio on structure and performance of attapulgite supported CuFeCo-based catalyst for mixed alcohols synthesis from syngas

“…Haber et al [42] showed that the Cu 2+ BE of 933 eV ∼ 934 eV is indicative of CuO species. Li [43] and Lenglet et al [44] reported that copper BE in relation with its tetrahedral CuO(A) or octahedral composite metal oxides (B) environment of Cu 2+ cations in spinel structure, Cu A 2+ at 933.2 eV ∼ 933.8 eV and Cu B 2+ at 934.7 eV ∼ 936.2 eV. The BE datas of Cu (2p 3/2 ) are showed in Table 2, which indicate that tetrahedral and octahedral Cu 2+ cations existed in all the catalysts.…”

On the Mn promoted synthesis of higher alcohols over Cu derived ternary catalysts

“…The Cu 2p 3/2 binding energy values in the oxidized catalysts are in the range of 932.6-933.8 eV with Cu 2p 3/2 -2p 1/2 spin-orbit splitting of 20.0 ± 0.1 eV, characteristic of CuO. [38][39][40][41] The shake-up satellites at ∼942 eV and ∼962 eV are attributed to shake-up transitions by ligand-to-metal 3d charge transfer 41 43,44 According to the literature, higher Cu 2p binding energies (in the range of 933.4-934.5 eV) are associated with a higher percentage of copper in octahedral coordination, 45,46 while lower values show a higher percentage of tetrahedrally coordinated copper cations. 47 Therefore, the shift of the binding energy of Cu 2+ to higher values in the K-CuMnAl catalyst can be related to both the coordination of 44,48 In addition to the main peak, the Cu 2p spectrum of the K-CuMnAl catalyst features an additional shoulder at lower binding energy.…”