Metal Silicate Research Articles

Core-shell structured MnSiO3 supported with CNTs as a high capacity anode for lithium-ion batteries.

Metal silicates are good candidates for use in lithium ion batteries (LIBs), however, their electrochemical performance is hindered by their poor electrical conductivity and volume expansion during Li+ insertion/desertion. In this work, one-dimensional core-shell structured MnSiO3 supported with carbon nanotubes (CNTs) (referred to as CNT@MnSiO3) with good conductivity and electrochemical performance has been successfully synthesized using a solvothermal process under moderate conditions. In contrast to traditional composites of CNTs and nanoparticles, the CNT@MnSiO3 composite in this work is made up of CNTs with a layer of MnSiO3 on the surface. The one-dimensional CNT@MnSiO3 nanotubes provide a useful channel for transferring Li+ ions during the discharge/charge process, which accelerates the Li+ diffusion speed. The CNTs inside the structure not only enhance the conductivity of the composite, but also prevent volume expansion. A high reversible capacity (920 mA h g-1 at 500 mA g-1 over 650 cycles) and good rate performance were obtained for CNT@MnSiO3, showing that this strategy of synthesizing coaxial CNT@MnSiO3 nanotubes offers a promising method for preparing other silicates for LIBs or other applications.

Cleaning research on reverse osmosis membranes depth-fouled by transition metal oxides and silicates in ultrasound-assisted organic acids

Cleaning research on reverse osmosis membranes depth-fouled by transition metal oxides and silicates in ultrasound-assisted organic acids

Facile synthesis of metal nanoparticles decorated magnetic hierarchical carbon microtubes with polydopamine-derived carbon layer for catalytic applications.

It is highly desirable but challenging to fabricate a unique hybrid material comprising nanosized copper/cobalt/nickel nanoparticles (NPs) uniformly distributed on magnetic supports. Herein in this work, hierarchical magnetic metal silicate hollow microtubes were prepared using silica coated magnetic N-doped carbon microtubes (NCMTs@Fe3O4@SiO2) as a chemical template; then polydopamine (PDA) was employed to coat onto magnetic metal silicate carbon microtubes (NCMTs@Fe3O4@CuSNTs/CoSNTs/NiSNTs), which can be carbonized to form hierarchical hybrid composites with uniformly-dispersed metallic copper/cobalt/nickel NPs embedded in PDA-derived carbon layers (NCMTs@Fe3O4@SiO2@C/Cu-Co-Ni). Owing to its hierarchical structure, large specific surface area as well as the high density of metal NPs, the resultant NCMTs@Fe3O4@SiO2@C/Ni-Co-Cu could be applied as catalysts towards the reduction of 4-nitrophenol (4-NP). Furthermore, the NCMTs@Fe3O4@SiO2@C/Ni-Co-Cu catalysts could be easily collected and separated by applying an external magnetic field. In particular, it was found that NCMTs@Fe3O4@SiO2@C/Ni exhibited ultra-high catalytic activity on 4-NP reduction in comparison with Cu and Co supported catalysts. In addition, this unique hierarchical structure combined with magnetic recyclability make NCMTs@Fe3O4@SiO2@C/Ni a highly promising candidate for diverse applications.

Photoluminescence properties of a Ce3+ doped Sr3MgSi2O8 phosphor with good thermal stability.

This study mainly reports an investigation about the crystal structure and photoluminescence properties of a Ce3+ doped alkaline earth metal silicate Sr3MgSi2O8. X-ray powder diffraction (XRD) and structure refinement methods are adopted to characterize the phase composition and crystal structure. The excitation/emission spectra and diffuse reflection spectra (DRS) of the title phosphor are measured and the mechanism of concentration quenching as well as thermal quenching are discussed in detail. Results show that the concentration quenching in Sr3MgSi2O8 is due to dipole–dipole interaction energy transfer between Ce3+ ions. The title phosphor has an excellent thermal stability with 90% emission intensity reserve when the temperature rises to 150 °C. The related mechanism is considered to be the thermal ionization effect and an energy level diagram was proposed to show the thermal ionization process.

Tracking Hadean processes in modern basalts with 142-Neodymium

The short-lived Sm146→142Nd isotope system (t1/2=103 Ma) provides constraints on the timing and processes of terrestrial silicate fractionation during the early Hadean. Although some Archean terranes preserve variability in 142Nd/144Nd, no anomalies have been resolved previously in young rocks. This study provides high precision 142Nd/144Nd data on a suite of ocean island basalts from Samoa and Hawaii previously shown to have variable depletions in 182W/184W that are inversely correlated with 3He/4He ratios. Improved analytical techniques and multiple replicate analyses of Nd show a variation in μ142Nd values between −1.3 and +2.7 in the suite, relative to the JNdi standard. Given the reproducibility of the standard (±2.9 ppm, 2 SD), two Samoan samples exhibit resolved variability in their 142Nd/144Nd ratios outside of their 95% confidence intervals, suggesting minor variability in the Samoan hotspot. One sample from Samoa has a higher μ142Nd of +2.7, outside the 95% confidence interval (±1.0 ppm) of the average of the JNdi standard. Limited, but resolved, variation in 142Nd/144Nd within the suite suggests the preservation of early Hadean silicate differentiation in the sources of at least some basalts from Samoa. Larger variations of 182W/184W and 3He/4He ratios in the same samples suggest that metal–silicate separation and mantle outgassing left a more persistent imprint on the accessible mantle compared to 142Nd/144Nd ratios which are impacted by early silicate differentiation.

Inorganic modification of layered silicates toward functional inorganic-inorganic hybrids

After careful investigation on the formation/preparation, the structures and the reactivity of a class of layered alkali silicates (kanemite, makatite, octosilicate, magadiite and so on) in 1960–80', the applications of the layered silicic acids and the alkaline metal silicates have extensively been investigated. The applications of these layered silicates range from the ion exchanger, adsorbent, catalyst and catalysts' support, bio-related one and so on. For the construction of functional nanomaterials, host-guest reaction has been applied to optimize materials performances as well as to find new functions. The functionalization of layered silicates with various organic functional groups has been investigated extensively and summarized in several review papers. In this review article, the functionalization of the layered alkali silicates and the silicic acids derived from with inorganic species will be summarized in order to highlight the present status of the materials chemistry on layered alkali silicates and their hybrids with inorganic species toward the practical application.

Late metal–silicate separation on the IAB parent asteroid: Constraints from combined W and Pt isotopes and thermal modelling

The short-lived 182Hf–182W decay system is a powerful chronometer for constraining the timing of metal–silicate separation and core formation in planetesimals and planets. Neutron capture effects on W isotopes, however, significantly hamper the application of this tool. In order to correct for neutron capture effects, Pt isotopes have emerged as a reliable in-situ neutron dosimeter. This study applies this method to IAB iron meteorites, in order to constrain the timing of metal segregation on the IAB parent body.The ε182W values obtained for the IAB iron meteorites range from −3.61 ± 0.10 to −2.73 ± 0.09. Correlating εiPt with ε182W data yields a pre-neutron capture ε182W of −2.90 ± 0.06. This corresponds to a metal–silicate separation age of 6.0 ± 0.8 Ma after CAI for the IAB parent body, and is interpreted to represent a body-wide melting event. Later, between 10 and 14 Ma after CAI, an impact led to a catastrophic break-up and subsequent reassembly of the parent body. Thermal models of the interior evolution that are consistent with these estimates suggest that the IAB parent body underwent metal–silicate separation as a result of internal heating by short-lived radionuclides and accreted at around 1.4±0.1 Ma after CAIs with a radius of greater than 60 km.

Salvinia inspired fluroine free superhydrophobic coatings

In this work, Salvinia inspired fluorine free superhydrophobic coatings were prepared by incorporating as-prepared metal silicates in silicone resin along with nanosilica, nanotitania and aluminium stearate. Coatings with different composition were prepared and applied by air spray method over precleaned mild steel panel. The superhydrophobicity and stability of coatings were studied. The pristine resin with no pigments and additives showed hydrophobic behaviour with water contact angle (WCA) of 93.5° and tilting angle (TA) of 60°. The WCA increased to 156.8° and TA to 28° with incorporation of metal silicates. Other properties like abrasion, adhesion, water uptake and water vapour permeation were also evaluated.

Synthesis of lithium metal silicates for lithium ion batteries

The lithium metal silicates (Li2MSiO4) (where M=Mn, Fe, and Co) have a great potential in rechargeable lithium ion batteries as polyanion cathodes, due to the immanent merits such as superior electrochemical properties, low cost, and abundance. However, these merits are suffered from lower electrical and ionic conductivities, owing to the effect of poor lithium ion extraction/insertion kinetics. By building hybrid architectures, the integrated composites may afford much promoting activities towards lithium ion batteries compared with the bare ones. Kinds of synthetic methods such as template method, sol-gel method, and hydrothermal method have been successfully applied to prepare lithium metal silicates based compounds and composite materials. In this review, we aim to present a general view of Li2MSiO4 for the recent progress. The relationship between nanoarchitectures and electrochemical performances is discussed. In the end, we also summarize the opportunities and challenges about Li2MSiO4 nanomaterials recently.

High Pressure Experiments on Metal‐Silicate Partitioning of Chlorine in a Magma Ocean: Implications for Terrestrial Chlorine Depletion

AbstractIn the bulk silicate Earth, chlorine is more depleted than other elements with similar volatilities; however, the cause of terrestrial chlorine depletion is not well understood. Two major hypotheses have been proposed to explain this depletion: Incorporation into the Earth's metallic core and escape to space. The former hypothesis can be tested by investigating the partitioning of chlorine between iron‐rich metallic liquids and silicate melts. In this study, we investigated the experimental partitioning of chlorine between iron‐rich metallic liquids and silicate melts at pressures from 4 to 23 GPa and temperatures from 1,650 to 2,400°C using multi‐anvil presses. The results demonstrate that chlorine is moderately to highly lithophile under the experimental conditions. In sulfur‐free experiments, chlorine becomes slightly more siderophile as temperature increases and less siderophile as pressure increases. For sulfur‐bearing experiments, no significant effects of pressure or temperature were observed. Based on these data and thermodynamic considerations, we obtained empirical laws to estimate chlorine partition coefficients between iron‐rich metallic liquids and silicate melts. Under the P‐T conditions that would have controlled metal‐silicate equilibration during core segregation in the Earth, the calculated metal‐silicate partition coefficients for chlorine are much lower than unity. This result suggests that terrestrial chlorine that may have been present in the accreting Earth was not partitioned into its core, supporting that escape to space is the more likely hypothesis. If terrestrial chlorine was lost to space, chlorine depletion may have resulted from the loss of the primordial hydrosphere during the formation of the Earth.

Synthesis of Novel Lithium Metal Silicate and Its Application in Lithium Ion Batteries as a Potential Cathode Material

Synthesis of Novel Lithium Metal Silicate and Its Application in Lithium Ion Batteries as a Potential Cathode Material

An Orthogonal Investigation in Structures and Performances of Vanadium Modified Li2FeSiO4

A series of different vanadium modified carbon coated lithium iron silicate (Li2Fe1-xVxSiO4/C) composites were prepared by sol-gel precursor and solid-state reaction using ammonium metavanadate (NH4VO3) as a vanadium source material. The effects of vanadium content, sucrose amount, sol-gel time and type of carboxylate acid on crystal structure, surface morphology, elemental composition and electrochemical performance of Li2Fe1-xVxSiO4/C composites were investigated through orthogonal design experiments. The initial discharge capacity of the nominal 35% vanadium modified Li2FeSiO4/C, prepared under the optimized conditions (sucrose amount of 80% and sol-gel time of 2 h using citric acid as a pH regulator), reached as high as 216.7 mAh/g (corresponding to 1.30 moles per formula unit) at 0.1C and room temperature. The composite exhibited a mixed Pmn21 and P21 phase with the coexistences of metallic iron (Fe) and lithium silicate (Li2SiO3) as the main impure phases.

Hydrothermal Preparation, Crystal Chemistry, and Redox Properties of Iron Muscovite Clay.

The development of functional materials based on Earth-abundant, environmentally benign compositions is critical for ensuring their commercial viability and sustainable production. Here we present an investigation into the crystal chemistry and electrochemical properties of the muscovite clay KFe2.75Si3.25O10(OH)2. We first report a low-temperature hydrothermal reaction that allows for a significant degree of control over sample crystallinity, particle morphology, and cation distribution through the lattice. A complex sequence of stacking faults is identified and characterized using a combination of Mössbauer spectroscopy and total scattering neutron experiments. We then show the existence of a reversible electrochemical process using galvanostatic cycling with complementary cyclic voltammetry suggesting that the redox activity occurs primarily on the surface of the particles. We conclude by determining that the ability to (de)intercalate Li ions from the material is hindered by the strong negative charge on the transition metal silicate layers, which prevents the displacement of the interlayer K ions. This work calls attention to a hugely Earth-abundant family of minerals that possesses useful electrochemical properties that warrant further exploration.

An Orthogonal Investigation in Structures and Performances of Vanadium Modified Li2FeSiO4

A series of vanadium modified carbon coated lithium iron silicate (Li2Fe1-xVxSiO4/C) composites were prepared by sol-gel precursor and solid-state reaction using ammonium metavanadate (NH4VO3) as a vanadium source material. The effects of vanadium content (x), sucrose amount (y), sol-gel time (t) and type of carboxylate acid on crystal structure, surface morphology, elemental composition and electrochemical performance of Li2Fe1-xVxSiO4/C composites were investigated through orthogonal design experiments. The preparation parameters were optimized to be x=35%, y=80%, t=2 h and use of citric acid as a pH regulator. The initial discharge capacity of 216.7 mAh/g (corresponding to 1.30 moles per formula unit) was achieved at 0.1C and room temperature with the Li2Fe0.65V0.35SiO4/C composite synthesized under the abovementioned optimized condition. A mixed Pmn21 and P21 phase was identified as the main structure, while metallic iron and lithium silicate (Li2SiO3) as the impure phases. The elemental analysis result revealed that 10.7% carbon was introduced. The elemental vanadium was detected by performing energy dispersive X-ray spectroscopic (EDX) analysis.

Contribution of early impact events to metal‐silicate separation, thermal annealing, and volatile redistribution: Evidence in the Pułtusk H chondrite

AbstractThree‐dimensional X‐ray tomographic reconstructions and petrologic studies reveal voluminous accumulations of metal in Pułtusk H chondrite. At the contact of these accumulations, the chondritic rock is enriched in troilite. The rock contains plagioclase‐rich bands, with textures suggesting crystallization from melt. Unusually large phosphates are associated with the plagioclase and consist of assemblages of merrillite, and fluorapatite and chlorapatite. The metal accumulations were formed by impact melting, rapid segregation of metal‐sulfide melt and the incorporation of this melt into the fractured crater basement. The impact most likely occurred in the early evolution of the H chondrite parent body, when post‐impact heat overlapped with radiogenic heat. This enabled slow cooling and separation of the metallic melt into metal‐rich and sulfide‐rich fractions. This led to recrystallization of chondritic rock in contact with the metal accumulations and the crystallization of shock melts. Phosphorus was liberated from the metal and subsumed by the silicate shock melt, owing to oxidative conditions upon slow cooling. The melt was also a host for volatiles. Upon further cooling, phosphorus reacted with silicates leading to the formation of merrillite, while volatiles partitioned into the residual halogen‐rich, dry fluid. In the late stages, the fluid altered merrillite to patchy Cl/F‐apatite. The above sequence of alterations demonstrates that impact during the early evolution of chondritic parent bodies might have contributed to local metal segregation and silicate melting. In addition, postshock conditions supported secondary processes: compositional/textural equilibration, redistribution of volatiles, and fluid alterations.

Stabilization of Lithium Transition Metal Silicates in the Olivine Structure.

While olivine LiFePO4 shows amongst the best electrochemical properties of Li-ion positive electrodes with respect to rate behavior owing to facile Li+ migration pathways in the framework, replacing the [PO4]3- polyanion with a silicate [SiO4]4- moiety in olivine is desirable. This could allow additional alkali content and hence electron transfer, and increase the capacity. Herein we explore the possibility of a strategy toward new cathode materials and demonstrate the first stabilization of a lithium transition metal silicate (as a pure silicate) in the olivine structure type. Using LiInSiO4 and LiScSiO4 as the parent materials, transition metal (Mn, Fe, Co) substitutions on the In/Sc site were investigated by computational modeling via atomic scale simulation. Transition metal substitution was found to be only favorable for Co, a finding confirmed by the successful solid state synthesis of olivine LixInyCo2-x-ySiO4. Stabilization of the structure was achieved by entropy provided by cation disorder.

Design of Polymeric Antiscalants Based on Functional Vinyl Monomers for (Fe, Mg) Silicates

Silica/silicate scaling is one of a few detrimental problems that cause high economical loss in the geothermal and petroleum fields. The prevention of silica/silicate has been attempted using antiscalants with functional groups, particularly –NH2; however, metal silicates are commonly found in the fields and the antiscalants developed so far are not effective against these compounds. In this work, polymeric antiscalants have been developed by merging two or more functional co-monomers consisting of various chelating groups for metal cations. Homo and copolymers of acrylamide (AM), the sodium salt of vinyl sulfonic acid (VSA), and vinyl phosphonic acid (VPA) were synthesized to examine their antiscaling performance against metal-silicate scaling. Lab-scale metal silicates were obtained in a pressured autoclave reactor. The antiscalants were tested at various dosages (25, 50, and 100 ppm), and their effects were investigated from the left over decantates after isolation of the solid precipitates. The polyme...

Porous and Low-Crystalline Manganese Silicate Hollow Spheres Wired by Graphene Oxide for High-Performance Lithium and Sodium Storage.

Herein, a graphene oxide (GO)-wired manganese silicate (MS) hollow sphere (MS/GO) composite is successfully synthesized. Such an architecture possesses multiple advantages in lithium and sodium storage. The hollow MS structure provides a sufficient free space for volume variation accommodation; the porous and low-crystalline features facilitate the diffusion of lithium ions; meanwhile, the flexible GO sheets enhance the electronic conductivity of the composite to a certain degree. When applied as the anode material for lithium-ion batteries (LIBs), the as-obtained MS/GO composite exhibits a high reversible capacity, ultrastable cyclability, and good rate performance. Particularly, the MS/GO composite delivers a high capacity of 699 mA h g-1 even after 1000 cycles at 1 A g-1. The sodium-storage performance of MS/GO has been studied for the first time, and it delivers a stable capacity of 268 mA h g-1 after 300 cycles at 0.2 A g-1. This study suggests that the rational design of metal silicates would render them promising anode materials for LIBs and SIBs.

Recovery of rare earths and aluminum from FCC catalysts manufacturing slag by stepwise leaching and selective precipitation

A stepwise leaching process was developed to recover rare earth elements (REEs) and aluminum (Al) from FCC catalysts manufacturing slag (FCC waste slag), with NaOH and HCl. The FCC waste slag was treated with 2.5mol/L NaOH at 293K for 0.5h to convert 72.4% of Al into NaAlO2. Then, the caustic conversion residue was decompose using 3mol/L HCl to control leaching pH at 1.5 under 293K for 3h. Leaching efficiencies of 94.2%, 98.6% and 98.8% for Al, La and Ce, respectively, were achieved. 98.7% purity of rare earths oxide (REO) product was obtained after further treatments including oxalic acid precipitation and calcination. The filter liquor of oxalic acid precipitation was recycled to acid leaching step to recover the remaining Al. 97.6% REEs and 98.4% Al were recovered in total. Furthermore, the polymerization of metal ions and silicates were found and confirmed by IR and XRD analysis.

Nanocrystalline MgMnSiO4 and MgCoSiO4 particles for rechargeable Mg-ion batteries

Magnesium-ion batteries hold promise as next-generation secondary battery systems owing to its low cost, safety and high volumetric capacity. Magnesium metal silicates exhibit potential electrode materials with high specific capacities. However, the strong electrostatic interaction between Mg2+ and host lattice due to its divalency as well as antisite cation exchange, induces slow intercalation kinetics of Mg ions within the crystal lattices. Thus, nanocrystalline particles with shortened Mg ion diffusion distance enable the insertion/extraction of Mg ions and improve specific capacities of the batteries. Herein, we report the low-temperature production of crystalline MgMnSiO4 and MgCoSiO4 nanoparticles by a rapid supercritical fluid processing. The extraction of magnesium ions from the olivine framework has been confirmed by X-ray photoelectron spectroscopy, revealing its ability as active materials for magnesium-ion battery.