EDS Data Research Articles

Synthesis and characterization of zinc oxide fine particles coated with titania/PDMS hybrid

Zinc oxide nanoparticles were coated with titania/polydimethylsiloxane hybrid by co-hydrolysis and co-condensation of the sols prepared from titanium tetraisopropoxide and methoxy-functionalized polydimethylsiloxane to synthesize a new class of hierarchically designed composite materials. The successful formation of the shell, which is composed of titania/polydimethylsiloxane hybrid, was evidenced by SEM, TEM, IR, EDS and zeta potential data. The hydrophobicity and the dispersibility in decamethylcyclopentasiloxane changed dramatically by the shell formation.

Alteration behaviour of glass panes from the medieval Pavia Charterhouse (Italy)

The stained glass windows of the Pavia Carthusian Monastery are an important testimony of medieval glass making in which a wood-ash flushing component was used. Glass surfaces reveal alteration processes extending to depth, with evidence of microbial corrosion. Electron microprobe analyses coupled with EDS data allow the identification of different steps in the alteration process. Microbial attack occurs in an early stage and determines component leaching of the glass, with the development of reactions in which the crystallisation of gypsum is favoured.

Poly(amino acid)-Facilitated Electrochemical Growth of Metal Nanoparticles

Poly(amino acids) are natural chelating agents for various metal ions. Zinc ions were encapsulated in situ in a conductive polypyrrole film using polyglutamic acid as a localized complexing agent within the film. The subsequent electrochemical reduction of the metal ions to zero-valent metal leads to the formation of the nanoparticles. The electrochemical approach demonstrated in this report provides facile regeneration of the particles and also prevents aggregation of nanoparticles in the conductive polymeric film. The correlation of the amount of zinc with the thickness of the film indicates that the zinc resides largely in the outer layer of the film. TEM and EDS data show that the nanoparticles formed are composed of zinc and are 18 +/- 7 nm in diameter. The nanoparticle/ polymer composite was used to reduce halogenated organics, indicating its potential usefulness in remediation applications.

Investigation of the electrical properties, charging process, and passivation of RuO2–Ta2O5 oxide films

Abstract Freshly prepared RuO2–Ta2O5 thin films containing between 10 and 80 atom% Ru have been examined and characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and morphological analysis (SEM – scanning electron microscopy/EDS – energy dispersive X-ray spectroscopy). Investigation of the electrical properties, charging process, and passivation of the electrode containing RuO2–Ta2O5 thin films was conducted as a function of electrode composition in a 0.5 mol dm−3 H2SO4 solution. For potential values in the double layer region (0.2–1.0 V vs. RHE), the impedance profile observed at low frequency domain was attributed mainly to the capacitive behavior of the oxide/solution interface. As for the high frequency domain, the impedance profile gave evidence that the kinetic process is limited by supporting electrolyte/water diffusion inside the pores of the difficult-to-access oxide regions and/or the Ti/oxide interface. The electrode passivation mechanism toward OER (oxygen evolution reaction – 1.5 V vs. RHE) was also investigated during long-term electrolysis (j = 750 mA cm−2 and T = 80 °C) by means of EIS at pre-established times. The SEM–EDS data give evidence of the increase in the TiOx interlayer. Moreover, the EIS data furnished complementary insight that helped our proposition of the deactivation mechanism.

New mineral occurrences and mineralization processes: Wuda coal-fire gas vents of Inner Mongolia

Five unique mineral assemblages that include the sulfates millosevichite, alunogen, anhydrite, tschermigite, coquimbite, voltaite, and godovikovite, as well as the halide salammoniac and an unidentified phase, according to X-ray diffraction and EDS data, were found as encrustations on quartzofeldspathic sand and sandstone adjacent to coal-fire gas vents associated with underground coal fires in the Wuda coalfield of Inner Mongolia. The mineral assemblage of alunogen, coquimbite, voltaite, and the unidentified phase collected from the same gas vent, is documented for the first time. Coquimbite also occurs as rosettes secondarily nucleated on a cryptocrystalline mass of alunogen, coquimbite, voltaite, and the unidentified phase during storage in a sealed container at room temperature. Field observations, analyses of vent gases, SEM images, and mineral compositions suggest that the sulfates millosevichite, alunogen, coquimbite, voltaite, godovikovite, and the unidentified phase, crystallized in response to a complex sequence of processes that include condensation, hydrothermal alteration, crystallization from solution, fluctuating vent temperatures, boiling, and dehydration reactions, whereas the halide salammoniac crystallized during the sublimation of coal-fire gas. Tschermigite and anhydrite formed by the reaction of coal-fire gas with quartzofeldspathic rock or by hydrothermal alteration of this rock and crystallization from an acid-rich aqueous solution. Variations in the mineral assemblages found at five gas vents are possibly due to differences in coal-bed chemistry, exchange reactions involving coal-fire gas, and the composition of sediment, rock, and aqueous solutions prior to the exhalation of gas at the surface, as well as the temperature and cooling rate at a vent. Few studies have addressed the interaction of coal-fire gas with sediment, rock, and aqueous solutions and the subsequent mineralization processes. Coal fires present opportunities for discovering rare and new mineral occurrences. These minerals have potentially important environmental significance and may be vectors for the transmission of toxins. Coal fires also provide insight for the recognition in the geologic record of preserved mineral assemblages that are diagnostic of ancient fires.

Effect of potential on bismuth telluride thin film growth by electrochemical atomic layer epitaxy

In the present study, bismuth telluride compound thin film was grown by means of electrochemical atomic layer epitaxy (ECALE) with an automated thin layer flow cell deposition system. The dependence of the Bi and Te deposition potentials on Pt electrode was studied. Because developing a contact potential between the substrate and the growing semiconductor, the deposition potential adjustment is necessary for the first 30 or more cycles of each component. The dependence of the deposit as a function of the deposition potential adjustment slope has been investigated. The results show that an excess elemental Bi existed at a slope of −2 mV/p (p indicates per cycle), indicating that this is a lack of deposition at the potential. Single-phase Bi 2Te 3 compound could be obtained between −4 and −6 mV/p. Bi 2Te 3 and Bi 4Te 3 coexistence is observed at a slope of −10 mV/p. The EDS data indicates that the stoichiometry of compound is consistent with XRD result. SEM studies show that the deposits are inhomogeneous and have an micron sized particles morphology.

Mineralogia e físico-química dos solos de mangue do rio Iriri no canal de Bertioga (Santos, SP)

A influência de condições halomórficas, hidromórficas e sulfato redutoras na mineralogia da fração argila e na geoquímica de três solos de mangue foi estudada no manguezal do rio Iriri. A partir de uma transeção, foram escolhidos três perfis representativos dos solos de mangue da área nos quais foram descritas as condições geoquímicas e sua conseqüência sobre a mineralogia de seus respectivos solos. A análise mineralógica (DRX e EDS) e as condições físico-químicas encontradas revelam a ocorrência de processos de piritização na área de estudo. A assembléia mineralógica está composta tanto por argilominerais alóctones (caulinitas, micas e esmectitas) como por argilominerais autóctones (micas, esmectitas e pirita). A partir de evidências provenientes da DRX e EDS, especula-se a formação de glauconita nestes solos. As condições de halomorfia e hidromorfia determinam valores de Eh e pH sob os quais elementos como Fe2+ e SO encontram-se livres na solução do solo com tendência à estabilidade da pirita (FeS2), favorecendo, portanto, o processo da piritização.

Aplicações de Microscopia Eletrônica de Varredura (MEV) e Sistema de Energia Dispersiva (EDS) no Estudo de Gemas: exemplos brasileiros

This paper presents results of SEM and EDS study in some Brazilian gemstones. Emerald from Campos Verdes (GO) contains several mineral inclusions as talc, dolomite, chromite, pyrite, magnetite, etc. Sylvite crystals was firstly identified by SEM/EDS. These salt inclusions suggest percolation of K-bearing fluids during emerald crystallization. Emerald from Campos Verdes present higher concentration of Cr+3 in the outer green zones than in the inner colourless zones, showing that ion is a chromophore in this gemstone. SEM and EDS results combined with optical microscopy analyses demonstrate that amethyst from Rio Grande do Sul State (RS) contain needle-like inclusions of goethite and not cacoxenite and rutile as suggest by other workers. By these techniques it was possible to identify pyrolusite and hollandite as late minerals inside agate and quartz geodes from RS. SEM and EDS data of corundum from Barra Velha (SC) show that silk effect is produced by diaspore inclusions. These techniques also reveal that the asterism in this corundum is produced by empty needle-like channels instead of the presence rutile inclusions as commonly observed in other worldwide deposits. Rounded zircon inclusions are common in corundum from Indaiá, Palmeiras, Caputira and Campo Belo (MG). Sillimanite and/or kyanite inclusions in corundum crystals of secondary deposits from Indaiá suggest a metamorphic origin to this gemstone. Corundum from Caputira also contains several rounded rutile inclusions, which are diagnostic for this occurrence.

Properties of soil kaolins from Thailand

AbstractPurified kaolins from Thai soil on diverse parent materials were characterized using analytical transmission electon microscopy, X-ray diffraction, thermogravimetric analysis and chemical analysis. The properties of Thai soil kaolins appear to be more diverse than Indonesian and Western Australian soil kaolins investigated using the same analytical procedures; this difference may reflect the greater range of parent materials for the Thai soils. The kaolins show a variety of crystal morphologies including euhedral hexagonal to subhedral platy crystals, tubes and laths and several morphologies were present in most samples. TEM-EDS enabled analysis of single crystals of each morphology present within a sample. Tubular or lath-shaped crystals usually have lower %Fe2O3 contents than hexagonal platy crystals in the same sample. The relationships between crystal size and Fe content within morphological populations were also examined by TEM-EDS. Generally, smaller kaolin crystals display a wider range of Fe concentration than the larger kaolin crystals in the same sample. Increasing Fe concentration in bulk samples is closely correlated to decreasing coherently scattering domain size (R2= 0.57), increasing cation exchange capacity (R2= 0.44) and increasing specific surface area (R2= 0.65). However the properties of the deferrated soil kaolins, including their Fe content, are not related to forms of Fe, (total Fe, amorphous or organic) in the untreated clay fraction of the soil.Inhibited vermiculite is a common minor constituent of these clay fractions and its average structural formula derived from EDS data indicates that it was formed by Al replacing K in muscovite. One Al3+ion occupies the interlayer space previously occupied by three K+ions. As the distances between these Al3+cations in the interlayer space is large it is proposed that isolated or loosely associated hydrated Al3+groups such as Al(OH2)63+exist that resist exchange by other cations due to hydrogen bonding with the adjacent tetrahedral oxygen surfaces

(Cu,Tl)Ba2Ca3Cu4Ox compositions: I. The influence of synthesis time and temperature on the phase formation and evaporation–condensation mechanism

Temperature and time dependence of the phase formation in the (Cu0.5,Tl0.5)-1234 composition have been studied. The liquid–vapour deposition mechanism for the formation of 12(n − 1)n superconducting phases is presented. XRD, SEM, EDS and weight loss data are discussed. Samples were superconducting with maximum Tc and Jc (at 60 K and 0.5 T), determined from M(H) loops of 118 K and 4 × 105 A cm−2, respectively.

Bioactivity of tape cast and sintered bioactive glass-ceramic in simulated body fluid

A common ceramic processing technique, tape casting, was used to produce thin, flexible sheets of bioactive glass (Bioglass ® 45S5) particulate in an organic matrix. Tape casting offers the possibility of producing three-dimensional shapes, as the final material is built up layer by layer. Bioactive glass tapes were sintered together to form small discs for in vitro bioactivity testing in simulated body fluid (SBF). Four different sintering schedules were investigated: 800, 900, and 1000°C for 3 h; and 1000°C for 6 h. Each schedule produced a crystalline material of major phase Na 2Ca 2Si 3O 9. Tape cast and sintered bioactive glass-ceramic processed at 1000°C formed crystalline hydroxyapatite layers after 20–24 h in SBF as indicated by Fourier transform infrared spectroscopy, Scanning electron microscopy, and EDS data. FTIR revealed that the greatest amount of hydroxyapatite formation after 2 h was observed for samples sintered at 900°C. The differences in bioactive response were likely caused by the variation in the extent of sintering and, consequently, the amount of surface area available for reaction with SBF.

Electron‐Beam‐Induced Phase Transformations from Metakaolinite to Mullite Investigated by EF‐TEM and HRTEM

Both energy‐filtered electron diffraction and EDS data clearly indicate extraction of amorphous silica from the parent metakaolinite by electron beam heating. Compared with the extracted silica through furnace heating, a larger population with inhomogeneous distribution and higher structural disorder of extracted silica by beam heating was noticed. There is a possibility that the spinel‐type phase has lower symmetry than the suggested cubic symmetry, while the 〈111〉 orientation of the spinel‐type phase is not perpendicular to the (001) plane of metakaolinite. HRTEM images of mullite crystals apparently demonstrate their random orientations with respect to the parent metakaolinite.

Development of 2201 intergrowths during melt processing Bi2212/Ag conductors

Development of 2201 intergrowths in melt-processed Bi2212/Ag tapes was studied using X-ray diffraction (XRD). The density of intergrowths evaluated from the shifts of 0 0 l peaks in the XRD patterns was found to increase with increasing maximum processing temperature T max, as well as the annealing time t max at T max varying from ∼3% ( T max=887°C, t max∼0.5 h) to ∼50% ( T max=906°C, t max∼20 h). In the tapes with high density of intergrowths, an intermediate phase of composition Bi:Sr:Ca:Cu=4:4− x:1+ x:3 ( x≈0.5) formed as evidenced from EDS data and the presence in the XRD patterns of “superstructure” (2201/2212) reflections corresponding to the lattice parameter c=2.77 nm. A rather high stability of this intermediate phase and 2201 intergrowths is related to the texture development, because, in the layered crystal structure of Bi2212, the mass transfer perpendicular to the layers is much slower than along the layers. The main implication of these findings is the understanding that achieving high grain alignment and high phase purity appear to be competitive processing goals when the microstructure develops in Bi2212/Ag tapes during melt processing.

The OH-F substitution in synthetic pargasite at 1.5 kbar, 850 °C

Amphiboles were synthesized at 1.5 kbar P H₂O and 850 °C along the join pargasite-fluoropargasite. Structural variations in the amphibole as a function of F have been characterized by a combination of SEM-EDS, X-ray powder diffraction, and infrared spectroscopy. SEM-EDS analyses show that, for increasing F in the system, there is a decrease in Altot in the amphibole and a significant decrease of F incorporation in the structure. In agreement with the EDS data, the variation in cell parameters and IR spectra show that incorporation of F in pargasite is restricted to about 1.0 atoms per formula unit (apfu). The OH-stretching spectra show fine structure caused by F replacing OH at the O3 anion site, and are consistent with two-mode behavior typical of A-site-filled amphiboles. The agreement between calculated and observed relative band intensities suggests complete short-range disorder of OH and F at the O3 anion site.

Electron Beam Induced Phase Transformations from Metakaolinite to Mullite

The kaolinite-mullite reaction series by heating has been controversial since the proposal of a new transformation mechanism. Recently energy-filtered electron diffraction data obtained from the specimen furnace-heated at 920 °C indicated that the spinel-type phase coexisted topotactically with metakaolinite. On the other hand, mullite first appeared from the specimen furnace-heated at 940 °C without showing any crystallographic relationship to the parent metakaolinite.Direct beam heating experiments of the 920 °C-heated specimens using an energy-filtering TEM supported the previous results and ideas. Fig. 1 displays topotactic coexistence of metakaolinite and the spinel-type phase (spots in hexagonal arrangement) before beam heating. Electron beam heating gave rise to a noticeable change in the diffraction pattern, that is, the formation of mullite rings and enhancement of the diffuse intensity around the direct beam shown in Fig. 2. Comparison of EDS data for the specimen before beam heating and after beam heating (Fig. 3) indicates considerable increase of Si and O peaks by beam heating.

The Au-substituted Al - Cu - Fe icosahedral phase: evidence for bond hybridization

Au-substituted Al - Cu - Fe icosahedral phases, , were prepared by melt spinning. EDS data showed that Cu as well as Al atoms are effectively substituted for with Au. The hypercubic lattice parameter of as-quenched samples slowly increases with x, while phonon- and phason-type disorders are not affected by Au substitution. Experimental structure factors for `sum' lines were used to derive an average radius of the atomic hypersurfaces. Comparison of experimental versus calculated ratios of structure factors for different models yielded information about the Au distribution over the icosahedral sites. It was inferred that a fraction of the gold shapes its Al surrounding in a -type configuration. Evidence was found for d - sp hybridization of Au - Al bonds, on the basis of the `white-line' area at the Au absorption edge.

Quantitative EDS analysis in the environmental ESEM using a bremstrahlung intensity-based correction for primary electron beam variation and scatter

Quantitative EDS analysis of bulk samples in the scanning electron microscope (SEM) or electron microprobe requires, as a fundamental parameter, a stable and reproducible primary electron beam current Beam current is usually measured with a Faraday cage positioned in the electron column below the objective aperture or in the specimen holder. Reproducibility and stability within 1%/hour is a minimum condition.Primary beam current measurement in the ESEM or any high pressure SEM is difficult to measure. Electron-gas interaction in the biased chamber generates a positive ion flow highly amplified relative to the primary beam (Danilatos, 1990) and generates an x-ray signal from the gas. The latter signal amplitude is dependent on primary beam current, chamber pressure and backscatter electron signal from the specimen (Griffin et al. 1993). These interactions prevent quantification of EDS data standardised to Faraday cage primary beam current measurements or x-ray counts from a reference standard.

Hg deficiency and phase segregation in HgBa 2CuO 4+δ

HgBa 2CuO 4+δ (Hg-1201) samples synthesized with various initial compositions and at different Hg vapor pressures were examined by SEM, TEM, EDS and X-ray diffraction. The results suggest that Hg-1201 is intrinsically a Hg non-stoichiometry phase. The allowed Hg vapor pressure, which is limited by the competitions from HgBaO 2, required an equilibrium defect density in the Hg site at synthesis temperatures. These defects correspond to a 30% Hg deficiency at ∼800°C with a balance Hg vapor pressure at the order of 10 −1 atm. However, the equilibrium defect density should decrease with temperature, and is approximately zero at room temperature based on our EDS data. Therefore, cation diffusion, defect coarsening, and possible phase segragation occur during the cooling, which create various impurities and inclusions in the samples obtained. Further investigations on the related phase diagrams are needed to design a better synthesis procedure.

Investigation of [(py) (Et) Co(dmg · GaEt 2) 2] and [Ni(dmg · GaEt 2) 2] (py = pyridine; dmg = dimethylglyoximato) as single source precursors for deposition of β-CoGa and NiGa by MOCVD. Crystal structure of [(py)(Et)Co(dmg · GaEt 2)(dmgH)

The complexes [(py)(Et)Co(dmg · GaEt 2) 2], 1, and [Ni(dmg · GaEt 2) 2], 2, (dmg = dimethylglyoxime) were synthesized for study as potential precursors for Metalorganic Chemical Vapor Deposition (MOCVD) of β-CoGa and NiGa. Complex 1 is easily hydrolyzed to [(py)(Et)Co(dmgH)(dmg · GaEt 2)], 3; a single crystal X-ray structure was obtained for this product. Thermogravimetric analyses (TGA) under H 2 flow resulted in a residual mass of 35% at 650°C for 1 (residual for CoGa 2 is 31%) and 29% at 500°C for 2 (residual for NiGa 2 is 36%). The highest peaks in the electron impact MS corresponded to (MWt  py  2C 2H 5) + , 1, and (MWt  C 2H 5) + , 2. The next peaks for both compounds corresponded to loss of the remaining ethyl groups. MOCVD at 560°C resulted in polycrystalline β-CoGa (using 1 as a precursor) and polycrystalline NiGa ( 2). Upon raising the temperature of the GaAs substrate to 630°C, 1 gave films with areas of epitaxial growth in a primarily polycrystalline β-CoGa film; partial degradation of the substrate also occurs. EDS and XPS data showed how film composition can be controlled by precursor design. EDS analysis of the CoGa (1 : 2.4) and NiGa (1 : 2.0) films showed that stoichiometry of the precursors was principally retained. The films exhibit only negligible carbon or nitrogen contamination, but the oxygen content is relatively high (10–20%). XPS data show that oxygen near the surface is bonded to both Co and Ga, but in the film, oxygen is only bonded to Ga.

Toward rapid inorganic phase identification from electron diffraction and EDS data

Toward rapid inorganic phase identification from electron diffraction and EDS data