化学复合镀Ni-P-SiO2镀层的XPS和AES分析

本文运用ＸＥＭ、ＡＥＳ和ＸＰＳ分析了Ｎｉ－Ｐ－ＳｉＯ２镀层的表面形貌及镀层组成。研究显示：Ｎｉ－Ｐ－ＳｉＯ２镀层表面光滑、均匀、光洁度好;其相对原子百分数为Ｎｉ７４．５６％,Ｐ１２．３８％,Ｓｉ２．７７％,Ｆｅ２．３２％,Ｏ６．６５％,镀层厚度为６．４０ｕｍ,镀层耐１０％ＮａＣｌ溶液和１％Ｈ２Ｓ气体的腐蚀能力较强。     

氯化钙—聚乙二醇配位聚合物的配位数研究

ＣａＣｌ２与ＰＥＧ在无水乙醇中发生反应制得的试样,以ＸＰＳ和ＩＲ测试的结果,表明该试样中存在Ｏ－Ｃａ配位键。通过溶液电导率的测量,发现１个Ｃａ＾２＋与ＰＥＧ４个链节单元的氧形成配位结构,又以电导率手段测得ＣｕＣｌ２－ＰＡＡｍ配位聚合物的配位数,其结果与利用Ｃｕ＾２＋２ｐＸＰＳ谱上的Ｓｈａｋｅ－ｕｐ效应研究所得该配位聚合物的配侠数一致,间接地验证以电导率手段测得ＣａＣｌ２－ＰＥＧ配侠聚合物配位数的可     

氧化态K—MoO3／γ—Al2O3催化剂结构的EXAFS研究

对Ｎａ２ＭｏＯ４．２Ｈ２Ｏ，ＭｏＯ３，（ＮＨ４）６Ｍｏ７Ｏ２４．４Ｈ２Ｏ等结构典型的含钼化合物及氧化态Ｋ－ＭｏＯ３／γ－Ａｌ２Ｏ３催化剂样品进行了ＥＸＡＦＳ测试，并以Ｎａ２ＭｏＯ４．２Ｈ２Ｏ为标样进行多层拟合计算，以研究各样品钼组分的配位结构。     

EXAFS研究负载型Ni／SiO2的区域结构

实验结果表明改进的实验室ＥＸＡＦＳ谱仪测试Ｎｉ箔的Ｋ吸收得到的ＥＸＡＦＳ谱与同步辐射上测量Ｎｉ箔得到的ＥＸＡＦＳ谱相近，利用实验室ＥＸＡＦＳ方法也可开展较好的结果测量研究，在ＳｉＯ２粉末载体上Ｎｉ负载量变化的ＥＸＡＦＳ结果表明，随着Ｎｉ负载量的降低，Ｎｉ的径向结构函数主配位峰的位置Ｒ＝０．２２０ｎｍ保持不变，但振幅强度逐渐降低。负载量从Ｎｉ箔到２．５％Ｎｉ／ＳｉＯ２，无序度因子σ由０．００６８ｎｍ     

MSC理论研究固体CS2的实验谱

用近边Ｘ射线吸收精细结构（ＮＥＸＡＦＳ）的多重用射集团（ＭＳＣ）方法对固体ＣＳ２的硫Ｋ－边ＮＥＸＡＦＳ实验谱进行了详细的研究，结果表明：１．确认Ｋ－边ＮＥＸＡＦＳ实验谱的主体结构是双σ键和π２．固体ＣＳ２中间时存在的硫的单键和双键和对应的两种吸收谱；３．π几乎全由双键所贡献，而双σ则分别由单键和双键所贡献；４．ＮＥＸＡＦＳ实验谱是两种吸收谱的叠加。     

［（μ－CF＿3CO＿2）＿2Ln（μ－CF＿3HCO＿2）Al（i－Bu）＿2·2THFl＿2（Ln＝Nd，Y）配合物的NMR和X－射线衍射研究

对［μ－ＣＦ＿３ＣＯ＿２）＿２Ｌｎ（μ－ＣＦ＿３ＨＣＯ＿２）Ａｌ（ｉ－Ｂｕ）＿２·ＴＨＦｌ＿２（Ｌｎ＝Ｎｄ，Ｙ）配合物单晶结构的Ｘ－射线分析指出，配合物具有中心对称性，配位中心由两个稀土和两个Ａｌ离子组成，稀土由两个ＴＨＦ和６个ＴＦＡ分子配位形成畸变的三盖三棱柱结构，Ａｌ由两个ＴＦＡＧ和两个ｉ－Ｂｕ配位形成四面体结构。桥连Ａｌ与两个稀土的ＴＦＡ分子的羧基发生歧化加氢，其碳原子由ＳＰ￣２型转变为ＳＰ￣３型．ＮＭＲ研究表明，在ＴＨＦ溶液中，该配合物保持了它在单晶中的配位结构，所不同的是两个ｉ－Ｂｕ在溶液中有两种异构形成，二者间为慢交换过程。     

透明莫来石陶瓷薄膜的光电子能谱研究

采用溶胶－凝胶工艺合成了莫来石透明陶瓷薄膜。用Ｘ射线光电子能谱分析技术，通过Ｏ１ｓＡｌ２ｐ太Ｓｉ２ｐ的Ｘ射线光电子能谱分析，探讨了透明膜的结构，组成及阳离子的配位形态。研究表明，干凝胶中铝以ＡｌＯ６八面体为主，硅为ＳｉＯ４四面体，随温度的升高ＡｌＯ６向ＡｌＯ４转化，引进透明膜结构的相应变化。     

晶化时间及硅源对SAPO—5分子筛的结构及模板剂状态的影响

通过改变硅源和晶化时间的方法，采用水热法合成了系列ＳＡＰＯ－５分子筛材料，用Ｘ光衍射（ＸＲＤ）和＾２７ＡｌＭＡＳ ＮＭＲ对产物的晶相结构进行表征，用＾１３Ｃ ＣＰ ＭＡＳ ＮＭＲ研究不同阶段的产物中模板剂的存在状态，结果可见：以ＳｉＯ２凝胶为硅源时，薄水铝石反应物有罗高的活性，在４８ｇ的晶化时间内，延长晶化时间有助于ＳＡＰＯ－５分子筛的完整结晶，当晶化时间超过４８ｈ时，其中已形成的ＳＡＰＯ－５的结     

X射线防护玻璃的结构效应

在Ｋ２Ｏ（Ｎａ２Ｏ）－ＰｂＯ（ＴｉＯ２）－ＳｉＯ２（Ａｌ２Ｏ３）系统中，防辐射玻璃是采用常规熔融方法制备的。该玻璃对Ｘ射线的防护能力可以用Ｃｏ６０－γ源检测。通过对玻璃的折射率、密度、显微硬度及线膨胀系数的测定研究，结果表明，玻璃的防Ｘ射线能力不仅取决于玻璃的密度及组分的质量吸收系数，而且与玻璃的结构特征有关。根据实验结果，我们提出了玻璃组成和结构对玻璃防Ｘ射线能力的综合效应的观点。玻璃结构紧密，能降低玻璃中高能粒子的运动速度，有利于玻璃对辐射粒子的吸收。我们将这种结构效应称为“韧滞效应”。     

Cu,Me—ZSM—5分子筛中共交换双阳离子的作用

研究了双阳离子共交换Ｃｕ，Ｍｅ－ＺＳＭ－５分子筛里第二种金属离子对ＮＯ催化分解的影响，并用ＸＲＤ、ＥＸＡＦＳ、和Ｏ２－ＴＰＤ－ＭＳ多种手段催化剂加以表征。分子筛中铜化学环境因为共交换阳离子的存在发生了明显变化，并对应于分子筛氧脱附性能的变化，这种变化因不同的阳离子而异：Ｍｇ＾２＋，Ｃｏ＾２＋等增强铜催化分解ＮＯ活性的共存阳离子使铜氧配位数增加，配位距离变大，从而使氧的脱附能力大幅度增强，而Ｋ＾＋Ｔ     

硅酸盐玻璃中的Na,Mg K-边XANES谱研究

本文利用同步辐射的NaK 边X 射线近边结构 (XANES)谱研究了含Na玻璃 (Na2 O SiO2 P2 O5和Na2 O SiO2 )的NaK 边的特征 ,同时建立了含磷 (P)的钠玻璃中NaK 边的能量 ,其能量位置随着P的含量增加 ,而增大其能量位置。CaMgSi2 O6(Di) NaAlSi3 O8(Ab)玻璃中MgK 边XANES的能量和Mg—O的键长有关系。在Di Ab玻璃中的Mg—O键距是 2± 0 0 4 。表明本方法可以作为研究含Mg玻璃的配位与局部结构新方法     

Effect of pressure on structure of oxide glasses at high pressure: Insights from solid-state NMR of quadrupolar nuclides

Revealing the structure of oxide glasses at high pressure remains a fundamental yet difficult problem in modern physical and chemical sciences. The recent advances in solid-state NMR techniques used for quadrupolar nuclides offer a considerably improved resolution of atomic sites, unveiling previously unknown structural details of oxides glasses at high pressure. Here, we present an overview of the recent progress and insights by high-resolution multi-nuclear triple quantum magic angle spinning (3QMAS) NMR into pressure-induced changes in coordination number, connectivity, and topological disorder in oxide glasses quenched from melts at high pressure. (11)B and (27)Al 3QMAS NMR studies of oxide glasses show that the formation of highly coordinated Al (([5,6])Al) and four coordinated ([4])B are prevalent at high pressure up to 8 GPa. The formation of oxygen clusters linking these highly coordinated framework units and Si (e.g., ([5,6])Al-O-([4])Si, ([5,6])Si-O-([4])Si, and Na-O-([5,6])Si) is observed in the (17)O NMR spectra at higher pressure, leading to an overall increase in the degree of polymerization with pressure. (23)Na MAS NMR spectra of diverse oxide glasses at high pressure and high magnetic field also indicate that the Na-O bond distance may decrease with pressure. Pressure-induced changes in structurally relevant NMR parameters such as the (17)O quadrupolar coupling product (P(q)) for the Si-O-Si cluster and (27)Al P(q) for Al sites in oxide glasses indicate the occurrence of pressure-induced reductions in the Si-O-Si angle and an increase in the Al-O bond length distribution with pressure, indicating an increase in the overall topological disorder in oxide glasses with pressure. All the pressure-induced changes in structure and topology are characterized by strong composition dependence. These experimental results highlight a new opportunity to investigate the molecular structures of silicate melts at high pressure and reveal connections between the microscopic signatures of anomalous and non-linear changes in the macroscopic properties of the corresponding liquids. While many challenges still remain in the synthesis of oxide glasses with wider range of melt composition at higher pressure above 12 GPa, recent progress in enhancement of sensitivity and resolution in the solid state NMR hold strong promise for study exploring additional details of connectivity among quadrupolar nuclides and medium-range order of the more complex, multi-components glasses at high pressure.     

Al coordination and water speciation in hydrous aluminosilicate glasses: direct evidence from high-resolution heteronuclear 1H-27Al correlation NMR

In order to shed light on the dissolution mechanisms of water in depolymerized aluminosilicate melts/glasses, a comprehensive one- (1D) and two-dimensional (2D) NMR study has been carried out on hydrous Ca- and Mg-aluminosilicate glasses of a haplobasaltic composition. The applied techniques include 1D 1H MAS NMR and 27Al-->1H cross-polarization (CP) MAS NMR, and 2D 1H NOESY and double-quantum (DQ) MAS NMR, 27Al triple-quantum (3Q) MAS NMR and 27Al-->1H heteronuclear correlation (HETCOR) and 3QMAS/HETCOR NMR. Ab initio calculations were also performed to place additional constraints on the 1H NMR characteristics of AlOH and Si(OH)Al groups. This study has revealed, for the first time, the presence of free OH (i.e. (Ca, Mg)OH), SiOH and AlOH species, in addition to molecular H2O, in hydrous glasses of a depolymerized aluminosilicate composition. The AlOH groups are mostly associated with four-coordinate Al, but some are associated with five- and six-coordinate Al.     

New opportunities for high-resolution solid-state NMR spectroscopy of oxide materials at 21.1- and 18.8-T fields

We present here high-resolution solid state NMR spectra of several oxide and silicate materials that illustrate the improvements obtainable with very high external fields (18.8 and 21.1 T), with probes capable of tuning to a wide frequency range that allow observations of nuclides from high to low magnetogyric ratio. We discuss 27Al MAS spectra for the zeolite scolecite (CaAl2Si3O10 x 3H2O), 17O MAS data for analcime (NaAlSi2O6 x H2O), calcium monoaluminate (CaAI2O4), and titanite (CaTiSiO5), 39K spin-echo spectra for leucite (KAlSi2O6), microline (KAlSiO8), muscovite (KAl2(AlSi3O10)(OH2) and a potassium aluminosolicate glass, and preliminary 73Ge spin-echo MAS spectra for crystalline and glassy germanium dioxide (GeO2).     

Raman and optical absorption spectroscopic investigation of Yb-Er codoped phosphate glasses containing SiO_2

Yb-Er codoped Na2O-Al2O3-P2O5-xSiO2 glasses containing 0 - 20 mol% SiO2 were prepared successfully. The addition of SiO2 to the phosphate glass not only lengthens the bond between pS＋ and non-bridging oxygen but also reduces the number of P=O bond. In contrast with silicate glass in which there is only four-fold coordinated Si4＋, most probably there coexist [SiO4] tetrahedron and [SiO6] oetahedron in our glasses. Within the range of 0 - 20 mol% SiO2 addition, the stimulated emission cross-section of Era＋ ion only decreases no more than 10%. The Judd-Ofelt intensity parameters of Er3＋, Ω2 does not change greatly, but Ω4 and Ω6 decrease obviously with increasing SiO2 addition, because the bond between Er3＋ and O2- is more strongly eovalently bonded.     

NMR Insights into Wasteforms for the Vitrification of High-Level Nuclear Waste

Magic-angle spinning nuclear magnetic resonance of ¹¹B, ²⁹Si and ²⁷Al has been used to study the distribution of nonbridging oxygen atoms (NBO) in an alkali borosilicate glass to which surrogate oxides for high-level radioactive waste have been added. The properties of such glasses are shown to depend on the fraction N ₄ of four-coordinated boron atoms (B4) and on the fraction of silicate tetrahedra possessing one NBO, Q³. The aqueous corrosion rate increases with Q³ content, as does weight loss due to evaporation from the melt. The activation energy for direct current conduction scales with N ₄. Values of N ₄ obtained for these glasses deviate from those predicted by the currently accepted model and are strongly affected by the modifier or intermediate nature of the surrogate oxide and also by its effect on the distribution of NBO between the silicate and borate polyhedra. Authors' address: Diane Holland, Department of Physics, University of Warwick, Coventry CV4 7AL, UK     

Electrical conductivity and tracer diffusion in sodium germanate glasses

Measurements of the electrical conductivity using ac complex impedance techniques and the tracer diffusion coefficient of ²²Na have been performed in a series of (x)Na₂O(1?x) GeO₂ glasses (where 0.0006 ? x ? 0.156). The compositional form of the Haven ratios, calculated from these data, have been interpreted in terms of a single defect model which considers a number of distinctly different jump frequencies for the alkali ion; the magnitude of these different jump frequencies is determined by the proximity of the diffusing alkali ion to a charge-compensating center within the glass network. Attractive interactions between the positive alkali ions and the negative charge-compensating centers cause successive jump directions of the alkali ions to become correlated. In the sodium germanate glasses the negatively-charged centers probably correspond to the six-fold coordinated sites formed upon addition of alkali oxide to GeO₂. These negatively-charged trapping centers correspond to non-bridging oxygen sites in alkali silicate glasses.     

Modifier cation (Ba,Ca, La,Y) field strength effects on aluminum and boron coordination in aluminoborosilicate glasses: the roles of fictive temperature and boron content

The field strength of modifier cations has long been known to have important effects on oxide glass properties, but effects on network structure can be complex. For two series of barium, calcium, lanthanum and yttrium aluminoborosilicates with two different B/Si ratios, we report systematic variations in boron and aluminum coordination determined by NMR, and glass transition and heat capacities from differential scanning calorimetry. Data on glasses with different fictive temperatures allow B and Al speciation to be compared on an isothermal basis, rather than as conventionally done for as-quenched structures. Temperature and compositional effects can thus be isolated. These data and comparison to previous studies on glasses with lower B/Si ratios clearly show that higher modifier cation field strength increases the fraction of five- and six-coordinated Al in all compositions. In contrast, the previously documented trend towards more three-coordinated boron (and hence more non-bridging oxygens, NBO) in low B/Si glasses with higher field strength cations reverses in high B/Si and in high NBO compositions. Al and B coordination numbers both decrease with higher fictive temperature in the glasses studied here, suggesting a simple mechanism of coupled structural change.     

阳离子对硅酸盐玻璃激光拉曼光谱影响的研究

运用拉曼光谱技术研究了Na2O(K2O)—CaO(MgO)—SiO2,Na2O(K2O)—Al2O3—SiO2,Na2O(K2O)—B2O3—SiO2,Na2O(K2O)—PbO—SiO2和PbO—BaO—SiO2五个系统的玻璃。结果表明,阳离子对玻璃近程结构的改造会引起拉曼特征的变化。部分样品是根据古玻璃平均成分在实验室烧制的,这项研究对于运用激光拉曼光谱区分不同系统的古代硅酸盐玻璃有重要意义。