Instituto de Ciencia de Materiales de Barcelona, ICMAB-CSIC, Campus de la UAB, Bellaterra 08193, Spain.
Inorg Chem. 2010 Dec 6;49(23):10977-83. doi: 10.1021/ic101420c. Epub 2010 Nov 4.
The silver-copper mixed oxide AgCuO(2) (also formulated as Ag(2)Cu(2)O(4)) possesses a peculiar electronic structure in which both Ag and Cu are partially oxidized, with the charge being delocalized among the three elements in the oxide. Accordingly, a quasi-metallic behavior should be expected for this oxide, and indeed bulk transport measurements show conductivity values that are orders of magnitude higher than for other members of this novel oxide family. The presence of silver makes thermal sintering an inadequate method to evaluate true conductivity, and thus such measurements were performed on low density pellets, giving an underestimated value for the conductivity. In the present work we present a new synthetic route for AgCuO(2) based on mild hydrothermal reactions that has yielded unprecedented large AgCuO(2) single-crystals well over 1 μm in size using temperatures as low as 88 °C. We have used a dual beam instrument to apply nanocontacts to those crystals, allowing the in situ measurement of transport properties of AgCuO(2) single crystals. The results show a linear relationship between applied current and measured voltage. The conductivity values obtained are 50 to 300 times higher than those obtained for bulk low density AgCuO(2) pellets, thus confirming the high conductivity of this oxide and therefore supporting the delocalized charge observed by spectroscopic techniques.
银铜混合氧化物 AgCuO(2)（也可表示为 Ag(2)Cu(2)O(4)) 具有独特的电子结构，其中 Ag 和 Cu 均部分氧化，电荷在氧化物中的三个元素之间离域。因此，这种氧化物应该具有类金属行为，而实际上，体相输运测量显示出的电导率值比该新型氧化物家族的其他成员高出几个数量级。银的存在使得热烧结成为评估真实电导率的不合适方法，因此这些测量是在低密度颗粒上进行的，这导致电导率值被低估。在本工作中，我们提出了一种基于温和水热反应的 AgCuO(2)新合成途径，该途径在低至 88°C 的温度下使用，已成功获得了尺寸超过 1 μm 的前所未有的大尺寸 AgCuO(2)单晶。我们使用双束仪器将纳米接触施加到这些晶体上，从而可以原位测量 AgCuO(2)单晶的输运性质。结果表明，施加电流与测量电压之间存在线性关系。所获得的电导率值比低密度块状 AgCuO(2)颗粒高 50 至 300 倍，从而证实了该氧化物的高电导率，并因此支持了光谱技术观察到的离域电荷。
