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帮忙翻译化学文献中的英文 英译汉7-8
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7. Synthesis of Mesoporous CrN. Mesoporous CrN was synthesized using a method similar to one we reported previously. 35 The XRD patterns for the washed nitride product of the ammonolysis of K2Cr2O7 at 700 °C for 8 h, CrN, can be seen in Figure 1a; this figure confirms the phase purity of the ammonolysis product. The CrN crystallizes in the space group Fm3̅m with a refined lattice parameter of a = 4.1430(2) Å as shown in Figure 1b. The CrN products from ammonolysis at 700 °C show relatively broad diffraction peaks due to the small crystalline domain sizes. The EDX result of the CrN product shows no K peak, which suggests the possible K-containing byproducts have been washed out by DI water. The PXRD refinement of the product obtained shows that the average nitride crystalline domain size is 29 nm. SEM and TEM images were used to observe the surface morphology of the binary nitride products. Figure 2a and b shows SEM images of the CrN, with pores on the scale of 5−10 nm. 8. Chemical, Surface Area, and Conductivity Properties. It is expected that nitrides produced from the ammonolysis of oxides contain residual amounts of oxygen. 21,39 The ammonolysis products of single phase CrN show that the CrN contained <2 wt % oxygen by elemental analysis. The oxide surface layer is most likely from surface hydrolysis due to air exposure of the nitride product produced by ammonolysis. Thus, the oxygen content in the interior of the CrN grains is likely to be lower than that found by elemental analysis. The BET surface area of a 451 mg sample prepared from K2Cr2O7 at 700 °C was 72 m2/g (see Figure 3). The average pore sizes ranged from 10 to 20 nm. There is some microporosity (pore diameter ≤2 nm) that accounts for 1.9 m2/g of the surface area and a total micropore volume of 3 × 10−2 cm3/g. As discussed in the paper reporting the synthesis of metal (oxy)nitrides from Zn-containing oxides, the mesoporosity obtained is a feature of the bulk material and not just porosity induced at the surfaces of the original crystalline oxide grains. 34 The electrical conductivity of mesoporous CrN powder compressed at 35 bar was 54 S/cm, which is about 1 order of magnitude higher than the reported conductivity of carbon-based supports under similar conditions (∼4 S/cm). 40 A reported value for bulk, rocksalt CrN electrical conductivity is 1.1 × 10 3 S/cm. 41 Thus, the conductivity of the compressed mesoporous CrN powder is approximately 2 orders of magnitude lower than that of the bulk material, presumably due to both the porosity and the weak particle−particle contacts at low pressure. |
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7。介孔氮化铬的合成。介孔氮化铬合成使用了我们以前的报告的类似方法。 35图1a可以看到重铬酸钾在700℃下8小时的氨解洗涤氮化产物------氮化铬的X射线衍射图谱，该图证实了氨解产物的相纯度。氮化铬结晶空间群Fm3m中精确的晶格参数为：a =4.1430（2）埃，如图1b。氮化铬产品在700℃下氨解，由于小的结晶域尺寸显示出相对宽的衍射峰。 氮化铬产品的EDX结果没有K峰，表明可能K-副产品都被去离子水冲走了。产物的PXRD精确化显示氮化物结晶体平均尺寸为29纳米。 用SEM和TEM图像来观察二元氮化物产品的表面形貌。图2a和b显示了CrN的SEM图像，有5-10纳米大小的孔。 8。化学结构，表面积和导电性能。氧化物氨解生成氮化物预期含有残留氧。 21,39经元素分析，单相氮化铬的氨解产物表明氮化铬含有<2％（重量）的氧。由于通过氨解作用所产生的氮化物产物暴露于空气中，氧化表面层是最有可能从表面水解。因此，在氮化铬颗粒内部的氧含量可能比通过元素分析发现的更低。一个451毫克从重铬酸钾在700℃下制备的样品BET表面积为72平方米/克（参见图3）。孔径平均范围为10至20nm。有一些表面积1.9平方米/克和总微孔体积微孔3×10-2立方厘米/克微孔（孔径≤2纳米）。正如本文报道的从含Zn的氧化物合成金属（氧）氮化物所讨论的，中孔为主体材料的一个特征，不仅仅是原始结晶氧化物颗粒表面引起的孔隙。 34在35巴压缩的中孔性CrN粉末的电导率为54秒/厘米，比已报道的相似条件碳载体的电导率（〜4的S /厘米）高一个数量级。 40零星的报告值，岩盐的CrN电导率为1.1×103 S / cm。 41因而，压缩的介孔氮化铬粉末的导电率比该应用较少的材料低约2个数量级，这可能是由于低压力条件下两者的孔隙和颗粒与颗粒的接触较弱。 低一个数量级为小10倍。 |
2楼2013-12-01 20:59:13
