缺陷化学在新材料研究中的作用     

陈泉水  郑举功  罗太安 《华东地质学院学报》2007,30(1):64-66

简述了缺陷的类型及其在新材料制备中的作用,通过实例分析固溶体和非化学计量化合物缺陷对材料物理化学性能的影响,阐明缺陷化学是一种研究新型功能材料的有力手段,根据新材料的发展趋势分析了缺陷化学可能取得的重大突破及新的研究热点。  相似文献   

古玉器的化学风化机理初探之二——块状模拟实验     

王荣 冯敏金普军  毛振伟王昌燧 《岩石矿物学杂志》2007,26(3):275-279

在前文粉末态模拟实验基础上,初步模拟古玉埋藏的酸性以及碱性环境,通过对不同材质玉料的块状形态在酸、碱缓冲溶液中的浸泡实验,并与粉末态玉料的浸泡结果进行对比分析,以深化对古玉器风化机理的认识。  相似文献   

Evidence for kinks in structural and thermodynamic properties across the forsterite–fayalite binary from thin-film IR absorption spectra     

A. M. Hofmeister  K. M. Pitman 《Physics and Chemistry of Minerals》2007,34(5):319-333

Infrared absorbance spectra over ∼100 to 1,800 cm⁻¹ were collected from optically thin films of 21 samples with compositions spanning the forsterite–fayalite binary. Polarization information from previous specular reflectance data on end-members was used in tracing the peaks across the entire binary. Peak positions (ν_i) were constrained by Lorentzian decompositions. Fitting also constrained widths for singlet peaks but for doublets and triplets, variation in ν_i with composition among the constituent polarizations alters widths from intrinsic. Because film thicknesses of 0.6–1.4 μm were estimated, our band strengths are approximate; however, relative intensities should be correct. Only for a few peaks does ν_i vary smoothly across the entire binary; instead, distinct linear trends exist for Fe- and Mg-rich olivines. Discontinuities and kinks in ν_i(X) occur at X = Mg/(Fe + Mg) = 0.7 and are accompanied by a change in intensity patterns. This interesting behavior was not revealed in previous spectra of powder dispersions. The contrasting character of IR vibrations for Fe- and Mg-rich olivines is inferred to arise from structural variations because (1) frequency is related to bond length, (2) other factors affecting frequency (cation mass and probably bonding type) vary linearly across the binary, and (3) available data on unit cell parameters are consistent with distinct trends for forsterites and fayalites. Vibrational components of heat capacity (C _V) and enthalpy (H) calculated from ν_i, were found to be slightly more negative than linear interpolations between values for forsterite and fayalite. Our computations give smaller negative excesses from ideality in H than do previous calorimetric measurements, but are equal within experimental uncertainties.  相似文献   

Effects of orientation on the diffusive properties of fluid-filled grain boundaries during pressure solution     

R. van Noort  C. J. Spiers  C. J. Peach 《Physics and Chemistry of Minerals》2007,34(2):95-112

An unresolved issue in the study of pressure solution in rock materials is the dependence of grain boundary structure and diffusive properties on the mutual orientation of neighbouring grain lattices. We report electrical measurements yielding the diffusivity of differently oriented halite–glass and halite–halite contacts loaded in the presence of brine. The halite–glass contact experiments show pressure solution of the halite and an effect of halite lattice orientation on grain boundary transport. Post-mortem observations show an orientation-dependent grain boundary texture controlled by the periodic bond chains in the halite structure. It is inferred that this texture determines the internal grain boundary structure and properties during pressure solution. In the halite–halite experiments neck-growth occurred, its rate depending on twist-misorientation. The results imply that deformation by pressure solution may lead to lattice-preferred orientation development, and that polymineralic rocks may deform faster at lower stresses than monomineralic rocks.  相似文献   

Thermodynamics of mixing in diopside–jadeite,CaMgSi<Subscript>2</Subscript>O<Subscript>6</Subscript>–NaAlSi<Subscript>2</Subscript>O<Subscript>6</Subscript>, solid solution from static lattice energy calculations     

Victor L. Vinograd  Julian D. Gale  Björn Winkler 《Physics and Chemistry of Minerals》2007,34(10):713-725

Static lattice energy calculations (SLEC), based on empirical interatomic potentials, have been performed for a set of 800 different structures in a 2 × 2 × 4 supercell of C2/c diopside with compositions between diopside and jadeite, and with different states of order of the exchangeable Na/Ca and Mg/Al cations. Excess static energies of these structures have been cluster expanded in a basis set of 37 pair-interaction parameters. These parameters have been used to constrain Monte Carlo simulations of temperature-dependent properties in the range of 273–2,023 K and to calculate a temperature–composition phase diagram. The simulations predict the order–disorder transition in omphacite at 1,150 ± 20°C in good agreement with the experimental data of Carpenter (Mineral Petrol 78:433–440, 1981). The stronger ordering of Mg/Al within the M1 site than of Ca/Na in the M2 site is attributed to the shorter M1–M1 nearest-neighbor distance, and, consequently, the stronger ordering force. The comparison of the simulated relationship between the order parameters corresponding to M1 and M2 sites with the X-ray refinement data on natural omphacites (Boffa Ballaran et al. in Am Mineral 83:419–433, 1998) suggests that the cation ordering becomes kinetically ineffective at about 600°C.  相似文献   

大别造山带毛屋超镁铁岩的铂族元素研究   总被引：1，自引：1，他引：1       下载免费PDF全文

刘 庆侯泉林  周新华谢烈文倪善芹  武昱东 《中国地质》2007,34(5):808-814

采用镍锍火试金法结合ICP-MS分析了毛屋斜方辉石岩和石榴二辉岩样品中的Ir、Ru、Rh、Pt和Pd的含量,结果显示其铂族元素(PGE)的含量随岩石类型无规律性的变化,原始地幔标准化后的铂族元素分布模式呈负斜率,Pd、Ir发生了分异。毛屋超镁铁岩铂族元素特征的形成受岩石中铂族元素的存在相制约,PPGE富集在富Cu硫化物,而IPGE以类似残留相、不熔的单硫化物固熔体形式存在,其中地壳混染也起了一定的作用;同时,成岩过程中流体的存在造成了Pt和Pd的活化。因此,单硫化物固熔体和流体的共同作用形成了毛屋超镁铁岩类似残留地幔岩的铂族元素分布特征。  相似文献   

GEO导航卫星定轨观测模型     

唐波  张军  陈刘成 《测绘学院学报》2007,(5)

根据GEO导航卫星的轨道特性,给出了严密的伪距观测和载波相位观测数学模型;讨论了其轨道和星钟差的解算条件,以及多星组差定轨的可行性。结果表明:在利用伪距时,如果测站钟差已知,需要4个以上站的数据才能进行定轨和星钟解算;如果站钟、星钟钟差已知,需要3个以上站的数据才能确定轨道。在利用站间组差伪距时,须有4个以上测站的钟差信息才能进行轨道和星钟解算;利用GEO卫星与MEO(IGSO)卫星组差定轨时,需要GEO卫星钟差已知且有3组星间组差数据。利用GEO卫星载波相位观测资料,不能单独解算轨道。  相似文献   

利用矢栅混合数据模式解决WebGIS技术难题——浏览器调阅空间数据速度问题     

李玉祥  王红 《测绘科学》2007,32(Z1):28-30

空间数据库是比一般的数据库要复杂,尤其在WebGIS中更是如此。因为网络传输和带宽的限制,因此如何有效地进行空间数据的调度和显示就成为WebGIS的技术难点。通过构造矢量和栅格混合WebGIS系统数据结构,并在服务端和客户端建立各自的多级缓冲,采用多线程调度方法,解决一直影响WebGIS系统运行速度瓶颈即网络带宽所带来WebGIS运行速度慢问题,提高WebGIS软件调阅空间数据的调度速度,加快页面响应时间。试验表明,利用矢栅混合数据模式能够有效提高WebGIS系统的空间数据调阅速度。  相似文献   

一种GNSS网络RTK改进的综合误差内插方法   总被引：2，自引：1，他引：2  

唐卫明  刘经南  刘晖  白清波 《武汉大学学报(信息科学版)》2007,32(12):1156-1159

在全球导航卫星系统（GNSS）网络RTK综合误差内插法（CBI）的基础上，提出了一种改进的综合误差内插方法（MCBI）。该方法把综合误差分为对流层模型改正、一阶电离层影响和除一阶电离层影响外的其他综合影响3个部分。实例证明了该方法不仅在精度上比综舍误差内插法要高，而且更利于流动站的应用。  相似文献   

Site-specific response spectra from the combination of microzonation with probabilistic seismic hazard assessment—An example for the Cologne (Germany) area     

Stefano Parolai  Gottfried Grünthal  Rutger Wahlstrm 《Soil Dynamics and Earthquake Engineering》2007,27(1):49-59

Seismic noise was measured at some 20 sites in the Cologne area (Germany) aligned nearly perpendicular to a graben structure. The H/V spectral noise ratio for each site was used to derive realistic S-wave velocity profiles down to the bedrock by means of a genetic algorithm inversion. Numerical simulations were performed for different combinations of source and propagation path parameters: focal depth, epicentral distance, attenuation and fault mechanism. Synthetic seismograms were produced and converted to Fourier and response spectra. Finally, the site-specific values from response spectral ratios, with their uncertainties, were used to modify attenuation functions entering the logic-tree algorithm of the probabilistic seismic hazard assessment (PSHA). The site-specific response spectra show the significance of taking into account the local S-wave velocity structure in PSHA.  相似文献