Zinc Silicate Research Articles

Preparation of Zn(Cd)O:Ga–SiO2 composite scintillating materials

Composite material consisting of highly luminescent Zn(Cd)O:Ga powder embedded in the silica matrix was prepared. It was found out that ZnO:Ga with less developed crystals (i.e. annealed at lower temperatures) is more prone to interact with the SiO2 matrix and form zinc silicates, which in turn resulted in the decrease in the excitonic emission. Pre-annealing of the powders at temperatures above 600 °C prevented the interaction with the SiO2 matrix. ZnO:Ga with well-developed crystals at such a high temperatures was not affected by the matrix and retained its properties, i.e. high radioluminescence intensity and ultrafast sub nanosecond photoluminescence decay. Introducing Cd into the ZnO lattice caused observable red shift in the excitonic luminescence, without negatively affecting the total intensity or the decay.

Light scattering and optical diffusion from willemite spherulites

Willemite is a zinc silicate mineral used in modern day pottery as a decorative feature within glazes. It is produced by controlled heat treatment of zinc oxide-containing ceramic glazes. The heat-treated glazes devitrify, producing thin nanoscale needle-like willemite crystals growing in spherulitic morphologies through branching of the needles. We show here that this resulting morphology of willemite crystals in an inorganic glass matrix has a previously unreported strong interaction with light, displaying remarkable optical diffraction patterns. Thin sections of such spherulites act as optical diffusers, enabling light beams to be spread up to 160° in width. Analysis of the interaction between the willemite spherulites and light suggests that the high density of willemite crystals in the spherulites and the length scales associated with both the thickness of the needles and the spacings between branches are together responsible for this optical diffusion behaviour.

Synthesis of mesoporous MFI zeolite by dry gel conversion with ZnO particles and the catalytic activity on TMB cracking

A facile synthesis method for mesoporous MFI zeolite (MMZ) has been developed. MFI zeolite was synthesized by a dry gel conversion in the presence of ZnO nanoparticles with a size of 20 nm. The as-synthesized MFI zeolite included crystalline layered zinc silicate and already possessed 5–15 nm mesopores. After calcination, MMZ/zinc silicate composite was treated with hydrochloric acid to remove unreacted ZnO particles. The micropore (1–2 nm) volume was increased after the HCl treatment, suggesting that ZnO nanoparticles (1–2 nm) remained during crystallization as well as zinc silicate. The catalytic activity of MMZ on 1,3,5-trimethylbenzene (TMB) cracking was compared with that of conventional MFI nanocrystals with a size of 80–100 nm. The conversion of TMB on MMZ was much higher than that on the MFI nanocrystals even though crystal size of MMZ is larger than the conventional MFI zeolite. These results suggest that acid sites on the internal surface of mesopores of MMZ contribute to the high conversion of TMB.

Synthesis and optical properties of europium doped zinc silicate prepared using low cost solid state reaction method

This paper presents a study on synthesis and optical properties of Zn2SiO4:1 wt% Eu3+ at different heat treatments. The objective of the research is to synthesize Zn2SiO4:1 wt% Eu3+ phosphor by using low cost solid state reaction method with recycled waste bottle glasses as the silicate source. The X-ray diffraction results showed that the prepared Zn2SiO4:1 wt% Eu3+ phosphors have a sharp diffraction peak as the heat treatment temperatures were increased from 600 to 1000 °C. Furthermore, the morphology from the Field emission scanning electron microscope analysis were shown the formation of well crystalline samples with dense packed grains due to the increment of heat treatment temperatures. Fourier transform infrared spectra has confirmed the present elements in Zn2SiO4:1 wt% Eu3+ phosphors while the narrow width of Raman line spectra were observed at temperatures ranging from 700 to 1000 °C indicates good homogeneity and crystallinity of synthesized powders. In addition, the energy band gap of europium doped zinc silicate increased dramatically up to 3.62 eV at temperature of 1000 °C. Photoluminescence measurements has also exhibited the red emission corresponding to the 5D0 → 7F2 (600 nm) when viewed under blue excitation.

Interfacial Reaction-Driven Formation of Silica Carbonate Biomorphs with Subcellular Topographical Features and Their Biological Activity.

We report the interfacial reaction-driven formation of micro/nanostructured strontium carbonate (SrCO3) biomorphs with subcellular topographical features on strontium zinc silicate (Sr2ZnSi2O7) biomedical coatings and explore their potential use in bone tissue engineering. The resulting SrCO3 crystals build a well-integrated scaffold surface that not only prevents burst release of ions from the coating but also presents nanotopographical features similar to cellular filopodia. The surface with biomorphic crystals enhances osteoblast adhesion, upregulates the alkaline phosphatase activity, and increases collagen production, highlighting the potential of the silica carbonate biomorphs for tissue regeneration.

New Water Treatment Chemical PFZSS Preparation and Application

Nowadays global water quality pollution has become extremely serious, and solving water pollution has been extremely urgent, so researches on water pollution solutions have become even urgent. And flocculating method is the most traditional water purification method, research and create new high performance flocculating agent is one of flocculating method inherent problems. The paper mainly describes adding iron, zinc two kinds of metal captions together in polysyllabic acid, well controlling all aspects requirements in technology, researching and creating new water purification substance—poly iron and zinc silicate sulfate flocculants (PFZSS). PFZSS making method is weighting proper amount sodium silicate into container, and meanwhile putting it into water to dissolve, then utilizing dilute euphoric acid and sodium hydroxide to adjust silicic acid solution pH value and arrive at regulated scope, letting it to activate and arrive at certain time, slowly importing activated proper silica acid solution into moderate iron sulfate and zinc sulfate on the condition of fully blending, and finally putting and curing for a while. And implement experiment research on how mixed solution metal cations matching; making method, pH value, and silicon dioxide concentration these factors affect PFZSS overall performance. PFZSS application mainly takes catering industry sewage solution as an example to get PFZSS has very strong absorption capacity, owns good cleaning effects on extremely turbid catering industry treatment sewage COD and turbidity acquiring, its reaction formed flock density is great, sedimentation rate is very fast, so PFZSS will have great application prospects in the aspect of treating urban sewage.

Studies on thermo-optic property of chitosan–alizarin yellow GG complex: a direction for devices for biomedical applications

The optical parameters including the refractive index (n) and thermo-optic coefficient, TOC (dn/dT), the dielectric constant (ε) and its variation with temperature, and the thermal volume expansion coefficient (β) and its variation with temperature of chitosan–alizarin yellow GG (CS–AY GG) complex were examined. The dn/dT and ε-values for the polymer derivative were in the range −2.5 × 10−4 to 1.2 × 10−4°C−1 and 2.2 to 2.3, respectively. The dn/dT values were larger than that of inorganic glasses such as zinc silicate glass (5.5 × 10−6°C−1) and borosilicate glass (4.1 × 10−6°C−1) and were larger than that of organic polymers such as polystyrene (−1.23 × 10−4°C−1) and PMMA (−1.20 × 10−4°C−1). The ε-values are lower than optically estimated ε-values of conventional polymer (3.00), aliphatic polyimide (2.5) and semi-aromatic polyamide (2.83). The obtained results of chitosan derivative are expected to be useful for optical switching and optical waveguide areas for devices of biomedical applications.

The chemical structure of the ZnO/SiC heterointerface as revealed by electron spectroscopies

ZnO layers were deposited on 6H-SiC single crystalline wafers by radio frequency magnetron sputtering. The chemical structure of the ZnO/SiC interface was studied by x-ray photoelectron and x-ray excited Auger electron spectroscopy. A complex chemical structure, involving not only silicon–carbon and zinc–oxygen bonds but also silicon–oxygen and zinc–silicon–oxygen bonds was revealed to form at the ZnO/SiC interface. Based on the comparison with the presumably inert (i.e. chemically abrupt) ZnO/Mo interface, it was concluded that a willemite-like zinc silicate (i.e. Zn2SiO4) interface species develops between ZnO and SiC. The presence of this species at the ZnO/SiC interface will affect the electronic structure of the heterojunction and thus needs to be considered for device optimization.

Effect of 750 keV Argon ion irradiation on nc ZnO[sbnd]SiOx thin films

Nanocomposite (nc) ZnOSiOx thin films were grown using rf magnetron sputter deposition technique and post-deposition annealing at 750°C. These films were irradiated with 750keV Argon ions at fluences in the range from 1×1015 to 1×1017ions/cm2, using Low Energy Ion Beam Facility (LEIBF) at IUAC. X-ray diffraction (XRD) patterns of the as-deposited irradiated films show decrease in intensity of ZnO peaks relative to pristine film. Fourier transform infrared (FT-IR) spectroscopy measurements of the as-deposited irradiated films indicate the breakage of ZnO, ZnOSi and SiOSi bonds in them, which is substantiated by FT-IR measurements of 750°C annealed films that were irradiated at a fluence of 1016ions/cm2. Photoluminescence (PL) measurements show drastic decrease of visible PL emission from as-deposited irradiated films. Current−Voltage (I–V) measurements show decrease in surface resistance of irradiated films by three orders of magnitude. The results suggest that 750keV argon ion irradiation of nc ZnO−SiOx films has resulted in the formation of non-radiative defects in ZnO phase and damage in SiOx, and amorphization in Zinc silicate phase. These results are explained on the basis of the dominant energy loss mechanism of low energy ions in materials.

Effect of crystallographic phase on green and yellow emissions in Mn-doped zinc silicate nanoparticles incorporated in silica host matrix

Silica host matrix reached by manganese-doped zinc silicate nanoparticles (SiO2/Zn2SiO4:Mn) were in-situ synthesized by a sol–gel process. In our approach, we synthesis ZnO:Mn nanoparticles in supercritical conditions of ethanol. After the incorporation of these nanoparticles in silica host matrix, a heat treatment at 1200°C and 1500°C for 2h was performed for the elaboration of SiO2/Zn2SiO4:Mn nanocomposites. Then, these samples were characterized by various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photoluminescence (PL). These samples exhibit broad green and yellow PL bands depending on synthesis temperature. The SiO2/Zn2SiO4:Mn prepared at 1200°C exhibit a green emission centered at about 525nm while the yellow emission centered at 575nm resulted from SiO2/Zn2SiO4:Mn prepared at 1500°C. These two emissions are originated from internal transition in Mn2+ ion doped zinc silicate nanoparticles and the emission wavelength is correlated to the local crystalline field which is fixed by the crystallographic phase.

Effects of Sodium Citrate on the Ammonium Sulfate Recycled Leaching of Low-Grade Zinc Oxide Ores

AbstractThe effects of sodium citrate on ammonium sulfate recycled leaching of low-grade zinc oxide ores were studied. By applying various kinds of detection and analysis techniques such as chemical composition analysis, chemical phase method, scanning electron microscopy and energy dispersive spectrum (SEM/EDS), X-ray diffraction (XRD) and Fourier-transforming infrared spectrum (FT-IR), zinc raw ore, its leaching slag and the functional mechanism of sodium citrate were investigated. Based on a comprehensive analysis, it can be concluded that in contrast to hemimorphite (Zn4Si2O7(OH)2 · H2O), amorphous smithsonite (ZnCO3) and zinc silicate (Zn2SiO4) prove to be refractory phases under ammonium sulfate leaching, while sodium citrate has a better chelating action with the refractory phases, resulting in a higher zinc leaching rate. Under conditions of [NH3]/[NH3]T molar ratio being 0.5, [NH3]T being 7.5 mol/L, [Na3C6H5O7] being 0.2 mol/L, S/L ratio being 1:5, temperature being 303 K, holding time being 1 h in each of the two stages, and stirring rate being 300 rpm, the leaching rate of zinc reached 93.4%. In this article, sulfate ammonium recycled technology also reveals its unique advantage in processing low-grade zinc oxide ores accompanied by high silicon and high alkaline gangue.

Low-Temperature Sintering and Microwave Dielectric Properties of Zn2SiO4 Ceramic Added with Crystalline Zinc Borate

The physical and dielectric properties of composites of known microwave materials, Zn2SiO4 and Zn3B2O6, prepared by solid-state reaction, were investigated with the purpose of developing a low-loss dielectric material for low-temperature co-fired ceramic applications. An off-stoichiometric phase of Zn2SiO4 with extra SiO2 was used to avoid the occurrence of unreacted ZnO. During sintering, zinc borate was found to partially react with residual SiO2 to form Zn2SiO4. The residual zinc borate was converted to a boron-rich glassy phase which helped to reduce the sintering temperature of the composite. Good relative sintering density (>90%) at temperatures below the melting temperature of zinc borate is indicative of a sintering mechanism of diffusion-based mass transfer. Composites containing 15 wt.% zinc borate, 2.5 wt.% lithium carbonate and 20 wt.% zinc borate in zinc silicate had dielectric constants of 6.8 and 6.1, quality factors (Q×f) of 48,800 and 94,300 GHz when sintered at 900°C and 950°C, respectively. These quality factor results are close to the best values reported for zinc silicate at these sintering temperatures.

A Simple Method for Nanostructure Engineering of Mesoporous Zinc Silicate Particles

We report a novel method to engineer a nanostructure of zinc silicate particles. In this method, a mixture of tetraethoxysilane, zinc acetate, and cetyltrimethylammonium chloride (CTAC) was reacted in water at 80 °C for ∼3 h, followed by calcination. This method produced mesoporous zinc silicate particles with a core–shell structure in which the core contained a mixed oxide of ZnO and SiO2, whereas the shell was pure SiO2. We found a faster formation of mixed oxide than pure SiO2, which is believed to be responsible for the core–shell structure. On the basis of this understanding, we engineered the nanostructure of the synthesized particles: (1) zinc oxide in the core was dissolved by citrate buffer to produce hollow mesoporous silica particles, and (2) a layer-by-layer deposition technique was used to grow mesoporous shells on the existing particles, producing multishell mesoporous particles with various morphologies. Using a nitrogen sorption method, the average pore diameter of mesoporous zinc silicate particles was found to be 3.4 nm, which is similar to the diameter of spherical CTAC micelles. We also tested the adsorption capacity of hollow mesoporous silica particles using water-soluble anionic (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt) and cationic (rhodamine B) dyes, and we found a high adsorption capacity for the cationic dye but negligible adsorption for the anionic dye. Finally, we compared release profiles of rhodamine B from hollow mesoporous silica particles with different morphologies.

Photoconversion from yellow-to-green in vanadium doped zinc silicate nanophosphor material

We report a novel synthesis process of V doped β-Zn2SiO4 green nanophosphors based on sol–gel method. After the incorporation of ZnO:V nanoparticles in a silica monolith using a sol–gel method with supercritical drying of ethyl alcohol in two steps, it is heated in air at 1500°C for 2h. X-ray diffraction (XRD) and transmission electron microscopy (TEM) are used to characterize the phase purity, particle size and morphology. In addition, photoluminescence (PL) is used for optical studies. XRD results indicate that pure phase of β-Zn2SiO4 with triclinic structure was obtained after thermal treatment at 1500°C. The PL shows an new intensive luminescence band in the visible range centered at about 526nm, attributed to vanadium in the interfaces between the Zn2SiO4 nanoparticles and the SiO2 host matrix.

Easy emission-color-control of Mn-doped zinc silicate phosphor by use of pH and supercritical water conditions

Emission of Zn2SiO4:Mn2+ can be readily controlled to have continuously variable colors between green and yellow by adjusting the pH of the starting solutions in supercritical water syntheses. Mostly single phase β-Zn2SiO4:Mn2+ exhibiting yellow emission was formed at a pH of 10.5. By changing pH of the starting solution from low values (ca. 2.8) to high values (ca. 12.5), emission color could be proportionally varied from green emission to yellow emission because the amount of each phase was found to change. The selectivity of α- and β-Zn2SiO4 crystallization in supercritical water is strongly related to the solubility of dissolved species of the zinc ion source, Zn(OH)2 in water. Photoluminescence results showed that the reaction atmosphere determines emission color over a wide range of dominant wavelengths, 534–571nm, according to the crystalline phases formed. The use of pH with supercritical water allows a simple control strategy for emission color control of Zn2SiO4:Mn2+ phosphors.

Synthesis and formation mechanism of Zn 2 SiO 4 nanorods

Zinc silicate (Zn2SiO4) nanorods with diameters of 90–100 nm and lengths of up to 600–700 nm have been successfully prepared by a simple hydrothermal route without the assistance of any templates or surfactants. The characterisations of the products were carried out by X-ray diffraction (XRD), field-emission scanning electron microscopy and transmission electron microscopy technology. On the basis of XRD and scanning electron microscopy analyses of the products at different reaction time periods, an Ostwald ripening mechanism is proposed to elucidate the formation mechanism of the nanorod structure. The electrochemical performance of the as-prepared Zn2SiO4 nanorods was investigated by a galvanostatic charge–discharge method. The results have shown that the Zn2SiO4 nanorods exhibited a higher discharge capacity and better cyclability than the Zn2SiO4 bulk materials.

Fluorescence and thermal stress properties of Yb3+-doped alumino silicate glasses for ultra high peak power laser applications

Various alumino silicate glasses (network modifier ions: Li+, Mg2+, Zn2+ and/or La3+) doped with 1 × 1020 Yb3+ cm−3 (about 0.2 mol% Yb2O3) were prepared. The glasses were studied with respect to their thermo-mechanical and fluorescence properties. Huge differences are found for the coefficients of thermal expansion which determine the thermal shock resistance of the material and hence are required for ultra-high power laser applications. Here, zinc and magnesium alumino silicate glasses show the lowest values. The fluorescence lifetimes of the glasses increase with decreasing average atomic weight of the glass composition (685–1020 µs). All glasses show broad and smooth emission spectra with little variations due to compositional changes.Mixed lithium zinc or lithium magnesium alumino silicate glasses could be promising new laser materials especially with respect to ultra-high peak power systems or applications with high repetition rates.

Influence of thermal annealing and ion irradiation on zinc silicate phases in nanocomposite ZnO–SiOx thin films

The formation of zinc silicate phase in nanocomposite (nc) ZnO–SiOx thin films, its dilution by ion irradiation and subsequent developments were investigated. The nc ZnO–SiOx thin films used in the study were grown using rf magnetron sputter deposition on silicon (Si) substrates. Thin films were also grown on transmission electron microscopy (TEM) grids in identical conditions. The as-deposited films on Si substrates were annealed at 750 and 900°C in air for growth of crystalline zinc silicate phase. The as-deposited and 750°C annealed films were irradiated with 50MeV oxygen ions in the fluence range from 5×1011 to 1×1014 ions cm−2. The presence of zinc silicate was observed by X-ray diffraction (XRD) analysis of the annealed films and by Fourier transform infrared (FT-IR) spectroscopy measurements. XRD and FT-IR analyses of the films show increase in zinc silicate phase with annealing and dilution of zinc silicate phase with irradiation. Photoluminescence (PL) analysis of irradiated as-deposited films show change in defects of ZnO. The results are explained in terms of possible ion irradiation induced modifications in the material.

Characterization of Hydroxyapatite-Glass Composites Using Terahertz Time-Domain Spectroscopy

Terahertz time-domain spectroscopy (THz-TDS) is presented as a tool for characterization of the hydroxyapatite (HA)-glass composites. The materials under investigation are composites of HA and a calcium zinc silicate glass. Our results show that the refractive index and dielectric constant in THz frequencies provide a reliable determination of glass content of these composites. In addition, the THz-TDS is used to morphological changes in HA during simulated body fluid (SBF) incubation. Our results demonstrate that the THz-TDS can be a promising non-destructive tool.

Photoconversion from UV-to-yellow in Mn doped zinc silicate nanophosphor material

A novel synthesis process of Mn doped β-Zn2SiO4 yellow nanophosphors based on sol–gel method is presented. These samples were prepared by a simple solid-phase reaction under natural atmosphere at 1500°C after the incorporation of ZnO:Mn nanoparticles, in silica monolith. XRD showed the formation of zinc silicate β-phase, which shows yellow luminescence. In addition, the as-synthesized β-Zn2SiO4:Mn2+ nanophosphor exhibited intensive broad emission around 574nm, which was attributed to the 4T1–6A1 transition in Mn2+ ions. An exponential fitting analysis has been employed to obtain the lifetime of this yellow emission (574nm), the average lifetime was found to be 13ms. The luminescence properties of our nanophosphors were characterized by excitation and emission spectra as well as luminescence decay.