共查询到20条相似文献，搜索用时 140 毫秒
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众多的研究已经表明,矿物的形貌是其成分、结构和生长环境的综合反映,对其进行研究可以获得晶体生长的地质条件等有关信息.矿物晶面的表面微形貌,对于晶体内部缺陷和生长环境的变迁反映非常敏感,它记录了晶体生长过程中更有价值的信息--界面的特性. 相似文献
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研究了不同添加剂对晶体生长的影响,对NaCl和K2SO4晶体在流化床中的动态生长行为及单个晶体在溶液中的静态生长行为进行了研究.实验中还考虑了晶体表面的完整程度对晶体生长的影响,并对上述晶体的生长机理进行了分析.此外,对存在添加剂及纯溶液中NaCl和K2SO4晶体的溶解过程进行了研究.结果表明,本实验所选用的添加剂在低浓度下即能有效抑制NaCl和K2SO4晶体生长. 相似文献
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Nd3+∶YAG晶体的研究始于1951年,13 a后由美国贝尔实验室首先用它研制成了激光器.自20世纪60年代发展以来,提拉法晶体生长研究取得了很大进展,主要经历两个阶段:70年代初,完成了对晶体生长条件的探索,基于固液界面有关研究成果,确立了(111)方向凸界面生长的基本模式,使钇铝石榴石(YAG)从实验室走向生产;80年代初期,大尺寸的钇铝石榴石晶体生长技术研究成功,提高了晶体质量和产量,降低了成本.近年来,采用提拉法生长Nd∶YAG晶体的工艺技术日趋成熟. 相似文献
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从晶体结构化学角度出发，分析了金的电子结构及性质、黄铁矿晶体结构特点、二氧化硅的电子结构特点和石英晶体表面特征；探讨了Au^＋和Au^－离子形式分别替代Fe^2 离子和S^2-离子的形成机理以及以可见金方式在黄铁矿中的赋存机制；认为金在黄铁矿中的富集主要与其晶体结构有关，特别是与黄铁矿中Fe-S，S-S，Au-S和Fe-Au键的电子结构特点有关；应用稳定配合物的18电子规则和晶体生长的界面相模型探讨了石英含金机理；研究表明，石英含金不仅与石英表面的结构、内部缺陷和表面特征有关，还与石英生长的环境有关，尤其是与石英表面键的电子结构特点有关，并主要受石英晶体生长过程中的界面相的控制。 相似文献
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原生煤岩组合体界面是非均质的且包含大量复杂的微观结构。为透明求解非均质煤岩界面导致的复杂物理场,采用工业CT对原生煤岩组合体试件进行了扫描试验,重构了原生煤岩组合体界面三维模型,计算了非均质煤岩界面的分形维数;基于此建立了原生煤岩组合体数值模拟模型,模拟分析了单轴压缩条件下原生煤岩组合体的应力及损伤特征,并通过煤岩组合体单轴压缩试验结果验证了数值模拟规律的可靠性。研究结果表明：原生煤岩组合体界面具有复杂的微观结构且具有分形特征,分形维数能够反映界面宏观形态;单轴压缩状态下,原生煤岩组合体中垂向应力呈非均匀分布,煤岩界面的存在会在煤体中派生水平压应力,在岩石中派生水平拉应力,煤岩界面附近水平应力呈拱形分布;原生煤岩组合体的损伤破坏主要发生在煤体中,煤体的损伤首先发生在远离界面的煤体中并逐渐向界面处扩展,界面分形维数与试件出现初始损伤对应的轴压呈正相关;由于煤岩界面压应力拱的存在导致原生煤岩组合体整体的强度高于煤体,破坏后的煤体呈拱形分布。预期研究结果对于煤岩动力灾害防治具有一定意义。 相似文献
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在今天,要想认识、了解金刚石晶体的生长过程,求得原子与分子级的微观情报,就必须对晶面上发育的生长层详加调查。这是因为晶体生长是在固相与液相的界面亦即晶面上进行的,在那里必然留下若干晶体生长的证据。 相似文献
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最近NGTC实验室检测出多批次CVD合成钻石,这些CVD合成钻石均具有明显的鉴定特征,使用钻石观测仪（DiamondViewTM）观察可见蓝色、橙红色荧光和蓝色磷光以及细密层状生长纹理,光致发光光谱中可见737 nm处的特征发光线.这些特征均与其生长结构及生长过程中进入钻石晶体中的杂质有关.笔者以最近检测过程中发现的一颗CVD合成钻石为例,使用高倍率显微技术对其层状结构的微细特征及其在钻石观测仪下的荧光特征的关系进行了详细观察和对比.结果显示,此样品与之前检测到的CVD合成钻石略有差异.此次检测到的样品在钻石观测仪（DiamondViewTM）下观察具有较宽的层状生长分区,层与层之间的分界线十分明显且在高倍显微镜下也可见到细微的生长特征.通过对样品特征的分析,了解了晶体生长过程中多阶段生长条件的变化,更直观的展现了CVD合成钻石的生长过程. 相似文献
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Catherine M. Corrigan Nancy L. Chabot William F. McDonough Sarah A. Saslow 《Geochimica et cosmochimica acta》2009,73(9):2674-6583
To better understand the partitioning behavior of elements during the formation and evolution of iron meteorites, two sets of experiments were conducted at 1 atm in the Fe-Ni-P system. The first set examined the effect of P on solid metal/liquid metal partitioning behavior of 22 elements, while the other set explored the effect of the crystal structures of body-centered cubic (α)- and face-centered cubic (γ)-solid Fe alloys on partitioning behavior. Overall, the effect of P on the partition coefficients for the majority of the elements was minimal. As, Au, Ga, Ge, Ir, Os, Pt, Re, and Sb showed slightly increasing partition coefficients with increasing P-content of the metallic liquid. Co, Cu, Pd, and Sn showed constant partition coefficients. Rh, Ru, W, and Mo showed phosphorophile (P-loving) tendencies. Parameterization models were applied to solid metal/liquid metal results for 12 elements. As, Au, Pt, and Re failed to match previous parameterization models, requiring the determination of separate parameters for the Fe-Ni-S and Fe-Ni-P systems.Experiments with coexisting α and γ Fe alloy solids produced partitioning ratios close to unity, indicating that an α versus γ Fe alloy crystal structure has only a minor influence on the partitioning behaviors of the trace element studied. A simple relationship between an element’s natural crystal structure and its α/γ partitioning ratio was not observed. If an iron meteorite crystallizes from a single metallic liquid that contains both S and P, the effect of P on the distribution of elements between the crystallizing solids and the residual liquid will be minor in comparison to the effect of S. This indicates that to a first order, fractional crystallization models of the Fe-Ni-S-P system that do not take into account P are appropriate for interpreting the evolution of iron meteorites if the effects of S are appropriately included in the effort. 相似文献
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James R. Rustad 《Contributions to Mineralogy and Petrology》2015,169(5):50
The interfacial contact region between a rhyolite melt and the accessory minerals monazite, xenotime, and zircon is investigated using molecular dynamics simulations. On all surfaces, major structural rearrangement extends about 1 nm into the melt from the interface. As evidenced by the structural perturbations in the ion distribution profiles, the affinity of the melt for the surface increases in going from monazite to xenotime to zircon. Alkali ions are enriched in the melt in contact with an inert wall, as well as at the mineral surfaces. Melt in contact with zircon has a particularly strong level of aluminum enrichment. In xenotime, the enrichment of aluminum is less than that in zircon, but still notable. In monazite, the aluminum enrichment in the contact layer is much less. It is expected that the relative surface energies of these accessory minerals will be a strong function of the aluminum content of the melt and that nucleation of zircon, in particular, would be easier for melts with higher aluminum concentration. The crystal growth rate for zircon is expected to be slower at a higher aluminum concentration because of the effectiveness of aluminum in solvating the zircon surface. The variable interfacial concentration profiles across the series of accessory minerals will likely affect the kinetics of trace element incorporation, as the trace elements must compete with the major elements for surface sites on the growing accessory minerals. 相似文献
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E.Bruce Watson 《Geochimica et cosmochimica acta》1996,60(24):5013-5020
Adsorption or enrichment of trace elements in the near-surface or interfacial regions of minerals has been documented in systems ranging from low-temperature aqueous environments to magmas. Under static conditions, this surface enrichment results from chemical equilibrium between the host medium of the crystal and the surface layer, which may exhibit diversity or flexibility in the types of atomic sites present. If the crystal is growing, any trace elements bound in the surface layer may be buried and trapped in the newly-formed lattice, resulting in lattice concentrations that deviate substantially from those predicted by equilibrium partitioning between the crystal and its growth medium. The effectiveness of this growth entrapment process depends upon the interplay between the growth rate, V, of the crystal (which can be thought of as the burial rate of surface-enriched element i) and the diffusivity, Di , in the near-surface region of the crystal (which determines how efficiently i can escape to the surface by diffusion). The competition can be quantified in terms of the dimensionless number Vl/Di; (termed the growth Péclet number, Pe), where l is the half-thickness of the surface-enriched layer. Depending upon the degree of surface enrichment, some growth entrapment is possible if Pe > 0.1, and the process is highly efficient if Pe > 10. An assessment of Pe for a wide variety of geological situations suggests that growth entrapment is common in diagenetic and metamorphic environments but limited to slow lattice diffusants in silicic igneous systems. It is probably rare to nonexistent in basaltic systems except at laboratory growth rates. 相似文献
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Silvio Mollo Valeria Misiti Piergiorgio Scarlato 《Central European Journal of Geosciences》2010,2(2):188-198
We experimentally investigate the major and trace elements behavior during the interaction between two partially molten crustal rocks (meta-anorthosite and metapelite) and a basaltic melt at 0.5–0.8 GPa. Results show that a hybrid melt is formed at the basalt-crust contact, where plagioclase crystallizes. This contact layer is enriched in trace elements which are incompatible with plagioclase crystals. Under these conditions, the trace element diffusion coefficients are one order of magnitude larger than those expected. Moreover, the HFSE diffusivity in the hybrid melt is surprisingly higher than the REE one. Such a feature is related to the plagioclase crystallization that changes the trace elements liquid-liquid partitioning (i.e. diffusivity) over a transient equilibrium that will persist as long as the crystal growth proceeds. These experiments suggests that the behaviour of the trace elements is strongly dependent on the crystallization at the magma-crust interface. Diffusive processes like those investigated can be invoked to explain some unusual chemical features of contaminated magmatic suites. 相似文献
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岩石在细观尺度上是由矿物颗粒胶结而成,除细观结构的力学特性外,其几何特征（颗粒界面网络结构和颗粒粒度分布）也对宏观断裂能具有一定的影响。为了探索这种几何特征与大理岩断裂能之间的相关性,从而进一步揭示岩石细观断裂机制,首先通过三点弯曲试验测定大理岩的断裂能,然后在试验后的三点弯试件断口处取岩石切片,进行电镜（SEM）扫描以获取岩石细观结构图像。利用图像处理技术获取岩石细观颗粒的界面网络图。通过对颗粒界面网络图分析,发现颗粒界面网络拓扑结构与颗粒粒度分布具有较强的分形特征。将二者分形维数与试件宏观断裂能相对比,发现它们之间具有很强的相关性。界面网络分形维数与宏观断裂能具有很强的二次相关性,而粒度分布维数与宏观断裂能之间具有较强的线性相关性。宏观断裂能随着两种分形维数的增大而增大。该研究结果揭示了宏观断裂能与岩石细观结构几何特征的相关性,加深了对宏观断裂能细观机制的理解。 相似文献
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R. Hellmann J.-M. Penisson R. L. Hervig J.-H. Thomassin M.-F. Abrioux 《Physics and Chemistry of Minerals》2003,30(4):192-197
Using an approach combining high-resolution and energy-filtered transmission electron microscopy (HRTEM and EFTEM), we have studied with Å to nm-spatial resolution the interfacial region that delimits the near-surface altered zone and non-altered labradorite feldspar after dissolution under acid pH conditions. The interface is characterized by extremely sharp and spatially coincident changes in structure and chemistry. The 500-nm-thick altered zone is depleted in interstitial cations (Ca, Na, K) and Al, a framework element, whereas it is enriched in H, O, and Si. Modeling H+-alkali interdiffusion within a 500-nm-thick altered zone shows that volume interdiffusion cannot reproduce the sharp chemical interfaces measured by EFTEM. Based on these new data, we propose that the near-surface altered zone is a result of interfacial dissolution-reprecipitation, and not of preferential leaching of cations and interdiffusion with H+. This implies an intrinsic dissolution process that is stoichiometric, where the breaking of bonds and release of interstitial cations and framework elements (Al, Si, and O) to solution occur contemporaneously at equal relative rates from the original fluid–mineral interface. 相似文献
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黄山第四纪泥砾沉积物分形结构特征与成因机制分析 总被引：2，自引：0，他引：2
黄山第四纪泥砾沉积物粒度组成的分维值介于２７０８～２７３５之间,非常接近古泥石流堆积物粒度组成的典型分维值２７５．结合沉积特征,表明该沉积物属第四纪间冰缘环境下的稀性泥石流沉积,其形成过程与季风型冰缘环境有关 相似文献
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Usually it is assumed that the partitioning of trace elements into titanite in metaluminous granitoid plutonic environments takes place under equilibrium conditions and that compositional zoning is due solely to progressive changes in melt chemistry and/or mineral/melt partition coefficients. Examination of titanites from a variety of Caledonian metaluminous granitoids and related rocks has revealed that sector zoning is present, indicating disequilibrium partitioning. The sector zoning in titanites is defined principally by the distribution of the rare earth elements (REE), Y, Nb, Al and Fe. The REE, Y and Nb preferentially occur within the minor (100) sectors relative to the morphologically important (111) sectors. The reverse is true of Al and Fe which preferentially occur within the (111) sectors relative to the (100) sectors. The patterns of sector zoning are complicated by the fact that the relative growth rates of the various crystal faces fluctuated during growth. Sector zoning indicates that crystal-interface kinetics are responsible for the observed patterns of element partitioning. It is concluded that differences in the lateral-layerspreading rates of crystal faces bring about the sector zoning. The results have implications for the use of trace element partition coefficients in the modelling of fractionation processes. 相似文献
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纤维加筋土中单根纤维的拉拔试验及临界加筋长度的确定 总被引：4，自引：1，他引：3
纤维加筋土物理力学性质主要受纤维与土界面之间作用力大小的控制,了解界面的微观力学行为对研究纤维加筋土的机制及工程应用具有重要意义。首先,利用自行设计的纤维拉拔试验装置,对不同含水率和不同干密度的土样进行了单根纤维的拉拔试验,测试并计算了单根纤维与土接触面之间的剪切强度和残余剪切强度,分析了含水率和干密度大小对它的影响。结果表明,设计的试验装置和试验方法能较好地进行单根纤维的拉拔试验,具有较高的准确性和精度。获得了纤维加筋土中界面剪切强度和残余强度与土样含水率和干密度之间的定量关系;分析拉力-位移曲线表明,加筋土中纤维的拉拔特性取决于筋土界面的力学行为,曲线的形状受含水率和干密度的影响不明显。最后,利用测得的筋土界面强度导出了纤维加筋的临界长度。 相似文献
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The structure and reactivity of the dolomite (104)-water interface was probed in situ with high resolution X-ray reflectivity and surface force microscopy at room temperature. Measurements in stoichiometric solutions alternating between saturated and supersaturated (log IAP/K = 2.3) conditions show that the dolomite surface termination readily changes in response to solution composition, but these changes are self-limiting and partially irreversible. The freshly cleaved dolomite (104) surface in contact with the saturated solution has a stoichiometric termination, a distinct surface hydration layer and small surface structural displacements, similar to those observed previously at the calcite-water interface. After reaction with supersaturated solutions dolomite is terminated by a two-layer thick Ca-rich film with substantial structural displacements of the cations. With subsequent exposure to a saturated solution this surface was transformed to an interfacial structure different from the freshly cleaved surface, having a reduced density of the outermost surface layer and a Ca-rich second layer. These results provide new insight into the lack of dolomite growth in modern carbonate environments (i.e., the “dolomite problem”), suggesting that this behavior is associated with a combination of thermodynamic and kinetic factors, including (1) growth of compositionally modified epitaxial CaXMg2−X(CO3)2 layers having thicknesses limited by lattice strain, (2) slow incorporation of Mg during layer growth, and (3) partial irreversibility of surface reactions. 相似文献