Co掺杂的YBa2Cu2O6+δ的氧非计量和氧渗透性能研究

研究钴离子部分取代铜离子对YBa2 Cu3 O6+δ的氧非计量值δ和氧渗透率的影响 .对于钴替代的样品 ,氧非计量的绝对值变大 ,且其数值不再随温度和氧分压的变化发生显著变化 .YBa2 Cu2 CoO6+δ样品在中、高温具有可观的氧渗透率 .对于厚度为 1.2mm的致密YBa2 Cu2 CoO6+δ样品 ,在 85 0℃时 ,只要在样品两端施加较小的氧分压差(PO2 =2 1.2kPa、PO2 =10 1Pa) ,其氧渗透率即可达 5 7μmol/cm2 s,明显高于YBa2 Cu3 O6+δ的氧渗透率 (31μmol/cm2s) .YBa2 Cu2 CoO6+δ的高氧渗透率在结构上可被归结为位于晶胞基面上的氧离子和氧空位的均匀分布     

(RBaCo2O5 δ(Pr,Sm,Y)体系的滞弹性内耗研究

本文对双钙钛矿结构RBaCo2O5 δ(Pr, Sm, Y)化合物进行了内耗研究.随稀土元素R的不同该材料体系存在着不同的晶体结构, 并导致了氧缺陷不同的驰豫行为.体系内耗谱图中呈现的一个驰豫型内耗峰被认为是由于[Roδ]层中额外氧的运动引起的.SmBaCo2O5 δ体系中在360 K附近还观察到一个相变型内耗峰,它伴随有模量的变化.     

La2 NiO4+δ体系相分离现象的低频内耗研究

La2 NiO4 δ体系额外氧δ =0 .0 71,0 .110 ,0 .135 ,0 .14 0样品中存在着一个间隙氧弛豫运动引起的低频内耗峰 ,其内耗峰峰位置随额外氧的增多向高温移动 .而额外氧处于其间位置δ =0 .0 87样品中则出现了两个弛豫型内耗峰 ,分析认为它们源于体系相分离后形成的不同一维有序结构中间隙氧的跳跃 .此外 ,额外氧δ=0 .0 38样品中也观察到两个弛豫型内耗峰 ,其中低温峰性质与上相同 ,而高温内耗峰则可能对应于体系相分离后形成的低温四方相中氧原子的跳跃弛豫     

GdBaCo2O5+δ体系的滞弹性内耗研究

GdBaCo₂O_5+δ体系的低频内耗研究表明：体系中存在一个由额外氧运动引起的弛豫内耗峰；额外氧δ对这个弛豫内耗峰的大小、峰形及峰位有较大影响，反映了额外氧状态随δ而变化.当δ=0.005，体系中额外氧含量很少而接近零时，相应的内耗峰消失；δ达到一定数量后，出现弛豫内耗峰.由δ=0.278，0.407，0.421，0.515样品的弛豫内耗峰分析可得到体系随δ不同存在着三种不同的额外氧形态.此外，δ=0.421及0.515的样品在360K附近存在一个相变内耗峰，它对应着体系中的金属—绝缘体转变. 关键词： 2O_5+δ')" href="#">GdBaCo₂O_5+δ 额外氧 内耗峰     

火焰原子荧光光谱法测定矿石样品中的银

为满足矿产资源领域地质找矿的检测工作需要,寻找一种操作便捷、重现性好、检出限低的检测方法,进行银元素的定量分析测试。通过对样品取样重量、复溶盐酸用量等参数进行条件优化试验,选出最优前期处理条件;对火焰原子荧光光谱仪进行条件试验,针对灯电流、燃气气流量等关键参数进行单一变量试验,最终确立了仪器最佳测试条件;测试方法精密度为精密度为1.80%～4.52%,准确度为0.46%～1.82%,检出限为0.4g/t。本方法具有稳定性好,灵敏度高,分析效率快等特点,适合在样品量多、精度要求高的实验室间推广。     

La2-xNdxCuO4+δ(0.1≤x≤1.2)体系中滞弹性弛豫与相变内耗研究

通过对La_2-xNd_xCuO_4+δ(0.1≤x≤1.2)体系中滞弹性弛豫与相变内耗性能的研究发现,当0.1≤x≤1.0时,在250K左右存在一个与间隙氧有关的弛豫内耗峰,并且当0.1≤x≤0.4时,弛豫内耗峰峰高随着x值的增大而升高,此时体系为正交结构;当0.5≤x≤1.0时,体系在宏观上呈现四方结构,此时内耗峰峰高随着x< 关键词： 2-xNd_<i>xCuO_4+δ')" href="#">La_2-xNd_<i>xCuO_4+δ 间隙氧 弛豫内耗峰 相变内耗峰     

Investigation of sulfur speciation in particles from small coal-burning boiler by XANES spectroscop

Sulfur K-edge X-ray absorption near-edge structure （XANES） spectroscopy was employed to study the speciation of sulfur in raw coal, ash by-product and fine particulate matter from a small coal-burning boiler. By means of least square analysis of the XANES spectra, the major organic and inorganic sulfur forms were quantitatively determined. The results show that about 70% of the sulfur in raw coal is present as organic and a minor fraction of the sulfur occurs as other forms： 17% of pyrite and 13% of sulfate. While in bottom ash, fly ash, and PM2.5, the dominant form of sulfur is sulfate, with the percentage of 80,79 and 94, respectively. Moreover, a number of other reduced sulfur including thiophenic sulfur, element sulfur and pyrrhotite are also present. During coal combustion, most of organic sulfur and pyrite were oxidized and released into the atmosphere as SO2 gas, part of them was converted to sulfate existing in coal combustion by-products, and a small part of pyrite was probably reduced to elemental sulfur and pyrrhotite. The results may provide information for assessing the pollution caused by small boiler and developing new methods for the control of SO2 pollution.     

Characteristics of element concentration of daytime and nighttime PM2.5 in the suburbs of Shanghai using Synchrotron XRF

The characteristics of daytime and nighttime suburbs PM_2.5 in Shanghai were analyzed by synchrotron based X-ray fluorescence during the period of October, 2006 and November, 2007. The mass concentrations of nighttime PM_2.5 was approximately two times that of daytime PM_2.5. Some elements, such as Zn, Cu, Mn, Cl were found enriched at night. The local sources might have significant contribution to the nighttime PM_2.5 pollutions.     

Transfer characterization of sulfur from coal-burning emission to plant leaves by PIXE and XANES

The impact of coal-burning emission on sulfur in camphor leaves was investigated using Proton Induced X-ray Emission (PIXE) and synchrotron radiation technique X-ray Absorption Near-Edge Structure (XANES) spectroscopy. The PIXE results show that the sulfur concentrations in the leaves collected at the polluted site are significantly higher than those in controls. The Sulfur XANES spectra show the presence of organic (disulfides, thiols, thioethers, sulfonates and sulfoxides) and inorganic sulfur (sulfates) in the leaves. The inorganic sulfur in the leaves of camphor tree polluted by coal combustion is 15% more than that of the control site. The results suggest that the long-term coal-burning pollution resulted in an enhanced content of the total sulfur and sulfate in the leaves, and the uptake of sulfur by leaves had exceeded the metabolic requirement of plants and the excess of sulfur was stored as SO₄^2－. It can monitor the sulfur pollution in atmosphere.