Structure Of Glass-ceramics Research Articles

Alternatives to Cobalt: Vanadate Glass and Glass-Ceramic Structures as Cathode Materials for Rechargeable Lithium-Ion Batteries

Cobalt-based layered materials have been dominant as cathodes for the rechargeable lithium-ion battery since it was introduced in 1991. Recently, the focus has been on finding novel cathode materials that have significantly higher capacity or voltage than lithium cobalt oxide (practical specific capacity ∼ 140 mA h/g and average voltage ∼ 3.8 V). However, because of the cost and sourcing issues involved with cobalt, which predominately comes from the Democratic Republic of the Congo, looking for less expensive and more abundant alternatives with comparable performance is a growing focus. Here, we report that glass and glass-ceramic vanadate materials showed high initial capacity (>300 mA h/g) and promising cycling stability. Vanadate glass and glass ceramics also showed good rate performance and deeper discharge capability (down to 1.5 V) compared to crystalline counterparts reported in literature. X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy (EDS), and Raman spectroscopy were used to explore the processing-structure–property relationship of vanadate glass and glass-ceramics as novel electrodes. The results indicate that the glass-ceramic-containing β-Li₀.₃₃V₂O₅ crystal has higher initial capacity, but the amorphous glass vanadate shows the most stable cycling performance. Despite the promising performance of glass-based electrodes in which structural stability is not an issue, the continued degradation was still observed. Raman and EDS analyses suggest that vanadate-based cells have the dissolution of vanadium in electrolyte that transports to the lithium metal anode, which is a key issue that must be overcome for these materials to be more stable and commercially applicable.

Низкотемпературный синтез стеклокерамики с кристаллитами YNbO-=SUB=-4-=/SUB=- : Eu-=SUP=-3+-=/SUP=-

The main purpose of this work was to carry out a low-temperature synthesis of glass ceramics containing YNbO4:Eu3+ crystallites and to study the structural and luminescent properties of the obtained samples. Within the framework of this work, the inclusions that crystallized under the conditions of low-temperature synthesis in the systems of SiO2-Na2O-K2O-Y2O3-Nb2O5-Eu2O3 (SiNaK) and B2O5-Na2O-Y2O3-Nb2O5-Eu2O3 (BNa) were investigated for the first time. It was shown that YNbO4: Eu3+ crystallized in both considered systems. In the SiNaK system the crystallization of SiO2 also occurred (quartz, crisstabolite, and tridymite) under the selected conditions. The BNa system proved to be the most promising for the synthesis of activated glass-ceramics with YNbO4, since the required crystallites crystallized only in ithis system. The luminescent properties of crystalline inclusions were investigated using the local cathodoluminescence technique. The composition and structure of glass ceramics were studied by electron-probe microanalysis and X-ray diffraction phase analysis.

Synthesis of 45S5 bioactive glass-ceramic using the sol-gel method, catalyzed by low concentration acetic acid extracted from homemade vinegar

In this paper, two different type of 45S5 bioactive glass-ceramic were compared. Both of them were prepared using the sol-gel method, with two different catalysts: 2 M nitric acid (NACBG) and 10 mM vinegar. Homemade vinegar (HMV) extracted from apples which contained up to 5% acetic acid, as an affordable and low concentration catalyst, was used for the synthesis of 45S5 bioactive glass ceramic called Homemade Vinegar Catalyzed Bioactive Glass (HMVCBG). The substitution of 2 M nitric acid by 87 mM acetic acid strongly reduces the concentration of the acid solution necessary for being a catalyst. The effect of these two catalysts on the structure, morphology, and properties of the bioactive glass-ceramics were investigated. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDXS) and Brunauer–Emmett–Teller (BET) were used to assess surface characteristics and specific surface area, which showed more uniformity and more specific surface area in HMVCBG. Crystallinity and composition were analyzed by X-ray diffraction (XRD), X-ray fluorescence (XRF) and Furrier transform infrared spectroscopy (FTIR) which showed some crystalline phases in BG. In-vitro bioactivity was studied in Phosphate Buffer Saline (PBS) and SEM results showed that HMVCBG has a more uniform hydroxyapatite layer and formation occurs more quickly. This due to the fact that hydroxyapatite is dissolved at a lower rate at higher pH values and it takes longer to form at a higher pH. HMV can form more numerous porosities and a more specific surface area because of higher pH of acetic acid. Hence, PBS solution penetrates to the depth of HMVCBG and hydroxyapatite nucleation form in more spots in the depth of HMVCBG. Thus, HMVCBG has a higher bioactivity level than NACBG.

Barium-Strontium Titanate/Porous Glass Structures for Microwave Applications

Based on porous silicate glasses obtained by ion exchange, glass-ceramic materials containing a solid solution of barium-strontium titanate with a dielectric constant of more than 100 at microwaves, were synthesized for the first time. Glass-ceramic structures were studied using X-ray diffraction, secondary electron microscopy, Mössbauer spectroscopy and porometry methods. Electrical characteristics such as permittivity and losses of as-prepared and annealed in oxygen medium samples were also investigated at microwaves. It was shown that the method of obtaining porous glasses, due to ion exchange between KFeSi glass and LiNO3 and NaNO3 melts, allows for controlling a wide range of pore sizes and makes it possible to form glass porous structures with pores of the required size. The efficiency of the process of filling a porous matrix with a ferroelectric filler was investigated and the average depth of its penetration was estimated. It was shown that annealing glass-ceramic structures in an oxygen environment had a positive effect on their structural and electrical characteristics. Glass-ceramic structures demonstrate a significant increase in permittivity and a decrease in losses after high-temperature treatment in oxygen.

Influence of Fe2+ doping concentration on the structure and spectroscopic properties of transparent glass-ceramics based on Fe2+:ZnAl2O4 nanocrystals

Zinc aluminosilicate glasses nucleated by titanium dioxide, both undoped and doped with 0.6 and 1.0 wt% FeO were prepared by conventional melt-quenching technique and subsequently converted to glass-ceramics by controlled nucleation and crystallization in the temperature range of 720 – 1200 °C. The glasses and glass-ceramics were characterized by X-ray diffraction, Raman and optical spectroscopy. The addition of FeO speeds up the liquid phase separation of the initial glasses and gahnite (ZnAl2O4), rutile (TiO2) and cristobalite (SiO2) crystallization. Ferrous ions enter the gahnite crystals leading to a variation of the absorption spectra of glass-ceramics as compared to those of glasses. The glass-ceramics exhibit a broadband (1.5-2.5 μm) absorption due to the 5E → 5T2 (5D) transition of Fe2+ ions in tetrahedral sites in gahnite nanocrystals. They are promising as materials for gain media and saturable absorbers of mid-infrared lasers.

Effect of Sintering Time on Crystal and Structure of Chlorine-containing Low-titanium Slag Glass-ceramics

Glass-ceramics with akermanite, diopside, spinel and perovskite crystalline phases were prepared by using the direct sintering method and using chlorine-containing low-titanium slag as a raw material. The changes in crystalline phase composition, relative content and microstructure of glass-ceramics sintered at different times were studied. The results suggested crystalline phases remained steady while the relative content of each phase changed significantly. The relative content of akermanite decreased firstly and then increased while those of diopside changed oppositely. The relative content of spinel rose from 6.6% to 9.3% and perovskite stabilized at 10.0-11.1%. In addition, the pore size of glass-ceramics declined firstly and then increased. The optimal microstrure of glass-ceramics were obtained when crystallized at 890 °C for 60 min and sintered at 1185 °C for 60 min. In general, glass-ceramics with compact microstructures could be obtained at appropriate sintering times.

Synthesis, Structure, and Properties of Zirconia-Modified Aluminosilicate Glass-Ceramics

Strontium aluminosilicate glass-ceramics modified with zirconia additions in the presence of yttria as a stabilizing oxide and without it have been prepared by a sol–gel process. Increasing the zirconia content from 5 to 15 wt % has been shown to reduce the gelation time of the starting solutions, lower the gel crystallization onset temperature, activate the glass-ceramic sintering process, and increase the critical stress intensity factor (KIc) of the glass-ceramics by more than a factor of 2. The present results confirm that the increase in KIc on the addition of ZrO2 is due to transformation toughening. At the same time, the addition of yttria as a stabilizing oxide has been shown to hinder the martensitic transformation of tetragonal ZrO2 into the monoclinic phase.

Effect of copper addition on the structure and properties of glass ceramics based on biogenic hydroxyapatite and sodium-borosilicate glass for bone tissue engineering

Effect of copper addition on the structure and properties of glass ceramics based on biogenic hydroxyapatite and sodium-borosilicate glass for bone tissue engineering

Effect of P2O5 and Al2O3 on crystallization, structure, microstructure and properties of Li2O–MgO–Al2O3–SiO2–TiO2–ZrO2 glass ceramics

The structure, microstructure, thermal and mechanical properties of glasses and glass-ceramics in the LMAS (Li2O, MgO, Al2O3, SiO2) system and the effect of P2O5 and Al2O3 additives have been studied. The transition temperatures of both glasses and glass-ceramics increase with the P2O5 and Al2O3 concentration, but at high temperatures the melt viscosity decreases. The main crystalline phases formed are lithium aluminium silicate, enstatite and β-spodumene, being the growth of β-spodumene favoured by fluorine ions, P2O5 and the heat treatment temperature as well. Raman and FT-IR spectroscopies have shown the formation a silica-rich glass phase which acts as a matrix of the crystallites containing Al2O3 and P2O5 in its composition. The shape and aspect ratio of the crystallites depend on the Al2O3 concentration. For low Al2O3 concentration a variety of tubular, granular and plate-like crystals appear, while for high Al2O3 concentration the main shape of the crystals is spherical or globular. Hv, E and CTE properties are related to the crystalline phases formed during the crystallization treatment, and their variations are in accordance with the increase of the crystal aspect ratio. The CTE values of the GCs decrease as the P2O5 content increases up to 3%, while for the Al2O3 concentration of 16% the minimum CTE value is obtained. Hv and E values of the GCs are higher than those corresponding to their respective parent glasses. According to these values, these glasses and glass-ceramics are not appropriate for machining.

Effect of SiO2/Al2O3 ratio on the structure and electrical properties of MgO–Al2O3–SiO2 glass-ceramics doped with TiO2

Glass-ceramics of the MgO–Al2O3–SiO2 (MAS) ternary system were successfully prepared through a melting method with borax, quartz sand, and chemical reagents as the main raw materials. The effects of SiO2/Al2O3 ratios on the structure and properties of glass-ceramics were systematically investigated by differential thermal analysis (DSC), X-ray diffraction (XRD), scanning electron microscope (SEM), dielectric properties and electrical resistivity measurements. The results show that the average coefficient of thermal expansion (CTE) (30–800 °C) of all the samples increased with increasing of the SiO2/Al2O3 ratio, but the density of the glass-ceramics and the grain refinement decreased at the same time. The crystalline phase of all the samples was a prepared sapphirine phase when the SiO2/Al2O3 ratio was equal or greater than 1.78 and a second phase of enstatite precipitation. The electrical performance was the best when the SiO2/Al2O3 ratio was equal to 1.27, and its dielectric constant, dielectric loss, and electrical resistivity (room temperature) were 8.78 (1 MHz), 3.55 × 10−3 (1 MHz), and 10.57 × 10 11 Ω m, respectively.

Effect of high pressure on the structure of barium disilicate glass-ceramics

A systematic study of crystallization of barium disilicate at high pressures and temperatures was undertaken. Two groups of samples were submitted to nucleation at 710°C, and then submitted to a crystal growth at either 860°C or 960°C respectively. Both groups were heat treated at 1 atm, 2.5 GPa, 4 GPa, and 7.7 GPa. The diffraction results show that at atmospheric pressure, the phases formed are, monoclinic Ba6Si10O26, orthorhombic low-Ba2Si4O10, and monoclinic high-Ba2Si4O10 depending on the temperature treatment. In contrast, at 7.7 GPa orthorhombic BaSiO3, monoclinic phase Ba6Si10O26 and coesite formed when treated at 860°C, whereas monoclinic Ba6Si10O26 is predominantly formed when treated at 960°C. At 2.5 and 4 GPa orthorhombic low-Ba2Si4O10 formed when treated at 960°C. The high frequency Raman modes are strongly affected by the different pressure and temperature treatments. The shifts and formations of distinct vibrations modes are discussed as function of pressure.

Preparation and upconversion luminescent properties of Yb3+/Er3+ doped transparent glass-ceramics containing CaF2 nanocrystals

Yb3+/Er3+ doped high-fluoride glass-ceramics were prepared by the high-temperature melting method. The crystal morphology and structure of the rare-earth doped glass-ceramics were characterized by X-ray diffraction, infrared spectra, and high-resolution transmission electron microscope. The influence of crystal size and distribution on the transmittance of glass-ceramics was analyzed. The upconversion emission intensity of the rare earth doped glass-ceramics at different heat treatment temperatures was evaluated. It is shown that the precipitation of CaF2 crystals greatly improves the upconversion emission efficiency of rare earth ions. By analyzing different high-power pump lasers and corresponding up-conversion luminous intensities, the mechanism of up-conversion luminescence of this material is further elaborated.

Li-Ion Conduction Behaviors of Glass-Ceramic Lithium Thiophosphates: Empirical Force Fields and Molecular Dynamics Simulations

The all-solid-state batteries (ASSBs) have drawn increasing interests and demands as the next-generation rechargeable Li-ion batteries (LIBs) for electric vehicles and energy storage devices since they have much more potentials than conventional LIBs [1,2]. However, all we know any further advances in ASSBs are not possible without solving the current raising issues of ASSBs, such as low Li-ion conductivity (σ ion), structural instability, and high resistance of electrode/electrolyte interface [1,2]. Recently, sulfide-based ASSBs are exhibiting the best performance approaching to the commercialization stage with various material advantages (e.g., excellent σ ion, room-temperature formability, and so on) [3,4]. Despite various recent studies on the development of advanced ASSBs, fundamental understanding of fast Li-ion conductors are still lacking. Here, we present an analysis of the Li-ion migration behavior of glass-ceramic (Li2S)0.75(P2S5)0.25 (LPS) structure, a topic that has not yet been investigated, by employing molecular dynamics (MD) simulations.First, we identified unique PS4 3− anion clusters in the short-range region of the glassy structure and newly developed the empirical pair potential (EPP) of the Li-[PS4 3−] bonds. To reasonably represent the ionic and covalent bonds that constitute Li-[PS4 3−] in γ-Li3PS4, EPP was composed of the long-range Coulombic, short-range Morse, and three-body harmonic potentials [5]. The two-body-interaction E I of the Coulombic and Morse potential was expressed as E I = (qiqj / εr) e 2 + D[e -α(r - r0 ) - 2e-2α(r - r0 )], where qi and qj are the ionic charges of the ion i and j, e is the elementary charge, ε is the dielectric constant, r is the distance between the ion i and j, r0 is the equilibrium distance, D is the well-depth, and α is the stiffness parameter, respectively. The three-body harmonic potential E II was expressed as E II = K(θ - θ0)2 , where K is the prefactor and θ0 is the equilibrium angle, respectively. The final converged fitting values are summarized in Table 1, and well reproduce the experimentally observed thermomechanical properties of γ-Li3PS4 [5]. Employing EPP, we constructed the glass−ceramic structure including the crystalline γ-Li3PS4, interfacial, and glassy LPS regions. The density obtained from each part of the glass−ceramic LPS structure agree well with the reported experimental results, and we concluded that our constructed glass−ceramic structure is reasonable. Based on the equilibrated glass-ceramic LPS structure, MD calculation was performed to evaluate the σ ion of each region. The glassy LPS has a σ ion of 4.08 × 10− 1 mS cm− 1, an improvement of ∼100 times relative to that of the γ-phase, which is in agreement with the experiments. By introducing the local S-sublattice analysis, we also found that 40% of the glassy and interfacial region comprised cubic S-sublattice, unlike the crystalline γ-phase, which consisted of only hexagonally closed-packed S-sublattice. These S-sublattice evolutions in the interfacial and glassy domains led to a notable improvement of σ ion.In summary, we determined the EPP of the Li-[PS4 3-] building blocks in (Li2S)0.75(P2S5)0.25 and predicted the σ ion of its glass-ceramic structure. The Li-ion conduction characteristics in the crystalline/interfacial/glassy structure were decomposed by considering the structural ordering differences, The superior σ ion of the glassy structure could be attributed to the fact that ~40% of its structure consists of the short-ranged cubic S-sublattice instead of hexagonally close-packed γ-phase. These results provide new directions for understanding glass−ceramic sulfides with the view of achieving superior Li-ion conducting materials as a solid electrolyte for ASSBs.

Synthesis of SiOC/Al2O3 nano/macro composites through PDC method; investigation of potentials as layers of a packed bed reactor membrane

Thanks to a wide range of pore sizes by nano/macro composites of SiOC/Al2O3, such composites can serve as different layers of the structure of Packed Bed Reactor Membranes (PBRM). In the present study, the Polymer-Derived Ceramics method (PDC) has been used to synthesize nano/macro structures. Firstly, the effect of toluene as an extra carbon source on structure and microstructure of SiOC glass-ceramics was evaluated, such that, 4% (Vol) toluene was recognized as the proper amount to facilitate the synthesis of β-SiC at 1300 °C proved by XRD, Raman spectroscopy, and HR-TEM. Moreover, the presence of micro/meso-porosities was assessed by BET and TEM, indicating the capability of SiOC to serve as the inner part of the membrane. Different amounts of α-Al2O3 altered the distribution of porosities, such that the more the amount of α-Al2O3, the increased the amount of macro-porosities and decreased the amount of micro/meso-porosities. Thus, each composite can act as a layer of membrane to form a gradient structure in pore size distribution.

Crystallization Kinetics and Structural Properties of the 45S5 Bioactive Glass and Glass-Ceramic Fiber Doped with Eu3+

An investigation of the crystallization kinetics of 45S5 Bioglass® using differential scanning calorimetry is presented in this paper. Thermal analysis was performed using the Friedman method. The activation energy and the Avrami index were calculated. The glass samples were subjected to additional controlled heat treatment at 620 °C in order to obtain bioactive glass-ceramics with enhanced mechanical properties. X-ray powder diffraction (XRD) measurements indicated the formation of the glass-ceramic structures of three cyclosilicates: Na4Ca4(Si6O18) or Na6Ca3(Si6O18) or Na16Ca4(Si12O36). Based on middle infrared region (MIR) results, it can be concluded that the crystalline phase present in the tested materials was Na6Ca3(Si6O18) (combeite). Material was doped with Eu3+ ions, which act as a spectroscopic probe for monitoring the structural changes in the glass matrix. The decreasing value of the fluorescence intensity radio parameter indicated symmetry around the europium ions and, thus, the arrangement of the glass structure. The bioactive properties of the examined glass-ceramics were also determined. The bioactive glass fibers doped with Eu3+ were manufactured using two different methods. Its structural and luminescent properties were examined.

Effects of pyrochlore content on the phase, structure, and properties of uranium-rich glass ceramics

In this study, the effects of the pyrochlore content on the phase, structure, and properties of uranium-rich glass ceramics were studied by modifying the mass ratio of the uranium pyrochlore in the glass ceramics. The results indicate that U has a high occupancy rate of approximately 0.7 f.u. at the A position of pyrochlore, and the crystal pyrochlore phase in the glass matrix can increase or decrease according to the U amount in the waste. Specifically, at a high occupancy rate and crystallization amount, the U loads reach 20 wt% in the sample, which exceeds the reported 16 wt% maximal U loads of pyrochlore-based glass ceramics. Furthermore, all the samples have excellent mechanical properties and chemical stabilities. The bulk density of each sample is more than 90% the theoretical density, which is 10–20% higher than those of the glass ceramics prepared by pressure sintering. Moreover, the Vickers hardness values of all samples exceed 6 GPa, and the U leaching rate after 21 days is only 6.7 × 10−5 g m−2 d−1, which is an order of magnitude lower than those of brannerite glass ceramics under equal leaching conditions.

Powder-in-Tube Reactive Molten-Core Fabrication of Glass-Clad BaO-TiO2-SiO2 Glass-Ceramic Fibers.

In this paper we report the fabrication of glass-clad BaO-TiO2-SiO2 (BTS) glass–ceramic fibers by powder-in-tube reactive molten-core drawing and successive isothermal heat treatment. Upon drawing, the inserted raw powder materials in the fused silica tubing melt and react with the fused silica tubing (housing tubing) via dissolution and diffusion interactions. During the drawing process, the fused silica tubing not only serves as a reactive crucible, but also as a fiber cladding layer. The formation of the BTS glass–ceramic structure in the core was verified by micro-Raman spectroscopy after the successive isothermal heat treatment. Second-harmonic generation and blue-white photoluminescence were observed in the fiber using 1064 nm and 266 nm picosecond laser irradiation, respectively. Therefore, the BTS glass–ceramic fiber is a promising candidate for all fiber based second-order nonlinear and photoluminescence applications. Moreover, the powder-in-tube reactive molten core method offers a more efficient and intrinsic contamination-free approach to fabricate glass–ceramic fibers.

Structure, crystallization mechanism, and properties of glass ceramics from molten blast furnace slag with different B2O3/Al2O3

Glass ceramics with different B2O3/Al2O3 from molten blast furnace slag (BF slag) were prepared using traditional melting, annealing, and heat treatment method. According to DSC analysis, the parent glass samples were nucleated at 760 °C for 1 h, and then respectively crystallized at 900 °C, 920 °C, and 940 °C for 1 h. The structure of parent glass was characterized using XRD, Raman spectra, 27Al MAS NMR spectra. The results indicated that with an increasing B2O3/Al2O3, Q2 remained dominant in the glass network, Q0 disappeared and Q4 existed when B2O3/Al2O3 was 0.21. [BO3] and [BO4] were both characterized when B2O3/Al2O3 exceeded 0.09, but the further addition of B2O3 was prior to form [BO3] in glass network. The investigation of crystallization mechanism revealed that the crystallization activation energy Ec strikingly decreased from 403.8 kJ/mol to 277.8 kJ/mol with increasing B2O3, and surface crystallization was determined due to that the crystallization index n was below 3. The results of XRD and SEM-EDS analysis both confirmed the main crystalline in glass ceramics was gehlenite. The flexural strength of glass ceramics reached the minimum when B2O3/Al2O3 was 0.21. Glass ceramics nucleated at 760 °C for 1 h and crystallized at 940 °C for 1 h exhibited the highest flexural strength of 57.61 MPa.

Effects of fluoride content on structure and properties of steel slag glass-ceramics

The hot steel slag were utilized for preparing the glass-ceramics by melting method with different fluoride contents. The crystallization behaviors of the glass-ceramic were characterized by Differential Scanning Calorimeter (DSC), X-ray Diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), Raman, and the Field Emission Scanning Electron Microscope (FESEM).The results established that the transition from Nepheline to Cuspidine, and then to Kalsilite, and finally became Combeite in glass-ceramics occurred with the decrease of fluoride content. Besides, a comprehensive analysis of FTIR and Raman revealed that the addition of fluoride contributed to the formation of the Si–O bridge oxygen in the glass structure, which improved the degree of polymerization of the glass structure and further affected the crystal phase of the glass-ceramics. In addition, when Nepheline and Cuspidine constituted as the major crystalline phases for the prepared glass-ceramics, a higher flexural strength and a smaller volume shrinkage were achieved. SEM depicted that the above mentioned results were ascribed to from the changes in the crystal type and the degree of crystallization, in which the size of the crystal phase had a greater influence on the performance of the glass-ceramic. It was worth noting that the highest flexural strength was 177.76 MPa with the lowest volume shrinkage of 0.06%.

Preparation and Characterization of Glass Ceramics Containing SrTiO3

The glass ceramics containing SrTiO3 crystals were successfully synthesized by high temperature melting crystallization. The optimum technological formula was determined by orthogonal experiment. The heat treatment system of the glass samples were determined by differential scanning calorimeter analysis (DSC). The effects of heat treatment temperature and time on crystal formation and grain size were discussed in detail. The ideal heat treatment condition is at 950°C for 3h. The microstructure and phase structure of glass ceramics were analyzed by scanning electron microscope and X-ray diffraction respectively, which indicate that SrTiO3 crystal were precipitated uniformly in the glass matrix.