细菌纤维素的晶体结构

用扫描电镜观察了木醋杆菌1.1812在静态培养下生产的细菌纤维素的形态结构.用傅立叶红外光谱(FT-IR)、广角X射线衍射、交叉极化/魔角旋转固体核磁共振(CP/MAS13C NMR)分析细菌纤维素在干态下和湿态下的晶体结构.在干态下,细菌纤维素有较高的结晶指数和较高的纤维素L;而湿态下的细菌纤维素没有显示出纤维素I晶型的X射线衍射特征峰和核磁共振图谱,结晶指数和晶粒尺寸都相对较小.     

Crystal Structure during Film Formation

For evaporation-deposited Ti films, face-centred cubic structure was observed at the initial stage of film growth, then transited to the hexagonal close-packed structure during film growing (less than 50 nm thick). While. for ion-beam sputter-deposited films. the structure of films always kept the fcc structure during all stages of film formation. The structure of film at initial growth stages relates with the substrate. It is discussed that different film processes and different growth stages provide different thermodynamic condition of film formation and result in the different crystal structures of films during the film formation     

Crystal Structure of Ni5P2

It is shown by x-ray diffraction, energy-dispersive x-ray spectrometry, and electron probe microanalysis that, at 800°C, the Ni–P system contains four phosphides in the composition range 25–33 at % P: Ni₃P, Ni₅P₂, Ni₁₂P₅, and Ni₂P. The structure of Ni₅P₂ is determined by single-crystal x-ray diffraction: sp. gr. P3¯c1, new structure type, a = 0.6613(3) nm, c = 1.2311(6) nm, 347 independent hklreflections with F _hkl > 4(F _hkl), R _F = 0.0346. The key structural features of Ni₅P₂ are discussed.     

RDX晶体结构与性能研究进展

单质炸药的性能不仅受炸药分子结构的影响,而且与炸药晶体结构密切相关。综述了RDX晶体结构与性能方面的研究进展。RDX晶胞为斜方晶系,Pbea点群,a=13．182A,b=1I．574A,c=10．709A,Z=8,α=β=γ=90．0°。当平均颗粒直径在16．7—337．9μm范围时,RDX颗粒度对撞击感度影响较大,颗粒越大撞击感度越高。证实了RDX的晶体结构对其性能具有重要影响。因此,RDX在应用过程中应充分考虑其晶体结构。     

向列型热致液晶聚酰胺的结构表征

采用傅立叶红外光谱仪（IR）、广角X射线衍射仪（WAXD）、热台偏光显微镜（POM）及扫描电子显微镜（SEM）对所合成热致液晶聚酰胺进行了结构表征。IR谱图显示了该聚合物为半刚性结构,与所设计的分子结构相一致;WAXD曲线显示处于液晶态的聚合物在2θ=20°左右有一弥散的峰,表明该液晶聚合物为向列型液晶结构;POM观察...     

Crystal Structure of C60 and C70 Compounds

Abstract

Fullerene intercalated compounds are the most intensively examined molecular materials to exhibit superconducting, ferromagnetic, optical non-linear and other properties. the fullerene C₆₀ or C₇₀ serve usually as electron acceptors in these materials. Although the electron acceptor properties of the fullerene are similar to those of the weak organic acceptors, the fullerene forms various C₆₀-based materials, namely clathrates, charge-transfer complexes and weak, molecular complexes. the search for cation species for fullerene-based materials is one of the routes towards progress in the design of materials with interesting physical properties.

Physical properties of the fullerene-derived molecular compounds are determined mainly by their crystal structure packing. Relatively large cavities in the fullerene solid can easily accommodate small units like solvent molecules or electron-donor organic compounds. An intercalation with these species is usually accompanied either by a lowering in crystal symmetry or by a change in the stacking arrangement of the C₆₀ spheres. These factors influence the interactions between fullerene (host) and an organic molecule (guest). Charge transfer between the electron donor molecule and the fullerene is usually weak and is hindered by unfavourable steric factors; it does not correlate with the ionization potential of the donor.

In this paper we present characteristic structures of one-, two-, and three-component fullerene compounds or else the structures of fullerene clathrates, neutral (van der Waals) complexes and ionic charge-transfer complexes. One can conclude that the stability and properties of the fullerene-based derivatives are defined by the steric compatibility between the three-dimensional donor and the spherical or elongated fullerene.     

PET结晶形态对其微孔发泡材料泡孔结构的影响

以CO2为发泡剂,针对三种具有不同初始结晶形态的聚对苯二甲酸乙二醇酯(PET)原料进行间歇固态发泡的研究.结果表明,CO2的溶胀作用会导致PET晶片的显著增厚,而显著增厚的晶片会使微孔发泡材料的泡孔分布不均匀.但是对孔径和孔密度影响不大.调控PET的发泡条件制备泡孔.结构好的PIT微孔发泡材料方法之一是缩短溶胀时间,在...     

硒镓银晶体的结构与光学特性研究

用坩埚旋转下降法生长出 2 2mm× 88mm的红外非线性光学晶体硒镓银 ,并对其结构与光学特性进行了研究 ,测定出晶体结构为 4- 2m点群 ,晶格常数a =0 .5 993 3mm ,c =1.0 884nm ,熔点860℃ ,在 10 .6μm附近的透过率为 62 .4% ,对 10 .6μmCO2 激光的能量转换效率达 12 %。此外 ,还进行了扫描电子显微镜 (SEM )图像观察和核光谱特性测量。     

Structure of the XPS Spectra of a ThO2 Crystal Film

Radiochemistry - The complex structure of precision X-ray photoelectron spectra (XPS) of valence and core electrons of a ThO2(001) crystal film on Si(100) was obtained and analyzed, and the...     

Effect of Substrate Wettability and Surface Structure on Nucleation of Crystal

The heterogeneous nucleation behaviors of NH4Cl crystal on rough aluminum substrate surface immerged in NH4Cl-H2O solution were experimentally analyzed, and the influence mechanism of the micro/nano-scale surface structures on heterogeneous nucleation was investigated. It has been shown that wettability and nucleation are affected by substrate surface condition. The intrinsic wetting properties between nucleus and substrate surface, and the surface structure of certain geometrical scales, both impose effects on the heterogeneous nucleation properties. For a nucleus-wetting substrate surface, heterogeneous nucleation is promoted by a higher complexity of the surface morphology; but for a nucleus-nonwetting substrate surface, heterogeneous nucleation is inhibited by a higher complexity of the surface morphology.     

粉石英在行星球磨过程中的晶体结构的变化

论述了用行星球磨机对粉石英进行超细粉碎时所发生的晶体结构和物理化学方面的变化。采用粒度分析、扫描电镜、Ｘ－射线衍射、差热分析等测试手段,揭示了粉石英在球磨过程中晶体结构变化的特征,剖析了粉石英在球磨过程中呈现出的阶段性以及同步性的特点。并通过碱溶和水溶试验,验证了表面无定形层的形成     

Structure and Magnetism of the Composite Crystal Ca0.824CuO2

We have studied the magnetic state from a viewpoint of crystallographic features of the 1-D chain compound Ca_0.824CuO₂. A possible spin-hole arrangement in the magnetically coexisting state was determined by analyzing the local structural distortion in the CuO₂ chain by means of a modulated-crystal-structure analysis. The essential periodic sequence expected is (: up- and down-spin, : hole), which can be regarded as a kind of spin-1/2 ferromagnetic-antiferromagnetic alternating Heisenberg chain.     

Crystal Structure of (V,Mo)84P49

A new ternary compound of composition (V,Mo)₈₄P₄₉ (V_3.2Mo_8.8P₇) is synthesized, and its structure is determined by single-crystal x-ray diffraction: a new structure type, sp. gr. 6¯, a = 2.52015(3) nm, c = 0.330070(5) nm; R _F = 0.054, R _w = 0.058 for 1894 independent reflections with F _hkl > 4.0(F _hkl). V_3.2Mo_8.8P₇ is shown to contain mixed-occupancy (V, Mo) sites. The (V,Mo)₈₄P₄₉ and (Ti,Mo)₃₆P₂₁ structure types belong to a homologous series containing Cr₁₂P₇ as the n = 1 member.     

一种基于光子晶体结构的新型MEMS红外光源

结合光子晶体和表面等离子体共轭（surface plasmon resonance，SPR）技术，研究了一种新型的MEMS红外光源．相比传统的红外光源，该新型光源具有红外光谱窄、红外发射峰位置可调等优点．该光源衬底材料为硅，然后在硅表面形成SiO2-Cr-Au结构，并在Si-SiO2-Cr-Au结构表面形成刻蚀深度为2pm、孔间距分别为7μm和8μm（孔直径分别为3．5μm和4μm）等不同的周期性排列圆孔的光子晶体结构．采用有限元时域分析（finite-difference time-domain，FDTD）软件模拟和傅里叶红外光谱仪实际测量的结果表明，该新型MEMS红外光源具有窄的波峰，其反射光谱波谷波长和圆孔间距相近．通过理论推导和FDTD软件模拟，研究了光源光子晶体结构中圆孔深度和透射光谱波峰强度关系．结果表明，圆孔深度为2μm的结构比3μm结构的透射强度更强．透射强度与圆孔深度h在一定范围近似为倒数平方关系，即在一定范围内圆孔越深，透射越弱．     

Ti-V合金及其氢化物结构的研究

介绍了3种组成的Ti-V合金(Ti0.76V0.24、Ti0.51V0.49和Ti0.25V0.75)及其氢化物的晶体结构确定方法.通过XRD分析和理论计算,确定这3种合金为bcc结构,它们的纯β相氢化物是fcc结构,并测得了这两类结构的晶胞参数.研究发现,Ti-V合金吸氢性能比金属V有所改善,H原子数与合金原子数之和的比大于1.0才能发生α相氢化物向β相氢化物的转变.     

Ni掺杂ZnO晶体结构和红外光谱特性的研究

采用水热法制备了不同比例的Ni掺杂ZnO晶体.XRD和SEM结果表明,Ni掺杂浓度较低时,生成置换型氧化锌镍固溶体;当Ni掺杂浓度增加到5%时,Ni2+过饱和,析出部分斜方NiO.FT-IR发现样品在9001400cm-1之间出现了一个较宽的吸收带,且随Ni掺杂量的增加而加强,表现出良好的红外吸收特性.     

Co掺杂ZnO块材的晶体结构和磁性能研究

采用固相法制备了Zn1-xCoxO（x=0．05-0．25）块材,烧结温度和Co含量对Zn1-xCoxO（x=0．05-0．25）块材的晶体结构和室温磁性能影响强烈,当x≤0．1,烧结温度从800增加到1100℃时,Zn1-xCoxO（x=0．05-0．25）呈现出单相结构,但当x〉0．1,烧结温度为800℃时,样品中出现CoO相;随着烧结温度提高到900℃,样品再次获得纯的单相结构。为了获得高的饱和磁化强度Ms,最佳烧结温度应该根据Co含量进行调整。在最佳烧结温度条件下,当x从0．05提高到0．1时,Ms从0．79增加到了1．06μB/Co,但当x继续提高到0．2和0．25时,Ms分别降低到了0．59和0．41μB/Co。     

Data Import and Validation in the Inorganic Crystal Structure Database

In the following paper the input procedures for the Inorganic Crystal Structure Database (ICSD) will be outlined. The input flow of the data is explained. Since the data have been excerpted from journal articles a bibliometric analysis of the relevant literature is presented. The types of data and the form in which they are recorded are discussed. Finally, illustrations are given of the importance of data checking and the data checking procedures are described in detail.