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我们曾用HREM的方法研究铜的初期氧化物,确定了Cu_4O,Cu_8O和Cu_64O等几种初期氧化物的存在和结构。本文报导我们继续上述研究又获得的另一铜的初期氧化产物—Cu_4O_(1-0.25)。它比Cu_4O少1/4氧原子,可看作Cu_4O的缺氧结构。这种缺氧结构的氧原子排列有几种形式,它们具有相同的电子衍射谱,但HREM像的特征却不相同。本研究报导其中的三种,称其为α、β和γ型。Cu_4O_(1-0.25)是在与生成Cu_4O相同的氧化条件下生成的,常常可以观察到Cu_4O与Cu_4O(1-0.25)相毗邻存在。图1a是Cu_4O[100]取向的晶体结构投影,黑点表示Cu原子,圈表示氧原子的分布,圈中的数字表示氧原子的高度,小方框是Cu_4O单胞的投影。从图可知,处于O高度和1/2高度的氧原子列密度是相同
We have used HREM method to study the initial copper oxide, to determine the existence and structure of several initial oxides Cu_4O, Cu_8O and Cu_64O. This article reports another copper oxidation product, Cu_4O_ (1-0.25), which we continue with the above study. It is less than 1/4 oxygen atoms Cu_4O, can be seen as Cu_4O hypoxia structure. The oxygen atoms of this oxygen-deficient structure are arranged in several forms that share the same electron diffraction pattern, but the characteristics of HREM images are not the same. Three of these studies reported that they are alpha, beta and gamma. Cu_4O_ (1-0.25) is formed under the same oxidation conditions as Cu_4O. It is often observed that Cu_4O exists adjacent to Cu_4O (1-0.25). Figure 1a shows the crystal structure of the Cu_4O [100] oriented projection. The black dots represent Cu atoms, the circles represent the distribution of oxygen atoms, the numbers in the circles represent the height of oxygen atoms, and the small squares represent the projections of Cu_4O unit cells. As can be seen from the figure, the density of oxygen atom columns at the O-height and the ½-height are the same