12167-76-9Relevant academic research and scientific papers
New pyrochlore-like compound Cu2OCl2 with S = 1/2
Okabe,Suzuki,Kawashima,Muranaka,Akimitsu
, (2006)
We report here on the magnetic properties of Cu2OCl2, the structure of which can be regarded either as a pyrochlore-like corner-shared tetrahedral network with S = 1/2 or cross-linking chains of edge-sharing CuO2Cl2 squares. The magnetic susceptibility exhibits a broad maximum at approximately 140 K, indicating a low-dimensional feature, and drops at 70 K accompanied with a small specific-heat jump; however, it does not follow the typical S = 1/2 linear chain model. The magnetic susceptibility can be explained by a mean field corrected chain model with a closed value of the intra- and interchain exchange constants; thus, magnetic frustration would be dominant over a low-dimensional feature in Cu 2OCl2. From the band calculation results, we found that the Cu 3d on-site Coulomb interaction is essential to describe the electronic structure of Cu2OCl2. We conclude that Cu 2OCl2 should be regarded as a 3D material that has the potential to combine the pyrochlore-like geometrical frustration and the strong correlation among the Cu 3d electrons. 2006 The Physical Society of Japan.
X-ray diffraction study of multiphase reverse reaction with molten CuCl and oxygen
Marin,Wang,Naterer,Gabriel
, p. 109 - 116 (2011)
The thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen production includes three chemical reactions of hydrolysis, decomposition and electrolysis. The decomposition of copper oxychloride for oxygen production establishes the high-temperature limit of the cycle. At 450-530 °C, copper oxychloride (Cu2OCl2) decomposes to produce a molten salt of cuprous chloride (CuCl, copper I chloride) and oxygen gas. Minimization of the reverse reaction and undesirable products is critical for the proper operation of the Cu-Cl cycle. This paper examines the operating conditions that disfavor the reverse reaction of the oxygen production, and the parameters that maximize the extent of the forward reaction. Experiments were designed to disperse oxygen gas into a molten CuCl bath to study its reaction at 450-500 °C. The composition of the products was quantified with X-ray diffraction measurements. Experimental results indicate that a high decomposition extent of copper oxychloride is obtained at equilibrium when the temperature is higher than 500 °C, and the oxygen pressure is below 2 bar. The thermochemistry data of the reactants and products were also determined and reported. These thermodynamic data provide a key missing gap in the understanding of the Cu-Cl cycle of thermochemical hydrogen production. The data includes the standard formation entropy, enthalpy and Gibbs free energy at different temperatures. Also, in this paper, a thermodynamic analysis is performed to investigate the reverse reaction from the aspects of spontaneity and optimization of the operating parameters. It is found that the optimal operating parameters for minimizing the reverse reaction lie in the pressure range of 1-2 bar and a temperature range of 500-525 °C.
Spin-phonon coupling in melanothallite Cu2OCl2
Araújo,Arévalo-López,Attfield,Paschoal,Ayala
, (2018)
Since interesting magnetodielectric properties were discovered in terbium-based manganites, the search for new magnetodielectric multiferroic materials with high Curie temperatures and strong magnetodielectric coupling has been intense. Recently, it was reported that synthetic melanothalllite, the oxahalide Cu2OCl2, is a spin-driven multiferroic magnetodielectric with Néel temperature around 70 K, which is an exceptionally high critical temperature compared to other spin-driven ferroelectric materials. In this letter, we have probed the spin-phonon coupling in Cu2OCl2 by Raman spectroscopy, showing that the incommensurate magnetic structure induces a spin-phonon coupling in accord with the mean field theory and similar to the one observed in several stretching modes of perovskite compounds.
Assembly of Metal-Anion Arrays within a Perovskite Host. Low-Temperature Synthesis of New Layered Copper-Oxyhalides, (CuX)LaNb2O7, X = Cl, Br
Kodenkandath, Thomas A.,Lalena, John N.,Zhou, Weilie L.,Carpenter, Everett E.,Sangregorio, Claudio,Falster,Simmons Jr.,O'Connor, Charles J.,Wiley, John B.
, p. 10743 - 10746 (1999)
A low-temperature topotactic route is used to assemble metal-anion arrays within a perovskite host. Ion exchange between RbLaNb2O7 and CuX2 (X = Cl, Br) results in a new set of layered copperoxyhalide perovskites, (CuX)LaNb2O7. Rietveld structural analysis of X-ray powder diffraction data confirms the formation of a two-dimensional copper-halide network in the double-layered perovskite interlayer. This new structure type contains unusual CuO2X4 octahedra that corner-share with NbO6 octahedra from the perovskite slab and edge-share with each other along all four equatorial edges. Magnetic susceptibility measurements show that both products exhibit antiferromagnetic transitions below 40 K. Additionally, these materials are found to be low-temperature phases, decomposing completely by 700°C. The synthetic approach described in this work is significant in that it demonstrates how host structures can be used as templates in the directed low-temperature assembly of extended metal-anion arrays.
