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Synthesis and characterization of gold-containing oxides of K2NiF4 or Nd2CuO4 structure type
Gold Bulletin ( IF 2.1 ) Pub Date : 2018-04-17 , DOI: 10.1007/s13404-018-0227-2
Jerffersson Rodríguez Delgado , Verónica García Rojas , Gilles H. Gauthier

In this work, different materials of Nd2CuO4 and K2NiF4 Ruddlesden-Popper structure have been prepared by solid-state reaction in air and high temperatures. The powders of mixed oxides, of general formula La2Li0.5M0.5 − xAuxO4 (M = Cu, Ni), were prepared from [Au(NH3)4](NO3)3 as gold source. The stoichiometric proportions of the all reagents (including La2O3, NiCO3, CuO) were grounded with a LiOH excess as mineralizer, pressed to form into pellets and heated in static air at temperatures between 750 and 850 °C for several hours. Structural characterization of the synthesized oxides using X-ray diffraction (XRD) are presented. La2Li0.5Au0.5O4, La2Li0.5Cu0.5O4, and La2Li0.5Ni0.5O4, three previously known oxides, were obtained. As expected, La2Li0.5Ni0.5O4 and La2Li0.5Cu0.5O4 consist of an ordered K2NiF4 Ruddlesden-Popper structure, while the La2Li0.5Au0.5O4 compound exhibits a Nd2CuO4 type structure. On the other hand, the preparation of the new proposed group La2Li0.5M0.5 − xAuxO4 (x = 0.0125–0.5) containing gold and nickel/copper simultaneously, under the studied conditions, was not possible. The experimental results revealed that the host structures are intolerant with respect to M (Cu or Ni) and Au cation double substitution. The difficulty to obtain the new phases is discussed regarding the exceptional instability displayed by the trivalent state of gold ion (Au3+) and the soft interactions of this specie with the lithium cation. Finally, the monophasic oxides, more interesting in terms of catalytic activity, were analyzed by temperature-programmed reduction (TPR-H2).

中文翻译:

K2NiF4或Nd2CuO4结构型含金氧化物的合成与表征

在这项工作中,通过在空气和高温下的固态反应制备了 Nd2CuO4 和 K2NiF4 Ruddlesden-Popper 结构的不同材料。混合氧化物粉末,通式为 La2Li0.5M0.5 - xAuxO4 (M = Cu, Ni),由 [Au(NH3)4](NO3)3 作为金源制备。将所有试剂(包括 La2O3、NiCO3、CuO)的化学计量比例与过量的 LiOH 作为矿化剂一起研磨,压制成颗粒并在 750 至 850 °C 的静态空气中加热数小时。介绍了使用 X 射线衍射 (XRD) 对合成氧化物的结构表征。获得了三种先前已知的氧化物 La2Li0.5Au0.5O4、La2Li0.5Cu0.5O4 和 La2Li0.5Ni0.5O4。正如预期的那样,La2Li0.5Ni0.5O4 和 La2Li0.5Cu0.5O4 由有序的 K2NiF4 Ruddlesden-Popper 结构组成,而 La2Li0. 5Au0.5O4 化合物具有 Nd2CuO4 型结构。另一方面,在所研究的条件下,不可能同时制备含有金和镍/铜的新提议的 La2Li0.5M0.5 - xAuxO4 (x = 0.0125–0.5) 组。实验结果表明,主体结构不耐受 M(Cu 或 Ni)和 Au 阳离子双取代。关于金离子 (Au3+) 的三价态所显示的异常不稳定性以及该物种与锂阳离子的软相互作用,讨论了获得新相的难度。最后,在催化活性方面更有趣的单相氧化物通过程序升温还原 (TPR-H2) 进行分析。在所研究的条件下,不可能同时含有金和镍/铜的 5M0.5 - xAuxO4 (x = 0.0125–0.5)。实验结果表明,主体结构不耐受 M(Cu 或 Ni)和 Au 阳离子双取代。关于金离子 (Au3+) 的三价态所表现出的异常不稳定性以及该物种与锂阳离子的软相互作用,讨论了获得新相的难度。最后,在催化活性方面更有趣的单相氧化物通过程序升温还原 (TPR-H2) 进行分析。在所研究的条件下,不可能同时含有金和镍/铜的 5M0.5 - xAuxO4 (x = 0.0125–0.5)。实验结果表明,主体结构不耐受 M(Cu 或 Ni)和 Au 阳离子双取代。关于金离子 (Au3+) 的三价态所表现出的异常不稳定性以及该物种与锂阳离子的软相互作用,讨论了获得新相的难度。最后,在催化活性方面更有趣的单相氧化物通过程序升温还原 (TPR-H2) 进行分析。实验结果表明,主体结构不耐受 M(Cu 或 Ni)和 Au 阳离子双取代。关于金离子 (Au3+) 的三价态所表现出的异常不稳定性以及该物种与锂阳离子的软相互作用,讨论了获得新相的难度。最后,在催化活性方面更有趣的单相氧化物通过程序升温还原 (TPR-H2) 进行分析。实验结果表明,主体结构不耐受 M(Cu 或 Ni)和 Au 阳离子双取代。关于金离子 (Au3+) 的三价态所显示的异常不稳定性以及该物种与锂阳离子的软相互作用,讨论了获得新相的难度。最后,在催化活性方面更有趣的单相氧化物通过程序升温还原 (TPR-H2) 进行分析。
更新日期:2018-04-17
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