Metal Condensation Research Articles

Hydrothermal Synthesis of Monodisperse Ce0.5Zr0.5O2 Metastable Solid Solution Nanocrystals

AbstractAn environmentally friendly and economically efficient method has been developed to synthesize monodisperse CeO2‐ZrO2 solid solution nanocrystals. In this process, the formation of oleate‐stabilized Ce0.5Zr0.5O2 nanocrystals was designed to proceed through hydrolytic sol–gel condensation of metal–oleate precursors in an aqueous solution and subsequent hydrothermal growth at 200 °C for 6 h. The results showed that the 3.0‐nm‐sized nanocrystals possess a metastable CeO2‐ZrO2 tetragonal phase with well‐designed chemical composition and are nearly monodisperse. Owing to the uniform textural and elemental properties, the products exhibit relatively high thermal stability of the metastable phase and well‐defined reduction properties.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Characterizing Mineral Dusts and Other Aerosols from the Middle East—Part 1: Ambient Sampling

The purpose of the Enhanced Particulate Matter Surveillance Program was to provide scientifically founded information on the chemical and physical properties of dust collected over a period of approximately 1 year in Djibouti, Afghanistan (Bagram, Khowst), Qatar, United Arab Emirates, Iraq (Balad, Baghdad, Tallil, Tikrit, Taji, Al Asad), and Kuwait (northern, central, coastal, and southern regions). Three collocated low-volume particulate samplers, one each for the total suspended particulate matter, < 10 μ m in aerodynamic diameter (PM10) particulate matter, and < 2.5 μ m in aerodynamic diameter (PM2.5) particulate matter, were deployed at each of the 15 sites, operating on a ‘1 in 6’ day sampling schedule. Trace-element analysis was performed to measure levels of potentially harmful metals, while major-element and ion-chemistry analyses provided an estimate of mineral components. Scanning electron microscopy with energy dispersive spectroscopy was used to analyze the chemical composition of small individual particles. Secondary electron images provided information on particle size and shape. This study shows the three main air pollutant types to be geological dust, smoke from burn pits, and heavy metal condensates (possibly from metals smelting and battery manufacturing facilities). Non-dust storm events resulted in elevated trace metal concentrations in Baghdad, Balad, and Taji in Iraq. Scanning-electron-microscopy secondary electron images of individual particles revealed no evidence of freshly fractured quartz grains. In all instances, quartz grains had rounded edges and mineral grains were generally coated by clay minerals and iron oxides.

Phosphorus-bearing sulfides and their associations in CM chondrites

Phosphorus-bearing Fe and Ni sulfides represent a new type of phosphorus compounds and are characteristic accessory phases of CM chondrites. The proportions of atoms in the sulfides can be approximated by the equation (Fe + Ni)/P = 0.965 ± 0.003 (1σ) · S/P + 1.255 ± 0.036 (1σ). Sulfides with high S/P ratios are systematically richer in Fe and poorer in Ni compared with low-S/P sulfides. Their characteristic minor elements are Cr, Ca, Co, K, and Na. The contents of Cr and Ca may reach several weight percent, but their incorporation does not affect the relation between (Fe + Ni)/P and S/P. This is also true of light elements (O and H), which probably occur in the P-bearing sulfides in certain amounts. The sulfides are usually associated with schreibersite, barringerite, eskolaite, and daubreelite. A negative correlation was observed between the Fe/Ni ratios of coexisting P-bearing sulfides and phosphides. Metallic iron was never found in association with the sulfides. It can be suggested that P-bearing sulfide is a primary phase rather than a secondary alteration product formed under the conditions of the CM chondrite parent body. This phase had to be stable in the solar nebula after the formation of Ca-Al inclusions and before the condensation of Fe-Ni metal. At high temperatures, P-bearing sulfide with low Fe/Ni and S/P ratios coexists with schreibersite in the solar gas. During condensation schreibersite is replaced by barringerite, which is accompanied by a decrease in the Fe/Ni ratio of phosphides and an increase in the S/P and Fe/Ni ratios of P-bearing sulfides. Trace element data suggest that the P-bearing sulfides could be formed in the solar nebula by the sulfidization of a precursor phase of extrasolar origin.

Physical characteristics of very small meteoroids

We have optically recorded faint meteors using a large aperture LLLTV (low light level television) system based on second generation image intensifiers. These data consist of 42 two-station meteors of which 13 were captured during an observing campaign near London, Ontario (Canada) in May 2004, and 29 during a campaign near Kiruna (Sweden) in October 2007. Among 13 meteors recorded in the London campaign, where the baseline between the two sites was 5 km, only four meteors satisfied our requirement for complete lightcurves and deceleration profiles by starting in the field of view, of at least one station and also ending in the field of view of at least one station. From the second set of 29 meteors captured in Sweden, with a baseline of 117.7 km, only two satisfied these criteria. The cameras used in both campaigns had fields of view of 6 degrees, which with an assumed range of 100 km, gives a scale of 13 m/pixel at ∼60 interlaced fields per second. This resolution allows precise measurement of the deceleration of very faint meteors. The limiting magnitude for meteors on these systems is near V =+ 8, while +11th magnitude stars are visible in the individual fields. The meteors detected in these two campaigns have peak brightnesses between absolute magnitude +6.2 and +7.4. Their photometric masses range from 4.2 mg to 0.35 mg. An ablation model was applied to fit each complete two-station event using the high-precision metric and photometric data as a constraint, in an attempt to compute bulk meteoroid densities. Interestingly, a large proportion of our faint meteor events were found to ablate at low altitudes, a result partly of our observing biases. The orbits of these events are consistent with either asteroidal or a Jupiter-family comet origin. The meteoroids’ physical properties, as determined through model fits, suggest high densities, which favors an asteroidal interpretation. The high percentage of apparently dense asteroidal meteoroids at these small sizes may call into question earlier findings that only ∼1% of meteoroids at these masses are asteroidal in origin. Our results are similar to others that find ∼15% of faint TV meteors had spectra consistent with pure iron meteoroids. We find that many of these apparently asteroidal objects also undergo extensive fragmentation, which may reflect melting and spraying of droplets rather than mechanical fragmentation. Some individual cases in our small dataset will be highlighted where high bulk densities (approaching that of iron) are required to adequately match the end height, peak brightness, and observed deceleration. We speculate that these meteoroids may represent metallic condensates from impact-processed asteroid regolith.

Synthesis and Characterization of Yttrium-doped Core-Shell SiO2Nanoparticles by Reverse Micelle and Sol-gel Processing

In this study, yttrium-doped SiO₂ nanoparticles are synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. Spherical Y-doped SiO2 nanoparticles with a uniform size distribution are prepared using selfassembly molecules in conjunction with the hydrolysis and condensation of organometallic precursors. The water/surfactant molar ratio influenced the Y-doped SiO₂ particles distribution of the core-shell composite particles and the distribution of Y doped SiO₂ particles was broadened as the water to surfactant ratio increased. The particle size of Y increase linearly as the Y(NO₃)₃ solution concentration increased. The average size of the cluster was found to depend on the micelle size, the nature of the solvent, and the concentration of the reagent. The effects of synthesis parameters, such as the molar ratio of water to surfactant and the molar ratio of water to TEOS, are discussed.

Exciton Gas Compression and Metallic Condensation in a Single Semiconductor Quantum Wire

We study the metal-insulator transition in individual self-assembled quantum wires and report optical evidence of metallic liquid condensation at low temperatures. First, we observe that the temperature and power dependence of the single nanowire photoluminescence follow the evolution expected for an electron-hole liquid in one dimension. Second, we find novel spectral features that suggest that in this situation the expanding liquid condensate compresses the exciton gas in real space. Finally, we estimate the critical density and critical temperature of the phase transition diagram at n{c} approximately 1 x 10;{5} cm;{-1} and T{c} approximately 35 K, respectively.

Platinum-Group Elements in Cosmochemistry

Research Article| August 01, 2008 Platinum-Group Elements in Cosmochemistry Herbert Palme Herbert Palme *Institut für Geologie und Mineralogie, Universität zu Köln Zülpicherstrasse 49b, 50674 Köln, Germany E-mail: herbert.palme@uni-koeln.de Search for other works by this author on: GSW Google Scholar Elements (2008) 4 (4): 233–238. https://doi.org/10.2113/GSELEMENTS.4.4.233 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Herbert Palme; Platinum-Group Elements in Cosmochemistry. Elements 2008;; 4 (4): 233–238. doi: https://doi.org/10.2113/GSELEMENTS.4.4.233 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyElements Search Advanced Search Abstract In a cooling solar nebula, five of the six platinum-group elements (PGE) condense as refractory-metal alloys at temperatures above the condensation of Fe-Ni metal. Non-refractory Pd condenses in solid solution with Fe-Ni. Such refractory alloys are preserved in some meteorites, although they are often highly altered. The high resistance of PGE to oxidation leads to efficient extraction with metallic Fe-Ni during metal segregation and core formation. Experimentally determined PGE metal-silicate partition coefficients predict lower contents of PGE in planetary silicates than are found, supporting a late addition of PGE components. PGE are particularly useful as tracers of impacting extraplanetary materials in the strongly PGE-depleted crusts of the Earth and other planets. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Synthesis and characterization of CeO 2-doped SiO 2 nanoparticles by a reverse micelle and sol–gel processing

CeO 2-doped SiO 2 nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of TEOS within the micro-emulsion. Average particle sizes of CeO 2-doped SiO 2 were found in the range 15–35 nm. The effects of synthesis parameters such as the molar ratio of water to tetraethyl orthosilicate (TEOS) and the molar ratio of water to surfactant are discussed.

Physical and Chemical Characterization of Airborne Particles from Welding Operations in Automotive Plants

Airborne particles were characterized from six welding operations in three automotive plants, including resistance spot welding, metal inert gas (MIG) welding and tungsten inert gas (TIG) welding of aluminum and resistance spot welding, MIG welding and weld-through sealer of galvanized steel. Particle levels were measured throughout the process area to select a sampling location, followed by intensive particle sampling over one working shift. Temporal trends were measured, and particles were collected on filters to characterize their size and chemistry. In all cases, the particles fell into a bimodal size distribution with very large particles >20 μm in diameter, possibly emitted as spatter or metal expulsions, and very small particles about 1 μm in diameter, possibly formed from condensation of vaporized metal. The mass median aerodynamic diameter was about 1 μm, with only about 7% of the particle mass present as ultrafine particles <100 nm. About half the mass of aluminum welding particles could be accounted for by chemical analysis, with the remainder possibly present as oxygen. Predominant species were organic carbon, elemental carbon, iron, and aluminum. More than 80% of the particle mass could be accounted for from steel welding, primarily present as iron, organic carbon, zinc, and copper. Particle concentrations and elemental concentrations were compared with allowable concentrations as recommended by the Occupational Safety and Health Administration and the American Conference of Governmental Industrial Hygienists. In all cases, workplace levels were at least 11 times lower than recommended levels.

Effects of ion beam treatment on atomic and macroscopic adhesion of copper to different polymer materials

Low-energy ion irradiation of polymer induces different phenomena in the near surface layer, which effect strongly the metal–polymer interface formation and promotes adhesion of polymers to metals. Low-energy argon and oxygen ion beams were used to alter the chemical and physical properties of different polymers (PS (polystyrene), PαMS (poly(α-methylstyrene), BPA-PC (bisphenol-A-polycarbonate) and PMMA (poly(methyl methacrylate)), in order to understand the adhesion phenomena between a deposited Cu layer and the polymers. The resulting changes were investigated by various techniques including X-ray photoelectron spectroscopy, measurements of the metal condensation coefficient and a new technique to measure cross-linking at the polymer surface. Two types of practical adhesion strengths of Cu–polymer systems, measured using 90° peel tests, were observed: (i) peel strength increased at low ion fluences, reached a maximum and then decreased after prolonged treatment and (ii) no improvement in the peel strength on treated polymer surfaces was recorded. The improvement in the metal–polymer adhesion in the ion fluence range of 10 13–10 15 cm −2 is attributed to the creation of a large density of new adsorption sites resulting in a larger contact area and incorporation of chemically active groups that lead to increased interaction between metal and polymer by metal–oxygen–polymer species formation. XPS analysis of peeled-off surfaces showed that in most cases the failure location changed from interfacial for untreated polymers to cohesive failure in the polymer for treated surfaces. These observations and measurements of the metal condensation coefficients suggest that bonding is improved at the metal–polymer interface for all metal–polymer systems. However, the decrease in the peel strength at high ion fluences is attributed to the formation of a weak boundary layer in polymers. The correlation between sputter rate of polymers and altering in the peel strength for moderate ion fluences was determined. It was observed that the metal–polymer adhesion could be improved for PS and BPA-PC, which have a low sputter rate and preferentially formed cross-links in the treated surface. For degrading polymers, like PαMS and PMMA, chain scission rather than cross-linking dominates, low molecular weight species are formed and no adhesion enhancement is observed.

Isotopic fractionation of germanium in iron meteorites: Significance for nebular condensation, core formation and impact processes

The siderophile and volatile nature of germanium allow Ge isotopes to be used to investigate the early history of planetesimals, by tracing processes of core formation and impact through the study of magmatic and non-magmatic iron meteorites. Germanium isotopic compositions were measured using a hexapole-collision cell MC-ICPMS, with an external reproducibility of 0.06‰/amu. Iron meteorites display heavy Ge isotopic compositions ( δ 74Ge = δ 74Ge/ 70Ge = − 0.27 to + 1.92‰) with respect to a JMC Ge standard, which contrast with the light isotopic compositions of the studied terrestrial materials (Aldrich Ge standard: δ 74Ge = − 1.68 − − 1.72 ± 0.22‰; sphalerite: δ 74Ge = − 0.69‰). All the data fall on the theoretical mass fractionation line, indicating no isotopic anomalies. The samples from magmatic irons (IIA–IIB, IIIAB, IIC) have relatively homogeneous Ge isotopic compositions of δ 74Ge = 1.77 ± 0.22‰ (2 σ) for a large range of Ge contents (36–189 ppm). In contrast, the samples of the non-magmatic groups (IAB, IIE) have lower and more variable Ge isotopic compositions, with δ 74Ge = 1.15 ± 0.20‰ for IAB Group (Ge = 254–493 ppm), δ 74Ge = − 0.27 to + 0.43‰ for IIE Old group (Ge = 63–69 ppm), and δ 74Ge = + 1.40 ± 0.22‰ for the Watson sample (Ge = 50 ppm) from the IIE Young group. Except for IIE samples, no within-group correlation of δ 74Ge with Ir or Ge contents is observed, demonstrating that fractional crystallization or crystal segregation do not fractionate Ge isotopes. The lack of inter-group correlation between the Ge isotopic composition of magmatic irons and Ni content, an indicator of redox processes, suggests that if Ge isotopes are fractionated by redox-induced diffusion during metal-silicate segregation, isotopic equilibration towards the initial composition must also occur during isotopic exchange at high temperature. Thus the average δ 74Ge value of 1.77 ± 0.22‰ should be representative of their parent body precursors. The lack of correlation between the Ge isotopic composition and Ge/Ni ratios, and the high Ge/Ni ratio of IIA samples (> Ge/Ni in CI chondrites) may reflect the high proportion of metal condensates present in the parent body, before metal-silicate differentiation. These metal phases would carry the Ge isotopic signature of a Ge-enriched gas phase of the solar nebula. For the IAB non-magmatic group, the light and homogeneous Ge isotopic composition may result from condensation from a 70Ge-enriched vapour subsequent to partial melting within a porous parent body. The origin of the heating event, 26Al-decay or impact on the surface of the chondritic body, cannot be distinguished. In contrast, it can be demonstrated that impact events are involved in the formation of IIE irons: the negative δ 74Ge–Ge correlation with increasing δ 74Ge values from the Old group to the Watson sample of the Young group would result from non-Rayleigh evaporation of 70Ge during impact, with gas–melt back-reaction. The high δ 74Ge of the Watson sample (Young group) is consistent with successive impacts on the surface of the IIE parent body. The very light Ge isotopic composition of the Old, less impacted IIE irons compared to other studied iron meteorites suggests a light Ge isotopic composition for the IIE parent body.

Cryochemistry of nanometals

The main scope of the work is to combine the unique properties of metal atoms, clusters and nanoparticles with different organic and inorganic substances, particularly polymers and liquid crystals using methods of cryochemistry. The joint and layer-by-layer condensation of metal (Ag, Mg, Cu, Pb, Sm and Eu) and different active and inert organic and inorganic compounds vapors on the cooled surfaces at 10–300K have been made. The problems of stabilization and of activity and selectivity in competitive reactions of metal species are discussed.

Synthesis and characterization of Ag/Pd doped SiO2 nanoparticles by a reverse micelle and sol–gel processing

Ag–Pd doped SiO2 nanoparticles have been synthesized within reverse micelle via metal alkoxide hydrolysis and condensation. The size of the particles can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of TEOS within the microemulsion. The average size of synthesized particles was about in the size range of 5–20nm and Ag–Pd particles 1–5nm. The effects of synthesis parameters, such as the concentration of Ag/Pd solution, the molar ratio of water to TEOS, and the molar ratio of water to surfactant, are discussed.

Experimental study of metallic iron condensation in vacuum

Experimental study of metallic iron condensation in vacuum

Synthesis and Microstructure of TiO&lt;sub&gt;2&lt;/sub&gt;-SiO&lt;sub&gt;2&lt;/sub&gt; Nanoparticles by a Reverse Micelle and Sol-Gel Processing

TiO2-SiO2 nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles can be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TIP) within the micro-emulsion. The average size of synthesized TiO2-SiO2 nanoparticles was about in the size range of 20-100 nm. The effects of synthesis parameters, such as the molar ratio of water to precursor and the molar ratio of water to surfactant, are discussed.

Silica Encapsulation of Hydrophobically Ligated PbSe Nanocrystals

Spherical PbSe@SiO2 nanoparticles have been successfully synthesized within reverse micelles via metal alkoxide hydrolysis and condensation within a microemulsion system. These core-shell nanoparticles were characterized by transmission electron microscopy (TEM), NIR absorption spectroscopy, energy-dispersive X-ray analysis, and TEM electron diffractions. It shows that the obtained core-shell structures have a spherical shape with narrow size distribution (average size approximately 35 nm) and smooth surfaces. The size of the particles and the thickness of the shells can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethoxysilane (TEOS) within the microemulsion.

Fabrication and Microstructure of ZnO-SiO&lt;sub&gt;2&lt;/sub&gt; Nanoparticles by a Reverse Micelle and Sol-Gel Processing

ZnO-SiO2 nanoparticles were synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles was controlled by manipulating the relative rates of the hydrolysis and condensation reaction of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The average size of synthesized ZnO-SiO2 nanoparticles was in the range of 20-40 nm. The effects of synthesis parameters such as the molar ratio of water to precursor and the molar ratio of water to surfactant are discussed.

Origin of chondritic forsterite grains

Iron-poor and refractory lithophile element (RLE) rich forsterite grains occur in all major types of unequilibrated chondrites. In our laser ablation inductively coupled mass spectrometry (LA-ICPMS) minor and trace element study we show that refractory forsterites (RF) from carbonaceous (CC), unequilibrated ordinary (UOC) and a Rumuruti chondrite (RC) have similar chemical compositions with high RLE concentrations and low concentrations of Mn, Fe, Co and Ni. Fractionation of RLEs and rare earth elements (REEs) is in agreement with formation by crystallization from a RLE rich silicate melt. Low concentrations and the fractionation of moderately siderophile elements (Fe, Co, Ni) in RFs suggests formation at low oxygen fugacity, possibly in equilibrium with primitive Fe,Ni metal condensates in a gas of solar composition. Anomalously high Ti in the parental melt can be explained by Ti 3+/Ti 4+ ∼1.5, supporting formation of RF in highly reducing conditions. Low Mn concentrations indicate formation at high temperatures (>∼1160 K). The model of formation of RFs and the accompanying physico-chemical conditions during their formation as well as their relation to non refractory olivine are discussed.

Tailoring of the PS surface with low energy ions: Relevance to growth and adhesion of noble metals

Ion–polymer interaction induces different phenomena in the near surface layer of polymers, and promotes its adhesion to metals. Using XPS, TEM and AFM, polystyrene surface was examined after 1keV ion-beam treatments with oxygen, nitrogen and argon ions in the ion fluence range from 1012 to 1016cm−2 to clarify the following points: chemical reaction after treatment in vacuum and after exposure to air, identification of adsorption-relevant species for metal atoms, formation of cross-links in the outermost polymer layer. The early stages of metal–polymer interface formation during metallization play a crucial role in the metal–polymer adhesion. Therefore, the influence of the ion fluence and ion chemistry on the condensation of noble metals, film growth and peel strength were measured. The peel strength showed a maximum at a certain fluence depending on ion chemistry. For example, the surface treatment with very low fluence of oxygen ions improved the adhesion between copper and polystyrene by two orders of magnitude without significantly increasing the surface roughness measured with AFM. The locus of failure changed at the same time from interfacial failure for untreated polymer surfaces to cohesive failure in the polymer for modified surfaces. A multilayer model of the metal–polymer interface after ion treatment is suggested.

Characterization of Arc Generated Plasma Interactions with a Liquid Metal Medium

Plasma interaction with first wall and interior reactor chamber components is an influencing factor in the design of inertial fusion facilities. The concept of a liquid metal wall, in which a circulating lithium curtain would be used, has been considered in many studies. The interaction of plasmas with moving liquid metals is a complex subject due to the influence of hydrodynamics, evaporation and droplet formation, nucleation and agglomeration of condensed particulates. To gain an understanding of some of the specific details of this interaction an experimental setup of an arc-generated plasma interacting with a liquid lead pool has been designed, constructed and operated. This simulation of the plasma-liquid interaction focuses on the particle condensation of the liquid metal after plasma interaction. The experiment generates transient high-density plasma over 50 μs pulse duration. Plasma characteristics are determined by various diagnostics. A set of collection substrates are arranged to collect nucleated particulates condensing from the evolving plume. Particulate size and distribution are analyzed numerically using digital images.