Electron Probe Studies Research Articles

Jewelry and ornamental concretions with fossils of the Republic of Kabardino-Balkaria. Mineral composition, gemological characteristics

Background. Along with ammonites and septaries, concretions with fossils are increasingly being used as jewelry and ornamental materials in Russia. Such concretions are characterized by a wide range of sizes, as well as high decorative and technological properties, making them attractive materials for manufacturing diverse interior and jewelry products. The collection and processing of concretions with fossils was previously carried out in the Ulyanovsk region. In this paper, similar concretions found in the Republic of Kabardino-Balkaria are studied for the first time.Aim. Tо establish the stratigraphic position, mineral composition, and decorative and technological characteristics of concretions with fossils of jewelry and ornamental quality found in the Republic of Kabardino-Balkaria.Materials and methods. The collection sites of concretions with fossils and their stratigraphic position were studied. In total, 15 samples characterizing the main decorative and technological types were selected. Interior and jewelry items were manufactured from the concretions; typical samples were studied. A set of studies included the determination of luminescence (8 samples), microhardness (8 cycles), density (6 cycles), optical-petrographic analysis (3 sections), quantitative determination of mineral and chemical composition (2 samples), electron probe studies (2 samples).Results. Concretions with fossils of commercial quality are associated with lower Aptian deposits, representing marlstone with a large number of shells, mainly ammonites, and, to a lesser extent, bivalves. These comprise (wt %): calcite — 64.0, quartz — 18.7, microcline — 7.4, illite — 5.6, smectite — 2.7, kaolinite — 1.0, strontianite — 0.5, as well as traces of pyrite, apatite, albite, ilmenite, and goethite. Among the impurity elements, Sr in the amount of 0.0402 wt % is recorded.Conclusions. For the first time, the mineral and chemical (including micro-inclusions and impurity elements) composition of concretions with fossils of jewelry and ornamental quality are established. Factors determining their decorative and technological characteristics are identified. The possibility of using concretions with fossils for manufacturing a wide range of products, including jewelry, is shown. Concretions can be collected simultaneously with ammonites and septaries in river valleys without mining, thereby involving minimal costs and having no negative effect on the environment.

Mending cracks atom-by-atom in rutile TiO2 with electron beam radiolysis

Rich electron-matter interactions fundamentally enable electron probe studies of materials such as scanning transmission electron microscopy (STEM). Inelastic interactions often result in structural modifications of the material, ultimately limiting the quality of electron probe measurements. However, atomistic mechanisms of inelastic-scattering-driven transformations are difficult to characterize. Here, we report direct visualization of radiolysis-driven restructuring of rutile TiO2 under electron beam irradiation. Using annular dark field imaging and electron energy-loss spectroscopy signals, STEM probes revealed the progressive filling of atomically sharp nanometer-wide cracks with striking atomic resolution detail. STEM probes of varying beam energy and precisely controlled electron dose were found to constructively restructure rutile TiO2 according to a quantified radiolytic mechanism. Based on direct experimental observation, a “two-step rolling” model of mobile octahedral building blocks enabling radiolysis-driven atomic migration is introduced. Such controlled electron beam-induced radiolytic restructuring can be used to engineer novel nanostructures atom-by-atom.

Jewelry Morocco septaria. Gemological characteristics and mineral composition

Background. Septaria, comprising calcareous-clay nodules with calcite veins, are widely used as jewelry and ornamental materials. Septaria from Morocco represented on the world and Russian markets of jewelry and ornamental stones remain gemologically and mineralogically underexplored. In this article, the gemological characteristics and mineral composition of Morocco septaria, as well as the conditions of their formation, are described for the first time.Aim. To determine the gemological characteristics and mineral composition of Morocco septaria, as well as their formation conditions. To conduct their comparison with septaria from other regions of the world.Materials and methods. The author studied the assortment of Morocco septaria presented at international and Russian exhibitions. A collection (15 samples) representing the main decorative septarium varieties was compiled. The materials underwent determination of microhardness, density, luminescence (10 samples), optical-petrographic analysis (4 sections), quantitative determination of mineral and chemical composition (2 samples), electron probe studies (2 samples).Results. The septaria were found to consist of (wt %): quartz — 38, goethite — 16, chlorite (shamosite) — 28, kaolinite — 6, siderite — 5, dolomite — 4, calcite — 1, pyrite, zeolite, apatite, hydrosludes less than 1. Dispersed inclusions of leucoxene, barite, and microcline were discovered. The septarium veins consisted mainly of dolomite, quartz, chlorite with inclusions of siderite, calcite and pyrite. The Zn, Sr, and Ba impurities ranged within 0.01—0.05 wt %, while Cr, V, Ni, Cu, Rb, Zr, Y, and Pb ranged within 0.001—0.01 wt %. The mineral composition of the studied Morocco septaria was found to differ significantly from that of septaria in other regions of the world, where calcite plays a decisive role.Conclusion. Morocco septaria of small size (from 2 to 6 cm) are used as interior decorations and jewelry cabochons. The mineral and chemical (including micro-inclusions and impurities) composition of Morocco septaria was established for the first time, which allows their identification. The mineral composition of the septaria under study is associated with the regional low-temperature metamorphism, which altered the original, predominantly calcite composition.

Mineralogy of interior jewellery ammonites of the Samara region

Background. Ammonite products are increasingly gaining in popularity. Ammonites are characterised by a variety of colour shades, shapes and sizes, making them suitable for manufacturing a wide range of souvenir and jewellery products. Russia enjoys significant resources of ammonites of interior and jewellery-ornamental quality; however, these materials remain insufficiently studied from the mineralogical point of view. This article presents the mineral composition and gemological characteristics of the Upper Jurassic interior jewellery ammonites of the Samara region for the first time.Aim. To describe the stratigraphic position and mineral composition of interior jewellery ammonites of the Samara region.Materials and methods. Late Jurassic ammonites (45 samples) were collected from a number of their main locations. The characteristic types of ammonites of interior-jewellery quality were distinguished and studied. Experiments included the determination of microhardness (25 determinations), density (12 determinations), luminescence features (10 samples), optical and petrographic analysis (5 thin sections), as well as the quantitative determination of mineral and chemical composition (3 samples), and electron probe studies (2 samples).Results. Ammonites are characterized by the presence of a mother-of-pearl layer with multi-coloured iridescence. The ammonites under study consist mainly of apatite (21—70 wt. %) and calcite (21—87 wt. %) along with quartz, aluminosilicates, gypsum, pyrite, zeolites, goethite, ilmenite and organic matter. The chambers of ammonite shells are made of phosphorite and calcite. The walls and partitions of shells have completely lost their original aragonite composition and consist of apatite and calcite with pyrite inclusions. The increased content of Sr (up to 0.17 wt. %) and Ba (up to 0.01 wt. %) are recorded as trace elements in ammonites. Calcite contains the following trace elements (wt. %): Mg — 0.17, Mn — 0.17, Fe — 1.14, Sr — 0.11, and Y — 0.17.Conclusion. The mineral and chemical (including microinclusions and trace elements) composition of interior-jewellery ammonites was established for the first time. The ammonites of the Samara region are of commercial interest as interior samples. Their shell fragments can be used in jewellery production. The ammonites under study can be collected along the coastal cliffs and beach area of the Volga river, thereby requiring no capital investments and producing no environmental pollution.

Formation mechanism and antisite defects of scalable room-temperature aqueous synthesis of SnSe: Effects of the pH value on the reaction yield, mean crystallite size, chemical composition, and carrier concentration

A simple and scalable wet chemical method was adopted to synthesize a series of single-phase nanosized SnSe at room temperature with the solution controlled at various pH values. The lattice constants, chemical compositions, carrier concentration, bond length of bonded atoms, reaction yield, and antisite defects of resulting materials exhibit significant dependence on the pH values of the aqueous solution in the synthesis. Detailed studies on the formation mechanism of SnSe indicate that our approach involves the reaction between elemental Sn and Se, instead of the competitive precipitating reaction between Sn2+ and Se2−. The energetic elemental Se might be provided by polyselenide ions Sex2−. The reaction yield increases after treating SnSe with hydrochloric acid. According to both elemental analyses using electron probe microanalyzer and studies of extended x-ray absorption fine structure spectra, the Se vacancy is generated and is accompanied by formation of antisite defects by treating SnSe with hydrochloric acid.

ЗАКОНОМЕРНОСТИ ПРОТЕКАНИЯ ПРОЦЕССОВ ФОРМИРОВАНИЯ СТРУКТУРЫ И ПРОЧНОСТИ БЕСКЛИНКЕРНОГО ВЯЖУЩЕГО ЩЕЛОЧНОЙ АКТИВАЦИИ

resource- and energy-consuming Portland cement is currently considered the most popular material in the construction industry, but its production can be attributed to the category of harmful industries in terms of the amount of emissions into the environment. Therefore, the development of a clinker-free technology for the production of binders based on mineral fine powders of aluminosilicate nature activated by an alkaline coater is a relevant and promising direction.
 In the work, the laws of the processes occurring during the structure formation of clinker-free binder systems of alkaline activation on alkaline cements using blast furnace granulated slags in a finely dispersed state are studied. Formulations are given and the properties of clinker-free binders of alkaline activation on mineral fine powders from rocks of sedimentary and magmatic origin are investigated. Electron probe studies and X-ray phase analysis revealed the presence of hydrated amorphous compounds close in composition to zeolites in cement stone. An analysis of the results allowed us to determine the optimal composition of clinker-free binder alkaline activation “silicified marl + volcanic tuff (70: 30%) + Na2Si03 + Na0H” with activity ranging from 42.0 - 54.5 MPa, depending on the conditions of hardening of the samples.

THEORETICAL BASIS OF COMPATIBILITY OF COMPLETELY-FILLED MULTICOMPONENT BINDING SYSTEMS

Abstract. Aim. An important direction in contemporary concrete science is aimed at the development of multicomponent systems using mineral powder fillers in a finely dispersed state to create strong and durable building composites. One of the most significant factors affecting the properties of multicomponent systems is the compatibility of its components. Efforts on the part of leading scientific institutes are aimed at replacing expensive and energy-intensive Portland cement with composite concrete products produced using mixed binders. In this context, the development of modern effective composites based on clinkerless alkaline binders becomes an urgent problem. Methods. Studies into the compatibility of multicomponent cementing systems are based on a contemporary technological approach that contributes to the production of strong and durable cement stone, without the use of traditional Portland cement. Results. Electron probe studies and X-ray phase analysis of concrete produced using a clinker-free alkaline activation binder showed that the studied multicomponent system contains a hydro-aluminosilicate zeolite phase of variable composition, as well as indicating the presence of calcite, quartz, albite feldspar, mica, zeolites and potassium feldspar. Conclusion. The results of the studies confirm the compatibility of all components of the multicomponent system comprised of mineral powder, alkaline coater and surfactant. The proposed technological method can be used to produce strong and durable building composites with clinker-free technology avoiding the use of expensive and energy-intensive Portland cement. Acknowledgments. The work was performed as part of research on the implementation of scientific project No. 05.607.21.0320. “Development of technology for new building composites on clinker-free alkaline binders using substandard natural and secondary raw materials” which received support from the federal target program “Research and Development in Priority Directions for the Development of the Russian Science and Technology Complex for 2014-2020.” Unique identifier for the agreement RFMTFI60719X0320.

Mineralogy of tin-sulfides in the Zijinshan porphyry–epithermal system, Fujian Province, China

The Zijinshan orefield is a Cu–Au–Mo–Ag porphyry–epithermal mineralization system of Cretaceous age in southeastern China, comprising the Zijinshan high-sulfidation (HS) Au–Cu deposit, Luoboling porphyry Cu–Mo deposits, Yueyang low-sulfidation Au–Ag–Cu deposit, and Wuziqilong and Longjiangting intermediate-sulfidation (IS) Cu deposit. A number of Sn-(W)-sulfides occur in the Zijinshan orefield, including kiddcreekite, hemusite, colusite, vinciennite, stannoidite, mawsonite and kësterite. The occurrence represents the first report of hemusite, colusite and vinciennite in China. The relative abundance and diversity of Sn-(W)-sulfide-bearing assemblages make the Zijinshan orefield possibly unique in the world, and carries implications for the evolution of the mineralizing environment. Detailed electron probe studies of the Sn-minerals reveal that kiddcreekite, hemusite, mawsonite, stannoidite and kësterite have compositions close to ideal formulae. In contrast, colusite displays grain-scale zoning expressed by W, Sn and As. Vinciennite displays compositional variation depending on mineralization style: an average composition of Cu10.74Fe3.88Sn(As0.85,Sb0.08)S15.4 in the Zijinshan HS deposit, Cu10.71Fe3.9SnAs0.85S15.34 in the Wuziqilong Cu deposit and Cu10.76Fe3.7Sn1.02 (As0.5,Sb0.45)S15.54 with higher Sb contents (3.32%) in the adjacent Longjiangting Cu deposit.In the Zijinshan HS Au–Cu deposit, the main Cu-mineral assemblage varies from bornite-rich to digenite- to covellite-rich with increasing depth. Correspondingly, tin mineralogy varies from kësterite at upper levels to stannoidite-dominant at mid-to-upper levels of the copper orebody, to vinciennite- and mawsonite-dominant at depth, implying an increase in sulfidation and oxidation state downwards. Moreover, kiddcreekite is always partially replaced by wolframite and (hypogene) covellite at depth, also indicating overprinting by high-fO2 and -fS2 fluids in the covellite stage of mineralization. Kiddcreekite, along with a primary chalcopyrite–pyrite mineral association, occurs widely in the Zijinshan orefield (Zijinshan, Yueyang, Luoboling, Wuziqilong, Longjiangting and Dayanli), and is likely indicative of the early IS stage of epithermal system. Analogous with published data, kiddcreekite most commonly occurs in porphyry-style mineralization, implying the presence of the mineral has potential as an indicator of porphyry systems. Vinciennite-bearing Cu–Sn–As mineral associations occur in a specific position in the Zijinshan HS Au–Cu, Wuziqilong and Longjiangting Cu deposits, indicative of a transitional zone between porphyry and HS epithermal-style mineralization. The occurrence of the identified Sn-(W)-sulfide-bearing assemblages has considerable potential implications for understanding the architecture of a complex porphyry–epithermal environment and for exploration for underlying porphyry copper deposits. There is potential for discovery of a subjacent porphyry Cu deposit within the Zijinshan orefield.

Complex investigation of multilayer nanostructure of a-Si/SiO1.9 by probe and spectroscopic analysis techniques. Visualization of the band structure. Studying of the band structure of the suboxide border layers

This article describes an integrated approach to the study of multilayer nanostructures of a-Si/SiO1.9 as a potential model to study the influence of the effects arising at the interface of Si/SiO2 under the influence of ionizing radiation. The results of the functional layers of amorphous silicon and silicon dioxide surface topology investigation have been disclosed. The possibility of application of a band gap contrast in electron probe studies by means of electron energy filtering during the detection process has been demonstrated. Changes in valence band and band gap through depth of the a-Si/SiO1.9 nanostructure have been registered. As part of the study, density of states of the a-Si/SiO1.9 multilayer nanostructures and depth distribution of surface suboxide layers of native oxide of amorphous silicon have been reconstructed using the determination of an effective mean free path of the electrons by the TPP2M algorithm in conjunction with PARXPS and REELS measurements. Copyright © 2015 John Wiley & Sons, Ltd.

Spinels, Fe–Ti oxide minerals, apatites, and carbonates hosted in the ophiolites of Eastern Desert of Egypt: mineralogy and chemical aspects

Spinels, Fe–Ti oxide minerals, apatites, and carbonates hosted in ophiolitic serpentinites and metagabbros of Gabal Garf (southern ED) and Wadi Hammariya (central ED) of Egypt are discussed. Microscopic and electron probe studies on these minerals are made to evaluate their textural and compositional variations. Alteration of chromites led to form ferritchromite and magnetite; rutile–magnetite intergrowths and martite are common in serpentinites. Fine trillis exsolution of ilmenite–magnetite and ilmenite–hematite and intergrowth of rutile–magnetite and ilmenite–sphene are recorded. Composite intergrowth grains of titanomagnetite–ilmenite trellis lamellae are common in metagabbros. The formation of ilmenite trellis and lamellae in magnetite and titanomagnetite indicate an oxidation process due to excess of oxygen contained in titanomagnetite; trapped and external oxidizing agents. This indicates the high PH2O and oxygen fugacity of the parental magma. The sulfides minerals include pyrrhotite, pyrite and chalcopyrite. Based on the chemical characteristics, the Fe–Ti oxide from the ophiolitic metagabbros in both areas corresponds to ilmenite. The patites from the metagabbros are identified as fluor-apatite. Carbonates are represented by dolomites in serpentinites and calcite in metagabbros. Spinel crystals in serpentinites are homogenous or zoned with unaltered cores of Al-spinel to ferritchromit and Cr-magnetite toward the altered rims. Compared to cores, the metamorphic rims are enriched in Cr# (0.87–1.00 vs. 0.83–0.86 for rims and cores, respectively) and impoverished in Mg# (0.26–0.48 vs. 0.56–0.67) due to Mg–Fe and Al (Cr)–Fe3+ exchange with the surrounding silicates during regional metamorphism rather than serpentinization process. The Fe–Ti oxides have been formed under temperature of ~800 °C for ilmenite. Al-spinels equilibrated below 500–550 °C, while the altered spinel rims correspond to metamorphism around 500–600 °C. Geochemical evidence of the podiform Al-spinels suggest a greenschist up to lower amphibolite facies metamorphism (at 500–600 °C), which is isofacial with the host rocks. Al-spinel cores do not appear to have re-equilibrated completely with the metamorphic spinel rims and surrounding silicates, suggesting relic magmatic composition unaffected by metamorphism. The composition of Al-spinel grains suggest an ophiolitic origin and derivation by crystallization of boninitic magma that belonging to a supra-subduction setting could form either in forearcs during an incipient stage of subduction initiation or in back-arc basins.

Aluminium and Alzheimer's disease.

The hypothesis that aluminium (Al) is a cause of (or a risk factor in) the development of beta-amyloid plaques and neurofibrillary tangles (NFT) and dementia in Alzheimer's disease (AD) is based on studies by Wisniewski et al, Klatzo et al and Terry & Peña in 1965 that showed that injection of experimental animals with Al compounds induces the formation of NFT. Other publications revealed that Al affects cognitive functions in experimental animals and humans undergoing dialysis for renal failure. Electron probe and laser microprobe mass analysis (LAMMA) studies have demonstrated the presence of Al in NFT and cores of amyloid stars and nuclei of neurons in AD patients. Other studies have indicated the association between amyotrophic lateral sclerosis/Guam parkinsonism-dementia complex and Al in the environment. A recent report suggests that the chelating agent desferrioxamine slows the rate of cognitive decline in AD patients. Extensive studies of the pathology of AD and Al-induced encephalopathy by our group and others indicate that Al does not cause Alzheimer's disease neuropathology. However, under certain conditions, cognition can be affected when Al enters the brain. Therefore, for individuals with renal failure or undergoing dialysis or individuals with a damaged blood-brain barrier, the intake of Al should be controlled.

Inferred phase relations in part of the system Au?Ag?Te: an integrated analytical study of gold ore from the Golden Mile, Kalgoorlie, Australia

Integrated X-ray powder diffraction, scanning electron microscopy, electron probe, and transmission electron microscopy studies have identified the rare contact assemblage calaverite–sylvanite–hessite in a sample of gold ore from the Golden Mile deposit, Kalgoorlie, Australia. The presence of coexisting calaverite–hessite at Kalgoorlie is a non-equilibrium assemblage whereby the stable hessite-bearing assemblage is hessite–sylvanite, which formed from the breakdown of the γ-phase or χ-phase below 120 °C, stutzite+γ-phase, or sylvanite+stutzite+γ-phase, as predicted by Cabri (1965).

Evidence of Sr mobility in and around the albite?lepidolite?topaz granite of Beauvoir (France): an in-situ ion and electron probe study of secondary Sr-rich phosphates

The Beauvoir albite–lepidolite–topaz granite is a small, highly evolved intrusion, rich in Li, Rb, F, but also paradoxically rich (or enriched) in Sr (up to 755 ppm) and Ca, a provocative chemical contradiction. Goyazite, an Sr-rich phosphate, is ubiquitous as small secondary grains growing exclusively in albite. Ion microprobe spot analyses reveal variable, higher than whole-rock 87Sr/86Sr ratios at the crystal scale. These data suggest exchanges between the granite and the surrounding micaschists. A two-stage scenario is proposed: (1) Sr, mainly common, was introduced from the micaschists into the Sr-poor granite at the vanishing time of crystallization, redistributed into zones of preferential permeability and stored in recrystallized P-rich albite, (2) the low-temperature destabilization of albite and lepidolite (host for radiogenic Sr produced by in-situ radioactive 87Rb decay), during the Oligocene extensive period, provoked the consequent mixture of both Sr in variable proportions, resulting in the precipitation of goyazite. These results highlight the strong disturbance affecting the Rb–Sr granite system which can be visualized in secondary minerals, such as these low-temperature, micron-size Sr-rich phosphates.

Germanium phosphide coatings from the atmospheric pressure chemical vapour deposition of GeX 4 (X=Cl or Br) and PCyc hexH 2

Atmospheric pressure chemical vapour deposition of germanium phosphide thin films was achieved on glass substrates from the reaction of GeCl 4 or GeBr 4 with PCyc hexH 2 at 600 °C. These coatings show good uniformity and surface coverage. They are reasonably adherent, passing the Scotch tape test. The films were translucent in appearance with regions of birefringence. The films were X-ray amorphous. Scanning electron microscopy showed surface morphologies consistent with an island growth mechanism. X-ray photoelectron spectroscopy binding energy shifts for GeP 1.00 were 1218.2 eV for Ge 2P 3 and 131.5 eV for P 2p 3/2. Energy dispersive X-ray analysis and electron probe studies gave elemental ratios that were in agreement indicating films which varied from being germanium rich (Ge 3P) to phosphorus rich (GeP 2), with negligible chlorine or bromine incorporation dependent on deposition conditions. No Raman scattering was observed. Sheet resistance measurements indicated the films were poor conductors. Optically the films showed poor reflectance (5–10%) and 60–80% total transmission from 400 to 1000 nm. UV–Vis spectroscopy indicated an indirect band gap of 1.1 eV. Contact angle measurements were in the range 60°–80° and showed no significant change after 60 min irradiation with 254 nm UV light.

Tin phosphide coatings from the atmospheric pressure chemical vapour deposition of SnX 4 (X=Cl or Br) and PR xH 3− x (R=Cyc hex or phenyl)

Atmospheric pressure chemical vapour deposition (APCVD) of tin phosphide thin films was achieved on glass substrates from the reaction of SnCl 4 or SnBr 4 with R x PH 3− x (R=Cyc hex or phenyl) at 500–600 °C. These coatings show good uniformity and surface coverage. They are reasonably adherent, passing the Scotch tape test. The films were largely opaque in appearance with regions of birefringence. The films were X-ray amorphous. Scanning electron microscopy (SEM) showed surface morphologies consistent with an island growth mechanism. X-ray photoelectron spectroscopy (XPS) binding energy shifts for SnP 1.00 were 487.2 eV for Sn 3d 5/2 and 133.6 eV for P 2p 3/2. Energy dispersive X-ray analysis (EDXA) and electron probe studies gave elemental ratios that were in agreement indicating slightly tin rich and stoichiometric films, with negligible chlorine or bromine incorporation (SnP 1.33–SnP 0.40). No Raman scattering was observed. Sheet resistance measurements indicated the films were insulating. Optically the films showed very poor reflectance (approximately 2%) and 5–20% total transmissions from 300 to 800 nm. Contact angle measurements were in the range 70–80°, and showed little change after 60-min irradiation at 254 nm.

Titanium Phosphide Coatings from the Atmospheric Pressure Chemical Vapor Deposition of TiCl4 and RPH2 (R = t-Bu, Ph, CyHex)

Atmospheric pressure chemical vapor deposition of titanium phosphide coatings was achieved on glass substrates from the reaction of TiCl4 and RPH2 (R = t-Bu, Ph, Cy-hex) at 450-550 degreesC. The coatings show good uniformity, surface coverage, and adherence; they passed the Scotch brand tape test and could not be scratched with a brass scalpel. The leading edge of the titanium phosphide films was a deep blue while the bulk of the film was reflective and silver. Growth rates were on the order of 1 mum min(-1) at 550 degreesC. The films were crystalline, single phase with a hexagonal cell of a = 3.49(1) Angstrom and c = 11.70(1) Angstrom. Scanning electron microscopy (SEM) revealed surface morphologies consistent with an island growth mechanism. X-ray photoelectron spectroscopy (XPS) binding energy shifts were at 454.6 eV for Ti-2p and at 128.6 eV for P-2p. Energy-dispersive X-ray analysis (EDXA) and electron probe studies gave elemental ratios that were in agreement indicating in most cases slightly P-rich films, TiP1.2, with negligible chlorine incorporation. Raman spectra exhibited bands at 245, 320, and 410 cm(-1). Sheet resistance measurements showed typically 10-120 mOmega cm, indicating good conductivity. Rutherford backscattering showed a bulk composition of TiP1.2. Optically, the films showed high reflectivity at 1000 nm and showed 5-25% total transmission from 300 to 800 nm. Contact angle measurements were in the range 40-50degrees for the as made films these showed little change after 30 min of irradiation at 254 nm. All of the films showed negligible photocatalytic activity in the destruction of an overlayer of stearic acid.

The dual source APCVD of titanium nitride thin films from reaction of hexamethyldisilazane and titanium tetrachloride

Atmospheric pressure chemical vapour deposition reaction of TiCl4 and NH(SiMe3)2 at 300–550 °C produced films of titanium nitride on glass substrates. The films were gold or purple/gold in colour, highly reflective in the infrared but with significant transmittance in the visible. Growth rates were typically 300 nm min−1 at 550 °C. The films were uniform, adhesive, abrasive resistant, conformal and hard, being resistant to scratching with a steel scalpel. They also showed no change in optical properties on immersion in common solvents or dilute acids or alkalis (2 M). X-Ray diffraction showed preferred growth in the (2 0 0) direction, typical cell constants of 4.23(1) A and a crystallite size of ca. 200 A. Raman spectra matched powder samples. SEM indicated the films were composed of ca. 200 nm particles. EDAX and electron probe studies showed no carbon or silicon impurities and a titanium to nitrogen ratio corresponding to TiN0.95. X-Ray photoelectron spectroscopy gave binding energy shifts for Ti2p3/2 and N1s at 455.8 and 396.9 eV respectively. The sheet resistance of the films showed increase conductivity with deposition temperature. The titanium nitride films showed potential for heat mirror applications.

Chemical Composition and Crystalline Structure of Hypoplastic Primary Dental Enamel

The present study, reports the chemical composition of hypoplastic primary teeth examined by electron probe microanalyzer comparing with the normal part in the same tooth; and reports the X-ray diffraction results of the hypoplastic dental enamel and the normal dental enamel, and comparing the crystalline structure between the two dental enamel together with that of the synthetic hydroxyapatite. The aim of this study was to find out any change of crystalline structure. Two exfoliated hypoplastic deciduous anterior teeth were used for the electron probe study. Each tooth was sliced into two parts along the defect lesion border in a labio-lingual direction. The normal part was used as control. Determinations of weight percentage (wt%) per mass volume were made in continuous scan for P, Al, Mg, Ca, Mn, Fe, Zn, Sr, Na, K and F, from the enamel edge of hypoplastic bottom to dentin-enamel junction. Four exfoliated hypoplastic deciduous anterior teeth and eight exfoliated normal deciduous anterior teeth were used for the X-ray diffraction study. We found by X-ray diffraction that the length of the a-axis of enamel crystallite and the d-spacing (corresponding 300) were increased in the defective enamel. These could be associated with the increased content of magnesium detected by electron probe. The present study demonstrated that there were both quantity and quality changes in the enamel hypoplasia lesion, which may increase the susceptibility of the defective teeth to caries.

Geochemical study of gold and arsenic mineralization of the carlin-type gold deposits, Qinling Region, China

Element geochemistry of gold and arsenic and mineralogical features of their sulfides in the Carlin-type gold deposits of the Qinling region are discussed in this paper. The initial contents of ore-forming elements such as gold and arsenic are high in the ore-bearing rock series in the Qinling region. Furthermore, both the metals are concentrated mainly in the diagenetic pyrite. Study on the mineralogy of arsenic-bearing sulfide minerals in the ores demonstrated that there is a positive correlation between gold and arsenic in the sulfide minerals. Available evidence suggests that gold in the As-bearing sulfide minerals is likely to be presented as a charge species (Au+), and it is most possible for it to replace the excess arsenic at the site of iron and was probably deposited together with arsenic as solid solution in the sulfide minerals. Pyrite is composed of (Aux3+, Fe1−x2+) ([AsS]x3− [S2]1−x2−, and arsenopyrite of (Aux3+, Fe1−x3+) ([AsS]x3− [AsS2]1−x3−). The occurrence of gold in the As-sulfide minerals from the Carlin-type gold deposits in the Qinling region has been confirmed by electron probe and transmission electron microscopic studies. The results show that gold was probably deposited together with arsenic as coupled solid solutions in sulfide minerals in the early stage of mineralization. Metallogenic chemical reactions concerning gold deposition in the Carlin-type As-rich gold deposits would involve oxidation of gold and concurrent reduction of arsenic. Later, the deposited gold as solid solution was remobilized and redistributed as exsolutions, as a result of increasing hydrothermal alteration and crystallization, and decreasing resistance to refractoriness of the host minerals. Gold occurs as sub-microscopic grains (ranging from 0.04 to 0.16 μm in diameter) of native gold along micro factures in and crystalline grains of the sulfides.

Atmospheric pressure chemical vapour deposition of vanadium nitride and oxynitride films on glass from reaction of VCl4 with NH3

Atmospheric pressure chemical vapour deposition of vanadium nitride and oxynitride coatings was achieved on glass substrates from the reaction of VCl4 and NH3 at 350–650°C. The coatings show excellent uniformity, surface coverage, adherence and a range of colours (yellow, blue–silver) dependent on deposition temperature and film thickness. Growth rates were of the order of 1 µm min−1. All films deposited at greater than 450°C were crystalline, single phase with an fcc NaCl diffraction pattern, a = 4.065–4.116(2) A. Scanning electron microscopy (SEM) revealed different film thicknesses and surface morphologies consistent with an island growth mechanism. X-Ray photoelectron spectroscopy (XPS) revealed that individual samples were homogeneous. Compositional variations between films were related to reaction conditions; VN0.8O0.18–VN0.56O0.8. XPS binding energy shifts were seen for V 2p at 513.3 eV for O 1s at 530.8 eV and for N 1s at 397.1 eV and were largely invariant between samples. Energy dispersive X-ray analysis (EDXA) and electron probe studies gave elemental ratios that were in agreement with the XPS measurements, indicating no chlorine incorporation. Raman spectra showed a broad band at 600 cm−1. Sheet resistance measurements indicated that all films were metallic. Optically, the films were reflective in the range 800–2600 nm and showed reasonable transmission in the range 300–800 nm. The films show promise as solar-control coatings.