Zn2SiO4 Research Articles

Phase equilibria in the NiO-ZnO-SiO2 and PbO-NiO-ZnO-SiO2 systems

Experimental investigation and thermodynamic modeling of the phase equilibria in the (PbO)-NiO-ZnO-SiO2 system has been undertaken to characterize Ni behavior in high-Zn slags. Phase equilibria data at 790–1700 °C were obtained through equilibration of synthetic mixtures in sealed silica ampoules or Pt-Ir / Au foils, rapid quenching, and electron probe X-ray microanalysis. Phase equilibria and liquidus isotherms of the NiO-ZnO-SiO2 system in the tridymite/cristobalite SiO2, monoxide (Ni,Zn)O, zincite (Zn,Ni)O, olivine (Ni,Zn)2SiO4 and willemite (Zn,Ni)2SiO4 phase fields were measured and the extent of the 2-liquid immiscibility gap over cristobalite was determined. Additional solid solutions: larsenite Pb(Zn,Ni)SiO4 and melilite Pb2(Zn,Ni)Si2O7 were measured in the PbO-NiO-ZnO-SiO2 system. It was found that NiO partially substitute ZnO in larsenite and melilite and may form a complete range of solubility in barysilite Pb8(Zn,Ni)Si6O21. New data were used for developing a thermodynamic database to describe the Pb/Cu-containing complex system for characterizing Ni behavior in Zn-containing slags.

Phase equilibria in the ZnO-MgO-SiO2 and PbO-ZnO-MgO-SiO2 systems for characterizing MgO-based refractory – slag interactions

An integrated experimental and thermodynamic modelling investigation of the phase equilibria in the ZnO-MgO-SiO2 and PbO-ZnO-MgO-SiO2 systems in air has been undertaken for characterizing the effect of Zn on MgO-based refractory – slag interactions in the lead processing reactors. New experimental phase equilibria and liquidus data at 725–1740 °C were obtained using high-temperature equilibration of oxide powder mixtures followed by rapid quenching of the samples. Electron probe X-ray microanalysis was used to determine the compositions of the phases present at equilibrium conditions. Wide ranges of solid solutions were identified for periclase (Mg,Zn)O, zincite (Zn,Mg)O, olivine (Mg,Zn)2SiO4, willemite (Zn,Mg)2SiO4, pyroxene (Mg,Zn)SiO3, larsenite Pb(Zn,Mg)SiO4, barysilite Pb8(Zn,Mg)Si6O21 and melilite Pb2(Zn,Mg)Si2O7 phases, indicating possible stabilization of refractories in the presence of ZnO in slag. The experimental results were used for optimization of the parameters in a thermodynamic database that is subsequently used to describe the Pb/Cu-containing multi-component multi-phase system for characterizing slag-refractory interactions.

Zn2 SiO4 Bioceramic Attenuates Cardiac Remodeling after Myocardial Infarction.

In the pursuit of therapeutic strategies for myocardial infarction (MI), a pivotal objective lies in the concurrent restoration of blood perfusion and reduction of cardiomyocyte apoptosis. However, achieving these dual goals simultaneously presents a considerable challenge. In this study, a Zn2 SiO4 bioceramic capable of concurrently sustaining the release of bioactive SiO3 2- and Zn2+ ions, which exhibit a synergistic impact on endothelial cell angiogenesis promotion, cardiomyocyte apoptosis inhibition, and myocardial mitochondrial protection against oxygen-free radical (reactive oxygen species) induced injury is developed. Furthermore, in vivo outcomes from a murine MI model demonstrate that either systemic administration via tail vein injection of Zn2 SiO4 extract or local application through intramyocardial injection of a Zn2 SiO4 composite hydrogel promotes cardiac function and reduces cardiac fibrosis, thus aiding myocardial repair. This research is the first to elucidate the advantageous effects of dual bioactive ions in myocardial protection and may offer a novel therapeutic avenue for ischemic heart disease based on meticulously engineered bioceramics.

Spindle-Like Zinc Silicate Nanoparticles Accelerating Innervated and Vascularized Skin Burn Wound Healing.

The treatment of severe burn injuries is a crucial challenge in skin tissue engineering. Severe burns are always accompanied with large-area neurovascular networks damage, leading to the lack of excitation functions and difficulty in self-healing. Therefore, it is of great importance to develop biomaterials which can not only promote wound healing but also simultaneously reconstruct cutaneous neurovascular networks. In this study, Zn2 SiO4 (ZS) nanoparticles-incorporated bioactive nanofibrous scaffolds are designed for innervated and vascularized skin burn wound healing. ZS nanoparticles with spindle-like morphology are synthesized via a facile hydrothermal method. The incorporation of ZS nanoparticles endows the scaffolds with excellent angiogenic and neurogenic activities in vitro. Additionally, in vivo results show that the ZS nanoparticles-incorporated scaffolds have favorable re-epithelialization, innervation, and vascularization abilities through local release of bioactive Zn and Si ions from ZS nanoparticles, leading to rapid wound healing featuring with newly formed blood vessels and nerve fibers. Taken together, this study suggests that the spindle-like ZS nanoparticles are useful bioactive agents for stimulating vascularization and innervation of functional skin repair. The bioactive inorganic nanoparticles may be used for multifunctional tissue regeneration.

Thermodynamic optimization of the binary CaO–ZnO and ternary CaO–ZnO–SiO2 systems

Liquidus phase equilibrium data of the present authors for the CaO–ZnO–SiO2 system (as a part of research program on the characterization of the multicomponent PbO–ZnO–FeO–Fe2O3-“Cu2O”-CaO-SiO2 system), combined with phase equilibrium and thermodynamic data from the literature, have been used to obtain a self-consistent set of parameters of the thermodynamic models for all phases. The modified quasichemical model is used for the liquid slag phase; lime (Ca,Zn)O, zincite (Zn,Ca)O, α- and α′-dicalcium silicate (Ca,Zn)2SiO4 and tricalcium silicate (Ca,Zn)3SiO5 are described within Bragg-Williams formalism; tridymite, cristobalite SiO2, wollastonite, pseudowollastonite CaSiO3, rankinite Ca3Si2O7, willemite Zn2SiO4, melilite (hardystonite) Ca2ZnSi2O7 and Ca–Zn feldspar CaZnSi3O8 are treated as stoichiometric compounds. From these model parameters, the optimized ternary phase diagram is back calculated.

Experimental Liquidus Study of the Ternary CaO-ZnO-SiO2 System

Phase equilibria of the ternary CaO-ZnO-SiO2 system have been investigated at 1170 °C to 1691 °C for oxide liquid in equilibrium with air and solid oxide phases: tridymite or cristobalite SiO2 (up to two immiscible liquids), pseudowollastonite (CS) CaSiO3, rankinite (C3S2) Ca3Si2O7, dicalcium silicate (C2S) (Ca, Zn)2SiO4, tricalcium silicate (C3S) (Ca, Zn)3SiO5, lime (Ca, Zn)O, zincite (Zn, Ca)O, willemite Zn2SiO4 and hardystonite (melilite) Ca2ZnSi2O7, covering the ranges of concentrations not studied before. High-temperature equilibration on primary phase (silica) or inert metal (platinum) substrates followed by quenching and direct measurement of the Ca, Zn and Si concentrations in the phases with the electron probe X-ray microanalysis (EPMA) has been used to accurately characterize the system. Liquidus phase equilibrium data of the present authors for the CaO-ZnO-SiO2 system are essential to obtain a self-consistent set of parameters of thermodynamic models for all phases.

Composite Nanoscaffolds Modified with Bio-ceramic Nanoparticles (Zn2SiO4) Prompted Osteogenic Differentiation of Human Induced Pluripotent Stem Cells.

Nanofiber scaffolds and bio-ceramic nanoparticles have been widely used in bone tissue engineering. The use of human- induced pluripotent stem cells (hiPSCs) on this scaffold can be considered as a new approach in the differentiation of bone tissue. In the present study, a polyaniline-gelatin-polycaprolactone (PANi-GEL-PCL) composite nanoscaffold was made by electrospinning and modified superficially by plasma method. The synthesized nanoscaffold was then coated with willemite's bio-ceramic nanoparticles (Zn2SiO4). The nanoscaffold's properties were studied by scanning electron microscopy (SEM). Also, nanoparticles characterization was carried out with SEM and dynamic light scattering. The growth and proliferation rate of cells on the synthesized nanoscaffold was examined by MTT assay. Subsequently, hiPSCs were cultured on murine fibroblast cells, incubated in embryoid bodies for 3 days, and placed on the nanoscaffolds. The differentiation potential of hiPSCs was investigated by the examination of common bone markers (e.g. alkaline phosphatase, calcium salt precipitation, and alizarin red test) using bone differentiation factors for 14 days. SEM showed the proper structure of electrospinned nanoscaffolds and coating of nanoparticles on the nanoscaffold surface. The results of MTT assay confirmed the growth and proliferation of cells and the biocompatibility of nanofibers. The results of bone indices also showed that differentiation on the composite nanoscaffold coated with willemite's bio-ceramic nanoparticles dramatically increased in comparison with other groups. Overall, this study demonstrated that PANi-GEL-PCL composite nanoscaffold with willemite's bio-ceramic nanoparticles is a suitable substrate for in vitro growth, proliferation, and differentiation of hiPSCs cells into osteoblasts.

Fabrication and enhanced photoluminescence properties of Sm3+-doped ZnO–Al2O3–B2O3–SiO2 glass derived willemite glass–ceramic nanocomposites

The transparent willemite, Zn2SiO4 (ZS) glass–ceramic nanocomposites were prepared from melt-quench derived ZnO–Al2O3–B2O3–SiO2 (ZABS) precursor glass by an isothermal heat-treatment process. The generation of willemite crystal phase, size and morphology with increase in heat-treatment time was examined by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. The average calculated crystallite size obtained from XRD is found to be in the range 80–120nm. The decreased refractive index with increase in heat-treatment time attributed to partial replacement of ZnO4 units of willemite nanocrystals by AlO4 units and simultaneous generation of vacancies in the Zn-site. Fourier transform infrared (FTIR) reflection spectroscopy exhibits the structural evolution of willemite glass–ceramics. The photoluminescence spectra of Sm3+ ions exhibit emission transitions of 4G5/2→6HJ (J=5/2, 7/2, 9/2, 11/2) and its excitation spectra shows an intense absorption band at 402nm. These spectra reveal that the luminescence performance of the glass–ceramic nanocomposites is enhanced up to 14-fold with crystallization into willemite.

Thermal, Structural, and Enhanced Photoluminescence Properties of Eu3+‐doped Transparent Willemite Glass–Ceramic Nanocomposites

The precursor glass in the ZnO–Al2O3–B2O3–SiO2 (ZABS) system doped with Eu2O3 was prepared by the melt‐quench technique. The transparent willemite, Zn2SiO4 (ZS) glass–ceramic nanocomposites were derived from this precursor glass by a controlled crystallization process. The formation of willemite crystal phase, size, and morphology with increase in heat‐treatment time was examined by X‐ray diffraction (XRD) and field‐emission scanning electron microscopy (FESEM) techniques. The average calculated crystallite size obtained from XRD is found to be in the range 18–70 nm whereas the grain size observed in FESEM is 50–250 nm. The refractive index value is decreased with increase in heat‐treatment time which is caused by the partial replacement of ZnO4 units of ZS nanocrystals by AlO4 units due to generation of vacancies. Fourier transform infrared (FTIR) reflection spectroscopy was used to evaluate its structural evolution. Vickers hardness study indicates marked improvement of hardness in the resultant glass‐ceramics compared with its precursor glass. The photoluminescence spectra of Eu3+ ions exhibit emission transitions of 5D0→7Fj (j = 0, 1, 2, 3, and 4) and its excitation spectra show an intense absorption band at 395 nm. These spectra reveal that the luminescence performance of the glass–ceramic nanocomposites is enhanced up to 17‐fold with the process of heat treatment. This enhancement is caused by partitioning of Eu3+ ions into glassy phase instead of into the willemite crystals with progress of heat treatment. Such luminescent glass–ceramic nanocomposites are expected to find potential applications in solid‐state red lasers, phosphors, and optical display systems.

Improvement of light emission of Mn‐doped Zn2SiO4 phosphors with sodium

Mn-doped willemite (Zn2 SiO4 :Mn) green phosphor were synthesized by sol-gel technology. The effect of the addition of sodium, as in the composition Zn((1.92 - X)) Na(X) Mn(0.08) SiO4, on the emission behavior was studied. FT-IR and EPR results revealed that sodium ion is incorporated into the lattice and results in the formation of isolated Mn2+ and Mn-Mn pairs. The maximum emission intensity of the sample under ultraviolet (UV) excitation occurred at the sodium concentration of x = ~0.03. The green emission at about 525 nm is assigned to Mn2+ -Mn2+ pair centres on nearest neighbour Zn sites. The highest intensity of the green emission for x = ~0.03 is well close to the highest concentration of the Mn2+ -Mn2+ pair.

Exoelectron spectroscopy of traps in surface layers of phenakite and quartz

The possibilities of exoelectron spectroscopy to investigate defects in dielectrics are demonstrated for phenakite Be2SiO4, its structural analogs Zn2 SiO4, Be2GeO4, solid solutions Be2Si1−x Ge x O4 (x=0÷1) and α-quartz. Emission maxima at 330 and 670 K in phenakite have been found to be due to [GeO4]5− andE' centers, respectively. Structural disturbances in the silicon and oxygen positions have been shown to control the exoemission activity of the crystals. Radiation induced decrease of exoemission activity connected with generation ofE' centers by neutron irradiation has been discovered. The energy level scheme of active centers in the subsurface region of Be2SiO4 has been established.