X射线荧光光谱法测定铬铁矿中主次量组分

采用低熔点的混合熔剂熔融制样,用３０８０Ｅ２型Ｘ射线荧光光谱仪对铬铁中Ｎａ,Ｍｇ,Ａｌ,Ｓｉ,Ｐ,Ｓ,Ｋ,Ｃａ,Ｔｉ,Ｃｒ,Ｍｎ,Ｆｅ和Ｎｉ等１３种主,次量元素进行测定,使用理论α系数校正元素间的吸收－增强效应,其分析结果有较高的准确度。     

关于偏岭石的X射线分析等问题──兼评何宏平等《天然烧变高岭石的研究》一文

偏岭石及其有关的变高岭石过去用五般鉴定结晶矿物的Ｘ射线衍射分析定为“非晶质”矿物；后来刘长龄用Ｘ射线衍射分析末照相高功率长时间拍照，见到有中，低强度的衍射条４．４－４．１，等多条；４．４Ａ及２．２Ａ等，二者有区别射线衍射仪强度曲线分析也有不同，而均属于准晶质或半晶质。     

硅灰石矿物发光材料的人工合成研究

对硅灰石矿物发光材料进行了人工合成研究，在合成试样中，分别掺入少量Ｅｕ＾３＋，Ｇｄ＾３＋，Ｐｂ＾２＋，Ｍｎ＾２＋等激活剂，于１０００℃或１１８０℃条件下分别通入Ｈ２Ｓ（ｇ），Ｈ２Ｏ（ｇ）以及用ＮＨ３，Ｈ２Ｏ吸收ＣＯ２（ｇ）等方法进行合成低温ＴＣ型三斜硅灰石和高温型假硅灰石，合成产物通过扫描电镜、Ｘ射线衍射和红外光谱实验，对合成过程中温度高低，时间长短、冷却快慢、降低温度合成高温型假硅灰石的方法进行     

第十四届国际X射线光学及显微分析会议纪要

第十四届国际Ｘ射线光学及显微分析会议纪要第１４届国际Ｘ射线光学及显微分析会议（ＸＩＶＩＣＸＯＭ）于１９９５年８月２９日至９月２日在广州举行。ＸＩＶＩＣＸＯＭ得到国家自然科学基金委员会和中国科学院南南合作基金资助，由广东省政府、中国科学院广州分院、广东...     

天然矿物Wadsleyite在我国首次发现

对于在毫县陨石中发现的Ｘ矿物，本文用电子探针获得了其化学成分：ＳｉＯ４，用Ｘ射线微区衍射得到了其结构参数。该矿物属斜方晶系，晶胞参数ａ＝０．８２６４，ｂ＝１．１４４８，ｃ＝０．５７０４ｎｍ。这些结果证明了它是Ｗａｄｓｌｅｙｉｔｅ，是橄榄石的高压相－β－（Ｍｇ，Ｆｅ）２ＳｉＯ４由冲击变质作用形成的。该矿物呈包裹体产出，在我国属首次发现。     

粘土矿物的X射线定量研究

Ｘ射线行射分析中，强度对比法是目前粘土矿物定量分析比较好的一种方法，其原理为矿物含量越高，它的衍射峰强度越强．但矿物衍射峰强度除与含量有关外，还与其他因素如结晶度、化学成分等有一定关系。因而，同种粘土矿物不同地区的样品，通常不具备同样的Ｘ射线衍射能力，如果用固定的比例系数进行定量分析，必然会影响其精度．本文作者用不同地区所产的粘土矿物进行定量试验，得出一系列强度比例系数（即权重系数），该系数与Ｂｌｉｓｃａｙｅ等人提出的固定比例系数相比，提高了定量分析精度．     

陨石熔壳研究

本文通过对毫县陨石熔壳的化学成分分析,Ｘ射线物相分析和红外光谱分析,并与一岩相互对照,讨论了熔壳中Ｆｅ的氧化状态的变化、击变玻璃及主要矿物结构参数的变化;研究了熔壳的氧化作用、击变作用、击变作用下矿物的变形机制,同时,熔壳的ＳＥＭ显微 貌像给出了熔壳的一套完整剖面,从而讨论了熔壳的烧蚀作用主要有破碎作用,熔融作用和抽蚀作用三种方式。此外,透射电观察敢证实了陨石熔壳中石英玻璃的存在。     

1∶20万岩石化探测量碳酸盐岩分析方法研究——等离子体质谱为主的配套分析方法

研究了碳酸盐岩中基体元素Ｃａ和Ｍｇ对测定痕量元素的影响及消除办法，建立了用等离子体质谱法测定碳酸盐岩石中２６个痕量元素的３个分析流程；并采用Ｘ射线荧光光谱、石墨炉原子吸收光谱、原子荧光光谱等方法配套测定了碳酸盐岩石中１５种主、次量元素。配套方法的检出限、精密度、准确度均符合１∶２０万岩石化探测量碳酸盐岩分析技术指标要求。方法经标样及碳酸盐岩石样品分析验证，其结果与不同实验室、不同方法测定结果相符。     

单向聚束质子激发X射线研究超导材料合成中的重力效应

采用质子激发Ｘ射线（ＰＩＸＥ）分析技术,以能量为２．０ＭｅＶ的质子束为激发源,利用单元四极磁透镜对带电粒子束的单向聚束本领,对超导材料样品ＣａＳｒ２Ｂｉ２Ｃｕ２Ｏ８进行了扫描ＰＩＸＥ分析,获得了其中元素Ｘ射线强度的垂向分布数据。在没有质子数数据参数的情况下,针对这种样品组成已知的特殊性,采用了内标迭代定量分析方法,获得了各元素的垂向浓度分布结果。强度和浓度数据均表明,元素Ｃａ主要分布在样品的顶部表层,证明人们关于超导材料合成过程中存在重力效应影响的推断是正确的。     

东南极拉斯曼丘陵柱晶紫苏堇青麻粒岩中堇青石的矿物学特征

东南极拉斯曼丘陵晚元古代（１０００Ｍａ）高级变质杂岩中区域性产出一套粗粒柱晶紫苏堇青麻粒岩，其原岩为含硼的富镁铝泥质岩。岩石中结晶粗大的堇青石在矿物化学成分上属于镁堇青石，其成分显示不均匀且具较明显成分环带的特征，从核部到边缘，其ＸＭｇ（Ｍｇ／Ｍｇ＋Ｆｅ２＋）比值由０．８５５变化为０．８１６。温压计算结果表明，所研究堇青石形成的Ｐ－Ｔ条件约为０．７６～０．７２ＧＰａ和８６０℃～８３０℃（核部至边缘）。Ｘ－射线粉晶结构分析证明这种堇青石属于低位结构状态的堇青石，晶体结构扭曲指数Δ＝０．２８～０．３０，在自然界比较少见。实验室合成的低位结构状态的堇青石只在持续较长时间的１３００℃～１４００℃的高温条件下稳定存在。因此，这意味着低位堇青石可能是由很高温变质作用及缓慢冷却的条件下结晶形成，这对于研究该区的地壳演化具有极其重要的意义。     

Dolomite effect on borosilicate glass alteration

Dolomite (CaMg(CO₃)₂) is one of the common rock-forming minerals in many geological media, in particular in clayey layers that are currently considered as potential host formations for a deep radioactive waste disposal facility. Magnesium in solution is one of the elements known to potentially enhance the alteration of nuclear glasses. The alteration of borosilicate glasses with dolomite as a Mg-bearing mineral source was investigated for 8 months in batch tests at 90 °C. Glass composition effects were investigated through two compositions (SiBNaAlCaZrO and SiBNaAlZrO) differing in their Ca content. The Ca-rich glass alteration is slightly enhanced in the presence of dolomite compared to the alteration observed in pure water. This greater alteration is explained by the precipitation of Mg silicate phases on the dolomite and glass surfaces. In contrast, the Ca-free glass alteration decreases in the presence of dolomite compared to the alteration observed in pure water. This behavior is explained by Ca incorporation in the amorphous layer (formed during glass alteration) coming from dolomite dissolution. Calcium acts as a layer reorganizer and limits glass alteration by reducing the diffusion of reactive species through the altered layer. Modeling was performed using the GRAAL model implemented within the CHESS/HYTEC geochemical code to discriminate and interpret the mechanisms involved in glass/dolomite interactions. Magnesium released by dolomite dissolution reacts with silica provided by glass alteration to form Mg silicates. This reaction leads to a pH decrease. The main mechanism controlling glass alteration is the ability of dolomite to dissolve. During the experiment the quantities of secondary phases formed were very small, but for longer time scales, this mechanism could supply sufficient Mg in solution to form large amounts of Mg silicates and sustain glass alteration. The ability of the GRAAL model to reproduce the concentrations of elements in solution and solid phases regardless of the amount of dolomite and the glass composition strongly supports the basic modeling hypothesis.     

Dissolution kinetics of a lunar glass simulant at 25 degrees C: the effect of pH and organic acids

The dissolution kinetics of a simulated lunar glass were examined at pH 3, 5, and 7. Additionally, the pH 7 experiments were conducted in the presence of citric and oxalic acid at concentrations of 2 and 20 mM. The organic acids were buffered at pH 7 to examine the effect of each molecule in their dissociated form. At pH 3, 5, and 7, the dissolution of the synthetic lunar glass was observed to proceed via a two-stage process. The first stage involved the parabolic release of Ca, Mg, Al, and Fe, and the linear release of Si. Dissolution was incongruent, creating a leached layer rich in Si and Ti which was verified by transmission electron microscopy (TEM). During the second stage the release of Ca, Mg, Al, and Fe was linear. A coupled diffusion/surface dissolution model was proposed for dissolution of the simulated lunar glass at pH 3, 5, and 7. During the first stage the initial release of mobile cations (i.e., Ca, Mg, Al, Fe) was limited by diffusion through the surface leached layer of the glass (parabolic release), while Si release was controlled by the hydrolysis of the Si-O-Al bonds at the glass surface (linear release). As dissolution continued, the mobile cations diffused from greater depths within the glass surface. A steady-state was then reached where the diffusion rate across the increased path lengths equalled the Si release rate from the surface. In the presence of the organic acids, the dissolution of the synthetic lunar glass proceeded by a one stage process. The release of Ca, Mg, Al, and Fe followed a parabolic relationship, while the release of Si was linear. The relative reactivity of the organic acids used in the experiments was citrate > oxalate. A thinner leached layer rich in Si/Ti, as compared to the pH experiments, was observed using TEM. Rate data suggest that the chemisorption of the organic anion to the surface silanol groups was responsible for enhanced dissolution in the presence of the organic acids. It is proposed that the increased rate of Si release is responsible for the one stage parabolic release of mobile cations and the relatively thin leached layer compared to experiments at pH 3 and 5.     

Phthalic acid complexation and the dissolution of forsteritic glass studied via in situ FTIR and X-ray scattering

Multiple Internal Reflection Fourier Transform Infra-Red (MIR-FTIR) spectroscopy was developed and used for in situ flow-through experiments designed to study the process of organic acid promoted silicate dissolution. In tandem with the FTIR analysis, ex situ X-ray scattering was used to perform detailed analyses of the changes in the surface structure and chemistry resulting from the dissolution process. Phthalic acid and forsteritic glass that had been Chemically Vapour Deposited (CVD) onto an internal reflection element were used as reactants, and the MIR-FTIR results showed that phthalic acid may promote dissolution by directly binding to exposed Mg metal ion centers on the solid surface. Integrated infrared absorption intensity as a function of time shows that phthalic acid attachment apparently follows a t^1/2 dependence, indicating that attachment is a diffusive process. The diffusion coefficient of phthalic acid was estimated to be approximately 7 × 10⁻⁶ cm² s⁻¹ in the solution near the interface with the glass. Shifts in the infrared absorption structure of the phthalate complexed with the surface compared to the solute species indicate that phthalate forms a seven-membered ring chelate complex. This bidentate complex efficiently depletes Mg from the glass surface, such that after reaction as much as 95% of the Mg may be removed. Surface depletion in Mg causes adsorbate density to fall after an initial attachment stage for the organic ligand. In addition, the infrared analysis shows that silica in the near surface polymerizes after Mg removal, presumably to maintain charge balance. X-ray reflectivity shows that the dissolution rate of forsteritic glass at pH 4 based on Mg removal in such flow-through experiments was equal to 4 × 10⁻¹² mol cm⁻² s⁻¹ (geometric surface area normalized). Reflectivity also shows how the surface mass density decreases during reaction from 2.64 g cm⁻³ to 2.2 g cm⁻³, consistent with preferential loss of Mg from the surface. Auxiliary batch experiments with forsteritic glass films deposited onto soda glass were also completed to add further constraints to the mechanism of reaction. By combining reflectivity with diffuse scatter measurements it is shown that the primary interface changes little in terms of atomic-scale roughness even after removal of several hundred angstroms of material. These measurements unequivocally show how a dicarboxylic acid bonds to and may chelate the dissolution of a magnesium-bearing silicate. At the molecular level the solid surface retreat may best be described by a depinning model where Mg is preferentially removed and residual silica tetrahedra polymerize and act to episodically “pin” the surface.     

仿碧玉玻璃制品的特征和鉴别

采用常规宝石学测试手段、薄片观察、电子探针、红外光谱等方法对目前中国市场上常见的一种仿碧玉玻璃样品进行了研究。结果表明,该样品为乳浊的脱玻化玻璃,其主要成分为SiO2,其次为Al2O3,还含有K,Na,Ca,Mg碱金属氧化物以及乳浊剂的析出物氟化钙和磷酸钙。该仿碧玉玻璃样品的鉴别特征为：颜色呆板,有时可见白斑,密度与硬度较低,贝壳状断口,羊齿植物叶脉状结构。此外,还可通过特征的红外光谱加以鉴别。     

The behaviour of Li and Mg isotopes during primary phase dissolution and secondary mineral formation in basalt

This study presents lithium (Li) and magnesium (Mg) isotope data from experiments designed to assess the effects of dissolution of primary phases and the formation of secondary minerals during the weathering of basalt. Basalt glass and olivine dissolution experiments were performed in mixed through-flow reactors under controlled equilibrium conditions, at low pH (2-4) in order to keep solutions undersaturated (i.e. far-from equilibrium) and inhibit the formation of secondary minerals. Combined dissolution-precipitation experiments were performed at high pH (10 and 11) increasing the saturation state of the solutions (moving the system closer to equilibrium) and thereby promoting the formation of secondary minerals.At conditions far from equilibrium saturation state modelling and solution stoichiometry suggest that little secondary mineral formation has occurred. This is supported by the similarity of the dissolution rates of basalt glass and olivine obtained here compared to those of previous experiments. The δ⁷Li isotope composition of the experimental solution is indistinguishable from that of the initial basalt glass or olivine indicating that little fractionation has occurred. In contrast, the same experimental solutions have light Mg isotope compositions relative to the primary phases, and the solution becomes progressively lighter with time. In the absence of any evidence for secondary mineral formation the most likely explanation for these light Mg isotope compositions is that there has been preferential loss of light Mg during primary phase dissolution.For the experiments undertaken at close to equilibrium conditions the results of saturation state modelling and changes in solution chemistry suggest that secondary mineral formation has occurred. X-ray diffraction (XRD) measurements of the reacted mineral products from these experiments confirm that the principal secondary phase that has formed is chrysotile. Lithium isotope ratios of the experimental fluid become increasingly heavy with time, consistent with previous experimental work and natural data indicating that ⁶Li is preferentially incorporated into secondary minerals, leaving the solution enriched in ⁷Li. The behaviour of Mg isotopes is different from that anticipated or observed in natural systems. Similar to the far from equilibrium experiments initially light Mg is lost during olivine dissolution, but with time the δ²⁶Mg value of the solution becomes increasingly heavy. This suggests either preferential loss of light, and then heavy Mg from olivine, or that the secondary phase preferentially incorporates light Mg from solution. Assuming that the secondary phase is chrysotile, a Mg-silicate, the sense of Mg fractionation is opposite to that previously associated with silicate soils and implies that the fractionation of Mg isotopes during silicate precipitation may be mineral specific. If secondary silicates do preferentially remove light Mg from solution then this could be a possible mechanism for the relatively heavy δ²⁶Mg value of seawater. This study highlights the utility of experimental studies to quantify the effects of natural weathering reactions on the Li and Mg geochemical cycles.     

The effect of prolonged X-ray irradiation on lithium tetraborate glass discs as used in X.R.F. analyses

Prolonged irradiation by X-rays of lithium tetraborate glass discs causes significant changes in countrates for certain elements e.g. Na and Mg decrease while Al, Si and P increase. This effect is probably due to surface diffusion in the glass as grinding away about 10 μm of the surface of the disc restores the countrates to their original levels. Although no change in countrates will ever be noticed on individual glass discs undergoing routine analyses, where irradiation time is only a minute or so, a close watch must be kept on any specimens that have been irradiated for more than a few tens of hours.     

新生碳酸钙沉积矿物形态的影响因素分析

石笋是古气候重建的重要地质载体,文石与方解石是石笋碳酸钙晶体的常见矿物形态。根据现代洞穴监测数据分析洞穴新生碳酸钙沉积物 (Active Speleothem: AS)的矿物形态的研究较少。本文在重庆武隆芙蓉洞三个滴水点 (MP2、MP5、MP9)下放置玻璃片,收集新生碳酸钙沉积物和滴水样品,监测新生碳酸钙沉积物矿物形态、滴水的Mg/Ca比值、pH、滴率和洞穴环境等指标,分析玻璃片正面和反面新生碳酸钙沉积物的δ18O、δ13C和Mg/Ca比值。研究发现:(1) MP2滴水点下的玻璃片正反面新生碳酸钙沉积物的矿物形态均为方解石;MP5和MP9滴水点的正面沉积方解石和文石-方解石混合两种情况,反面沉积文石-方解石,且反面文石多于正面。 (2) MP2滴水Mg/Ca比值小于MP5和MP9,说明滴水Mg/Ca比值是影响新生碳酸钙沉积物矿物形态的重要因素;而滴水pH值对AS矿物形态的影响在不同滴水点有差异。(3) 不论是玻璃片正面还是反面,文石-方解石混合的新生碳酸钙沉积物δ18O和δ13C比以方解石为主的沉积物偏正,说明AS矿物形态的变化会导致δ18O和δ13C发生变化。通过在芙蓉洞的系统监测和分析,发现新生碳酸钙沉积物的矿物形态与地表环境、洞穴上部岩溶水文地质条件密切相关,并验证了洞穴新生碳酸钙沉积物的矿物形态对石笋δ18O和δ13C具有重要影响。      

Suspended basaltic glass–seawater interactions

The objective of this study was to quantify by experiments the initial seawater–suspended basaltic glass interactions following the 1996 outburst flood from the Vatnajökull glacier, Iceland. The altered basaltic glass dissolved in seawater as recorded by the Si release from the glass. The dissolved concentrations of Na, Ca, Si, Ba, Cd, Co, Cu, Hg, Mn, Ni and total dissolved inorganic N increased with time but the concentrations of Mg, K, S, Sr, Fe, Pb and Zn decreased. Calculated 1 to 10 day fluxes for Si range from 38,000 tons/day to 70,000 tons/10 days. The fluxes for other major elements are more uncertain, but the positive flux (release from suspended matter to seawater) of Ca and Na, and negative flux of Mg, K and S are greater than the Si flux.     

Na, Mg, Ni and Cs distribution and speciation after long-term alteration of a simulated nuclear waste glass: A micro-XAS/XRF/XRD and wet chemical study

Microscopic distribution and speciation of Na, Mg, Ni and Cs in a simulated (inactive) nuclear waste glass were studied using micro X-ray fluorescence (μ-XRF) and micro X-ray absorption spectroscopy (μ-XAS), after aqueous leaching during 12 years at 90 °C. Na and Mg are major constituents of the glass that can be used to determine the progress of the glass corrosion process and the nature of secondary alteration phases. Ni and Cs represent dose determining long-lived radionuclides (⁵⁹Ni, ¹³⁵Cs) in vitrified nuclear waste.The Na-Mg μ-XRF maps revealed that the core regions of the glass fragments are apparently unaltered and compositionally homogeneous, whereas rims and interstitial spaces are enriched with Mg-rich smectite formed during the leaching process. The micro X-ray absorption near edge structure (μ-XANES) spectra collected at the Mg K-edge in the altered zones show three sharp resonances typical for crystalline Mg-silicates. These resonances are distinctive of Mg occupying undistorted octahedral positions. In contrast, the μ-XANES spectra collected in the core zones of the glass fragments lack this resonance pattern and are identical to the spectra measured on the pristine (unleached) MW glass.Micro extended X-ray absorption fine structure (μ-EXAFS) and μ-XANES analyses at the Ni K-edge revealed three distinct Ni(II) species: (a) Ni uniformly distributed in the glass matrix, (b) micro-inclusions with high Ni concentrations and (c) Ni associated to the Mg-clay. The comparison with reference spectra of unleached MW and other Ni-bearing silicate glasses indicated that species (a) represents the original coordinative environment of Ni in the glass. The μ-EXAFS analyses revealed that species (b) is structural Ni in trevorite (NiFe₂O₄), which probably formed through unmixing processes during the cooling of the glass melt. The μ-EXAFS of species (c) could be successfully modeled assuming specific adsorption or incorporation of Ni into the lattice of trioctahedral Mg-clay minerals. Alternative models assuming other elements (Ni, Al, Fe) in addition to Mg in the second shell could not be fitted successfully.Aqueous concentration data were used to calculate the speciation of the leaching solutions. Saturation index (SI) calculations indicate undersaturation with respect to NiCO₃ and NiSO₄·7H₂O, but oversaturation with respect to β-Ni(OH)₂. The latter result is probably due to the omission of Ni borate and Ni silicate complexes in the speciation calculations, for which formation constants are not available. With the help of estimation techniques, we could infer that such complexes would dominate the Ni speciation and consequently reduce the SI below the saturation of β-Ni(OH)₂.The μ-XRF maps show that Cs is uniformly distributed in the MW glass, since no region with high Cs concentration could be detected. The Cs L_III-edge μ-XAS spectra were all very similar independently of the degree of alteration, indicating similar coordination environments of Cs in the core regions of the glass as well as in the secondary clays. These spectra largely differ from that measured for pollucite (a potential secondary Cs-phase in altered glasses) implying that the coordination environments of Cs in the MW glass and in pollucite are fundamentally different.The present study shows that μ-XRF and μ-XAS are essential tools in determining the fate and the retention mechanisms of radionuclides released from nuclear waste during aqueous alteration. Our spectroscopic analyses allowed us to exclude formation of specific Ni and Cs secondary solids (e.g. nepouite, β-Ni(OH)₂, pollucite) during the aqueous alteration. Ni and Cs are instead distributed as trace elements in the alteration phases formed by major elements during the leaching process. Our results imply that solid solution and/or adsorption equilibria, rather than pure phase solubility equilibria, are the adequate chemical models to determine Ni and Cs aqueous concentrations in performance assessments for radioactive waste repositories.