Si(Li)谱仪测量X射线荧光谱中CrK_β谱线化学位移的探索

采用放射源２４１Ａｍ５９．６ｋｅＶγ射线分别激发金属Ｃｒ、Ｃｒ２Ｏ３和Ｋ２ＣｒＯ４，用Ｓｉ（Ｌｉ）谱仪比较测量其Ｋｘ射线的能量。实验表明Ｋ２ＣｒＯ４中ＣｒＫβ能峰相对于金属Ｃｒ有２．１２±０．２７ｅＶ的位移。     

CuSO4·5H2O在用KBr压片法制样时所发生的固相反应的研究

用Ｘ射线衍射法和ＦＴ－ＩＲ法研究了ＣｕＳＯ４·５Ｈ２Ｏ在用ＫＢｒ压片法制样过程中所发生的固相反应．主要产物为：Ｋ２Ｃｕ（ＳＯ４）２·６Ｈ２Ｏ和ＣｕＢｒ２。     

对Bi-2212超导体中的Raman谱指认

本文对Ｂｉ２－ｘＰｂｘＳｒ２ＣａＣｕ２Ｑδ（ｘ＝０￣０．５）系列样吕以及在真空下不同温度退火的Ｂｉ１．６Ｐｂ０．４Ｓｒ２ＣａＣＵ２Ｏδ样品进行了Ｘ射线衍射和Ｒａｍａｎ谱实验研究。测量表明,随着退火温度的升高,ａ,ｂ,ｃ轴晶格常数增加,与Ｏ（１）ＣｕＢｇ模式相关的２９４ｃｍ＾－１的峰强减少,峰位红移。研究结果进一步表明,４６４ｃｍ＾－１和６３０ｃｍ＾－１峰分别与Ｏ（３）ＢｉＡ１ｇ和Ｏ（２）ＳｒＡ１ｇ     

Bi2222相单晶生长的相关问题研究

从名义组份Ｂｉ２．４Ｓｒ２ＰｒＣｕ２Ｏｙ生长出一种新的Ｂｉ２２２２相单晶，其实际组份测定为Ｂｉ２Ｓｒ１．５Ｐｒ２．５Ｃｕ２Ｏｙ．用Ｘ射线衍射对单晶的结构进行了表征，并且研究了该单晶生长中Ｂｉ２２０１和Ｂｉ２２１２相的交生等相关问题．另外，如果从名义组份为Ｂｉ２．４Ｓｒ１．５Ｐｒ２．５Ｃｕ２Ｏｙ出发，得到的却是Ｐｒ２ＣｕＯ４单晶．     

高温超导薄膜(Y0.6Ho0.4)Ba2Cu3O7-δ/SAT/MgO的制备

用脉冲激光沉积法在先在ＭｇＯ衬底上制备一层Ｓｒ２（ＡｌＴａ）Ｏ６薄膜作为过渡层,再制备（Ｙ０．６Ｈｏ０．４）Ｂａ２Ｃｕ３Ｏ７－δ超导薄膜,新超导薄膜的零电阻温度Ｔｃ０为８９Ｋ,临界电流密度Ｊｃ为２．３＊１０＾６Ａ／ｃｍ＾２（７７Ｋ）,用Ｘ射线衍射仪及扫描电子显微镜分析了薄膜特性。     

Ni／Al2O3催化剂上CH4／CO2重整反应积碳的研究

采用Ｘ光电子能谱（ＸＰＳ）和脉冲反应技术考察了９７３Ｋ下经不同方法处理后的Ｎｉ／Ａｌ２Ｏ３催化剂表面的积碳，单独用ＣＨ４或ＣＯ处理后的催化剂在２８３．６ｅＶ左右出现了一个新的Ｃｌｓ峰，可归属为金属碳化物，对ＣＨ４，ＣＯ处理过的催化剂用ＣＯ２处理后发现，结合能约为２８３．６ｅＶ的Ｃｌｓ峰强度明显降低，但由ＣＯ处理的催化剂的积碳的活性不如由甲烷生成的积碳活性好，ＣＯ歧化反应可能是导致镍催化剂失活的主要     

MOCVD法在金属基体上制备YBCO超导带

本报道了用ＭＯＣＶＤ静态和动态沉积两种工艺制备ＹＢＣＯ超导带的实验结果。以Ｙ（ＴＭＨＤ）３、Ｂａ（ＴＭＨＤ）２和Ｃｕ（ＴＭＨＤ）２为挥发源，Ｏ２气为反应剂，高纯Ａｒ气为载流气体，在静止和以１０－１５ｃｍ／ｈ带速移动的金属银基体上，制出了有强烈ｃ－轴取向的ＹＢＣＯ超导带。静态沉积样品的Ｊｃ达到１．０４×１０＾４Ａ／ｃｍ＾２，动态沉积样品的Ｊｃ达到１．４×１０＾４Ａ／ｃｍ＾２（７８Ｋ，０Ｔ）。对改…     

取代苯胺基亚胺二茂铁类化合物莫斯鲍尔谱及分子光谱研究

本文报道了６种取代苯胺基亚胺二茂铁类化合物Ｒ－Ｎ＝ＣＨ－Ｆｅ（－Ｆｅ为二茂铁基，Ｒ为－Ｃ６Ｈ４Ｘ，（Ｘ＝Ｈ，４－Ｂｒ，４－ＯＨ，２－ＣＨ３，４－ＣＯＯＨ）及４－ＮＨＣ６Ｈ４ＮＯ２）的Ｍｏｓｓｂａｕｅｒ谱数据，其化学位移分别为（ｍｍ．ｓ＾－１）：０．３２３，０．３３２，０．３３８，０．３２４，０．３１５和０．３１０。其四极矩分裂值分别为（ｍｍ．ｓ＾－１）：２．２６３，２．２８５，２．２８７，２．２１     

KH_2PO_4和（CH_3NHCH_2COOH）_3CaCl_2在高压下的状

在活塞圆筒式Ｐ～Ｖ关系测量装置上，研究了ＫＨ＿２ＰＯ＿４（ＫＤＰ）和（ＣＨ＿３ＮＨＣＨ＿２ＣＯ－ＯＨ）＿３ＣａＣＩ＿２［Ｔｒｉｓ－ｓａｒｃｏｓｉｎｅｃａｌｃｉｕｍｃｈｌｏｒｉｄｅ（ＴＳＣＣ）］在室温下、４．５ＧＰａ内的ｐ～Ｖ关系。实验结果表明：ＫＤＰ在２．１ＧＰａ左右有一个相变；ＴＳＣＣ在０．８ＧＰａ和３．２ＧＰａ左右各有一个相变。本工作还给出了它们在相变前后的状态方程，以及它们的格临爱森参数γＯ、体积模量Ｂ＿ｏ和Ｂ＿ｏ的压力导数Ｂ＿ｏ。     

在Ar和Xe低温基体中Fe（CO）3与CO扩散控制反应研究

本文用２８０ｎｍ脉冲激光光解被Ａｒ和Ｘｅ基体隔离的Ｆｅ（ＣＯ）５以产生配位不饱和的Ｆｅ（ＣＯ）３。用傅里衰变换红外光谱仪实时监察光解停止后Ｆｅ（ＣＯ）３和ＣＤ的复合，并以Ｓｍｏｌｕｃｈｏｗｓｋｉ扩散控制反应动力学理论模型求得Ｆｅ（ＣＯ）３与ＣＯ的反应半径为４．０×１０＾－１０ｍ，ＣＯ在１０Ｋ的Ａｒ和Ｘｅ基体中的扩散系数分别为２．２×１０＾－２３ｍ＾２／ｓ和４．５×±∩＾－２３ｍ＾２／ｓ。     

Coexistence of two different Cr ions by self-doping in half-metallic CrO2 nanorods

We investigated the physical properties of Cr ions in half-metallic CrO(2) using 53Cr nuclear magnetic resonance (NMR). The 53Cr NMR spectra showed two peaks with a similar intensity instead of the single peak anticipated from a uniform single valence Cr(+4). Both Cr peaks exhibited a strong anisotropy in the hyperfine field and similar values in the enhancement factor and T2 relaxation time. These results suggest the coexistence of two different Cr ions (provisionally, Cr(+4 +/- 1/3)) by a self-doping effect, which is a likely origin of the metallic ferromagnetism in CrO(2).     

Low photoemission intensity near induced by the surface relaxed structure of CrO2(001)

Based on first principles calculations we find that CrO2(001) will form a relaxed structure at its surface, at which each surface Cr atom is surrounded by four oxygen atoms in a distorted tetrahedral configuration. This tetrahedral environment has important effects on the electronic structure, leading to an inversion of the t2g-eg splitting of Cr 3d orbitals. Two 3d electrons of the surface Cr ion will fully occupy the doublet eg, which becomes lower in energy than the t2g, leaving the t2g orbitals empty. The consequence is that the Fermi level lies in a gap between the eg and t2g for a local electronic structure at the surface. This finding is consistent with and explains the extremely low photoemission intensity near EF at CrO2(001) [K?mper et al., Phys. Rev. Lett. 59, 2788 (1987)].     

Strong anisotropy of projected 3d moments in epitaxial CrO2 films

Soft x-ray magnetic circular dichroism (XMCD) spectra have been investigated for different crystallographic projections of CrO2. Strong anisotropic orbital Cr 3d contributions and a change of sign of the XMCD signal is observed and attributed to t(2g) majority states near the Fermi level. Additionally, moment analysis exhibits anisotropic behavior in the projected spin contributions of CrO2 assigned to a strong magnetic dipole term T(z), consistent with an intrinsic magnetic easy axis behavior along the CrO2 [001] axis. A reduced projected isotropic Cr 3d spin moment has been interpreted in terms of hybridization with oxygen.     

氧化石墨烯负载纳米零价铁(rGO-nZⅥ)去除地下水中Cr(Ⅵ)的XPS谱学表征

纳米铁广泛用于水中重金属离子的去除,但由于其易团聚的特性,在地下水中迁移性差,使其修复效果降低。氧化石墨烯具有吸附重金属的作用,但由于其表面带有负电荷,对带负电的高价铬(Cr_2O_7~(2-),CrO_4~(2-))吸附作用较弱。以氧化石墨烯(GO)为载体,采用液相还原法制备的氧化石墨烯负载纳米铁(rGO-nZⅥ),在改善纳米铁的分散性的同时,利用nZⅥ将带负电的高价铬(Cr_2O_7~(2-),CrO_4~(2-))还原为带正电的三价铬(Cr~(3+)),增强了氧化石墨烯对其吸附的性能。利用XRD和TEM对制备的rGO-nZⅥ进行表征,表明制备的rGO-nZⅥ近似球形,粒径为20~100nm;零价铁负载在GO表面。应用rGO-nZⅥ处理Cr(Ⅵ)污染的地下水,Cr(Ⅵ)的去除效率可达到100%,材料的最佳投加量与Cr(Ⅵ)浓度呈线性正相关。采用X光电子能谱(XPS)分析铬和铁的存在形态,并通过XPAPEAK41分峰后证实,Cr(Ⅵ)首先被还原为Cr(Ⅲ),进而生成Cr(OH)3吸附到材料表面。由XPS图看出,经24h反应,69.8%的Cr(Ⅵ)转化为Cr(Ⅲ)吸附到材料表面,此时仍具有Fe0的峰,证实材料具有很强的还原吸附铬的能力,且仍具有缓慢释放电子的能力,有利于后续长时间的修复。该结果对于利用rGO-nZⅥ处理地下水Cr(Ⅵ)污染具有重要的理论意义和实用价值。     

La0.3Sr0.7CrO3钙钛矿化合物高压合成和物性

 采用高压高温方法合成了单相的带宽调控型La_0.3Sr_0.7CrO₃ Mott化合物,对其晶体结构和磁学性质进行了研究。结果表明：La_0.3Sr_0.7CrO₃化合物具有立方钙钛矿晶体结构,温度在170 K以上其磁性为顺磁性,满足居里-外斯定律,温度低于20.7 K发生了自旋玻璃转变。     

FTIR和XPS对含低价Cr混合物物相分析的应用研究

因Cr的可变价态较多,且在制备低价Cr氧化物过程中,经常出现不同价态的中间体过渡产物,这些过渡产物的性质各异,往往对最终产物的形貌特征产生显著影响。以KCrO₂为原料制备低价Cr化合物的过程中出现了组成比较复杂的中间产物,为探讨反应机理并优化工艺流程,文章结合光电子能谱(XPS),傅里叶变换红外光谱(FTIR),X射线衍射(XRD),电感耦合等离子发射光谱(ICP-AES)元素分析和化学滴定分析对KCrO₂的还原中间产物进行了物相分析。XPS能谱分析表明, 还原中间产物中Cr元素是以三价形态存在的;对不同还原温度所得的中间产物的FTIR与其他方法所得的水合氧化Cr的FTIR进行比较, 并结合XRD测试,元素分析,化学分析结果可以得出下面结论：中间产物主要组成为Cr(OH)₃·nH₂O,CrOOH。还有少量的KOH或KCrO₂。在对中间物相分析的基础上, 对还原过程可能发生的反应进行了推测。     

Measurement of CrO in flames by cavity ringdown spectroscopy

CrO is an important intermediate in the high temperature oxidation chemistry of chromium containing species. This work reports the first detection of CrO in a flame. The B⁵-X⁵ electronic transition was probed by cavity ringdown spectroscopy (CRDS) in a lean (=0.38), low-pressure, flat, laminar hydrogen-oxygen-argon flame seeded with Cr(CO)₆. The previous B⁵-X⁵ CrO spectrum of Hocking et al. (605.0 nm-606.5 nm) is extended from the band head located at 605.6 nm to 614.4 nm. The temperature profiles of the doped and undoped flames were obtained from measurements of OH laser- induced fluorescence. Seeding the flame with Cr(CO)₆ increased the flame temperature by approximately 150 K. The concentration profile of CrO was measured as a function of height above the burner. CrO absorption signals were converted to concentration using the measured temperature profile and absorption cross-section calculated from lifetimes by Hedgecock et al. A lower limit peak CrO concentration of 1.6 ppb was found in the flame. Some uncertainty in the cross-section remains. Comparisons to calculations using STANJAN indicate that CrO is present in flames at super equilibrium concentrations. PACS 82.33.Vx; 42.62.Fi     

Alternating current surface photovoltage in thermally oxidized chromium-contaminated n-type silicon wafers

We investigated a variation of frequency-dependent alternating current (AC) surface photovoltages (SPVs) in thermally oxidized, chromium-contaminated, n-type silicon (Si) wafers. As previously reported, immediately after rinsing in Cr-contaminated solution, a Cr(OH)₃–Si contact causes a Schottky-barrier-type AC SPV on n-type Si. Upon oxidation at 373 K for 10 min, the Schottky barrier collapses and, with further oxidation, a metal-induced negative oxide charge, due to atomic bridging of (CrOSi)⁻ and/or CrO₂^-\mathrm{CrO}_{2}^{-} networks, definitely grows over time in SiO₂. For samples oxidized at temperatures between 823 and 1023 K for 30 min, the observed AC SPV gives evidence that the metal-induced negative oxide charge causes a strongly inverted state of the Si surface. At oxidation temperatures higher than 1023 K and /or for an oxidation time longer than 60 min, the level height of the AC SPV is reduced, implying that the strongly inverted state changes into a less depleted state, whilst, finally, the AC SPV disappears. In this case, the collapse of the (CrOSi)⁻ and/or CrO₂^-\mathrm{CrO}_{2}^{-} networks is anticipated, with a possible change into Cr₂O₃. The existence of the (CrOSi)⁻ and/or CrO₂^-\mathrm{CrO}_{2}^{-} networks has also been confirmed in p-type Si wafers.     

Chemical shifts of Cr Kα and Kβ1, 3 lines by WDXRF spectrometry

Chemical shift and full widths at half maximum (FWHM) intensity of chromium Kα and Kβ_{1, 3} lines were examined for 12 kinds of materials containing chromium (CH₃CO₂)₇Cr₃(OH)₂, CrK(SO₄)₂.12H₂O, Cr(NO3)₃.9H₂O, Cr₂O₃, CrF₂, CrF₃.4H₂O, CrCl₂, CrCl₃, CrCl₃.6H₂O, [CrCl₂(H₂O)₄]Cl.2H₂O, Cr₂(SO₄)₃.15H₂O, CrO and Cr metal by wavelength‐dispersive X‐ray fluorescence (WDXRF) spectrometry. The chemical shifts, asymmetry index and the half‐widths of both the X‐ray emission lines show interesting trends with the oxidation state of chromium. It was observed that the chemical shifts for F compounds are higher than Cl compounds. It was also found larger chemical shifts and FWHM for Kβ_{1, 3} lines than Kα ones. It should be noted that the magnitude of chemical shifts increases with increase in the number of ligand atoms. Copyright © 2009 John Wiley & Sons, Ltd.     

铬焚烧中CrO_3 H_2CrO_2 H_2O反应机理研究

本文从量子化学角度研究了在含铬物质焚烧的反应中CrO3 H2(?)CrO2 H2O反应机理。通过Gaussian 98软件计算,优化得到各反应物质的几何结构以及体系的内部反应路径,得出该反应体系为两步反应:首先由CrO3 H2经过一个过渡态生成中间体HCrO3 H,然后由中间体HCrO3 H经过一个过渡态生成CrO2 H2O。通过反应物和产物的活化能比较,得出该反应体系更易于正向反应发生。