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A list of review papers published in the "Journal of Materials Science" is presented. These include a review of reviews, by Robert W. Cahn, "Glass-ceramics: Their production from wastes--A Review," by R.D. Rawlings, J.P. WU and A.R. Boccaccinig, and "The effect of electric field and pressure on the synthesis and consolidation of materials: A review of the spark plasma sintering method," by Z.A. Munir, U. AnselmiI-Tamburini and M. Ohyanagi.

The influence of tool wear on cutting force in turning glass–ceramics was studied, and a theoretical model of turning force considering tool wear was established in this paper. Firstly, the crack propagation behavior and the form of energy dissipation were analyzed during chip formation, and the model of the force due to chip formation was established based on the fracture mechanics of brittle solids and the principle of energy transfer. Secondly, the mechanical model caused by the flank wear was established by analyzing the microscopic wear mechanism of the tool and the source of friction. Finally, the theoretical model of turning force considering the tool wear was established. The model is only applicable to brittle removal mode. Two different cutting tools were selected to carry out the experiment of turning fluorophlogopite glass–ceramics. The relationship between cutting force and tool wear was discussed, and the accuracy of the model was verified. The results showed that the tool wear has a direct impact on the cutting force, and the theoretical model of cutting force established is in good agreement with the experimental data in this paper. [ABSTRACT FROM AUTHOR]

As a material with both glass and ceramic properties, glass-ceramics have been widely used because of its low expansion coefficient, stable physical and chemical properties, and good mechanical properties. In order to obtain the super-smooth surface of glass-ceramics, the bonnet polishing method was used in this paper. Firstly, the removal mechanism of glass-ceramics was analyzed, and the influence of particle size on the removal mode was obtained by establishing the indentation depth model of free abrasive particles. Secondly, the best polishing slurry formulation was obtained by investigating the dispersion of abrasive particles in polishing slurry with different kinds and contents of dispersants. Then, through the comparative experiment of glass-ceramics polishing, it was proved that the dispersion effect of abrasive particles in polishing slurry has a significant impact on the polishing quality. Finally, through orthogonal experiments, the optimal processing parameters were selected, and only the alumina abrasive particles with an average size of 2.5 μm were used to obtain a super-smooth surface with a surface roughness Ra of 3.16 nm. [ABSTRACT FROM AUTHOR]

Oxyfluoride glass-ceramics (OxGC) present attractive optical properties suitable for many applications. The incorporation of fluoride crystals into silicate matrices improves the luminescence properties, producing materials appropriate for photonic applications. Many papers focus on the preparation of oxyfluoride glass ceramics by melting quenching (MQ), the most widely utilized process. However, in the last decades, the sol-gel process has gained increasing interest as an alternative method for avoiding the MQ drawbacks. The first sol-gel route for producing glass-ceramics with rare earth (RE) doped fluoride nanocrystals were based on the preparation and further mixing of two separate sols. The crystallization of the fluoride nanoparticles occurs during the controlled thermal treatment. More recently, a new sol-gel strategy was proposed, based on the previous synthesis of aqueous fluoride nanoparticles suspensions that are subsequently dispersed in a silica sol-gel matrix. This paper summarizes the most relevant results as well as the advantages and disadvantages of each route and their limitations for future industrial scale up. The synthesis routes are compared considering the structural and morphological characterization, elucidating the crystallization mechanisms, and evaluating the optical properties of the resulting materials. Particular attention is paid to the possibility of producing transparent oxyfluoride glass ceramics films with improved luminescence and enhanced optical properties. [ABSTRACT FROM AUTHOR]

In the present paper, V2O5-TeO2 glass was prepared by the melt-quenching technique. Crystallization of glass with a vanadium content higher than 35%mol results in an increase in electrical conductivity by a few orders of magnitude and a decrease in activation energy from ~0.40 to ~0.12 eV. In this work, a critical review of existing charge transfer models was presented on the example of V2O5-TeO2 glass and glass–ceramics. Schnakenberg's and Friedman-Triberis' charge transfer models were found to be applicable to both glass and glass–ceramics. Optical phonon frequencies obtained from Schnakenberg's model are in agreement with FTIR studies. Values of activation energies obtained from the Schnakenberg model decrease after crystallization. Friedman-Triberis' model shows an increase in the density of states near the Fermi level from 1019 eV−1 cm−3 in glass, to 1021 eV−1 cm−3 in glass ceramics. Structural studies show that the main crystallizing phase is Te2V2O9 which occurs with the V2O5 shell in glasses with compositions 50–50%mol and 45–55%mol. It is concluded that crystallization results in the reduction of vanadium ions in the remaining glass matrix which leads to an increase in the V4+/V5+ ratio and therefore, an increase in electrical conductivity. [ABSTRACT FROM AUTHOR]

The widespread use of flat electric heaters in equipment and household appliances requires the search for simpler and cheaper technologies for their production. This paper proposes a method for producing an electrically conductive coating (NiAl) and an electrically insulating layer (glass ceramics) in one stage: self-propagating high-temperature synthesis in a thermally coupled (Ni + Al)/(PbO2 + B + Al2O3 + glass) powder mixture. The combustion wave front propagation process is investigated, and the effect of layer thickness along with the ratio of the PbO2 + B + Al2O3 + glass powder mixture components on the wave front propagation velocity and the wave front temperature is described. It is revealed that the wave front of the exothermic process expands when a PbO2 + B mixture is added to the bottom layer. The addition of this mixture makes it possible to reduce the NiAl layer thickness and ensure the formation of a uniform dielectric coating. The phase composition and microstructure of the coating are studied. Optimal ratios are determined for layer thicknesses and the composition of the powder mixture of the layers. The fundamental possibility of forming an electrically conductive and dielectric coating by the method of self-propagating high-temperature synthesis in one stage is shown. [ABSTRACT FROM AUTHOR]

In this paper, gamma radiation shielding properties of same glass ceramics are reported for 356, 662, 1173, and 1330 keV gamma energies. Firstly, the validity of the FLUKA method was determined using the (90–x)TeO2-xMoO3-10ZnO glass system whose shielding parameters were determined by different analytical methods in the literature. The mass attenuation coefficients (µm), half-value layer, and mean free path parameters for the glass ceramic samples were calculated by the FLUKA. When the results obtained with the FLUKA and XCOM database were examined, it was found that glass f6, which is one of the PbO–Al2O3–SiO2–TiO2 glass-ceramic samples, had the highest gamma shielding property among the glass ceramics. Additionally, comparisons show that the FLUKA code is an alternative method to analytical methods for determining gamma shielding parameters and it is a tool that can provide preliminary information and comparisons for experimental studies. [ABSTRACT FROM AUTHOR]

Antimicrobial potential of bioactive glass (BAG) makes it promising for implant applications, specifically overcoming the toxicity concerns associated with traditional antibacterial nanoparticles. The 58S composition of BAG (with high Ca and absence of Na) has been known to exhibit excellent bioactivity and antibacterial behaviour, but the mechanisms behind have not been investigated in detail. In this pioneering study, we are using Atomic Force Microscopy (AFM) to gain insights into 58S BAG's adhesive interactions with planktonic cells of both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria; along with the impact of crystallinity on antibacterial properties. We have recorded greater bacterial inhibition by amorphous BAG compared to semi-crystalline glass–ceramics and stronger effect against gram-negative bacteria via conventional long-term antibacterial tests. AFM force distance curves has illustrated substantial bonding between bacteria and BAG within the initial one second (observed at a gap of 250 ms) of contact, with multiple binding events. Further, stronger adhesion of BAG with E.coli (~ 6 nN) compared to S. aureus (~ 3 nN) has been found which can be attributed to more adhesive nano-domains (size effect) distributed uniformly on E.coli surface. This study has revealed direct evidence of impact of contact time and 58S BAG's crystalline phase on bacterial adhesion and antimicrobial behaviour. Current study has successfully demonstrated the mode and mechanisms of initial bacterial adhesion with 58S BAG. The outcome can pave the way towards improving the designing of implant surfaces for a range of biomedical applications. [ABSTRACT FROM AUTHOR]

Production of high-grade graphene-like materials using a simple, reliable processes and its simultaneous transfer onto soft surfaces have not yet achieved; hence impeding wide-ranging graphene applications. Even more complex processes are required to prepare graphene-based nanohybrids, which offer additional synergistic functionalities in relation to graphene. Here, an uncomplicated and scalable process to prepare high-purity few-layer turbostratic graphene and graphene/SiOx nanohybrids is demonstrated employing laser-mediated explosive synthesis and transfer of graphene flakes. The process is capable of producing, and simultaneously transferring, graphene flakes on any substrate, such as polymer, glass, metal, ceramics, etc. Graphene and nanohybrids exhibit sp2 structures of turbostratic stacking, with low sheet resistance and very high (~30) C/O ratio. The merits of the method are showcased by two energy-related examples, flexible single-electrode triboelectric nanogenerators and electric double-layer capacitors. This method emerges as a paradigm of additive manufacturing for graphene-based devices with impact for applications in flexible electronics. [ABSTRACT FROM AUTHOR]

This paper presents a method for the fabrication of a foam glass ceramic, an inorganic heat-insulating material, by extruding a mixture of opal–cristobalite rock and a sodium hydroxide solution through calibrated holes. The method ensures excellent mixture homogenization and allows mixing of components and granulation of the mixture to be combined in a single step. As a result of active reactions of amorphous phases in the opal–cristobalite rock with sodium hydroxide in the SiO2–Na2O–H2O system, the average density of the material decreases by a factor of 1.5. This ensures an economic benefit: a proportional reduction in the percentage of sodium hydroxide, an expensive component. Using electron microscopy, we have assessed the effect of temperature on structure formation in the material. The pore formation process begins at 200°C and is accompanied, up to 500°C, by the formation of a loose structure in the form of an inhomogeneous network. In the range 400–500°C, the material undergoes a transition. Above 600°C, a cellular structure begins to form. As a result, the materials synthesized at 850°C have an average density from 0.38 to 0.57 g/cm3 and compressive strength from 3.1 to 5.9 MPa. [ABSTRACT FROM AUTHOR]

This paper presents a method of calculating and estimating the composition of starting mixtures for metasilicate glass-ceramics of a new class: Sikams. The method relies on crystal-chemical principles and takes into account isovalent and heterovalent isomorphism under directional solidification conditions. It ensures a high crystallization rate, a desired degree of structural and chemical homogeneity, and optimal physicochemical properties of the material, in which the crystalline component consists of pyroxene solid solutions. Moreover, it simplifies the fabrication process and reduces energy consumption. [ABSTRACT FROM AUTHOR]

Subsurface damage and edge chipping remain a persistent technical challenge for the abrasive machining of dental restorations made from glass ceramics, and they impede the fabrication of long-lasting dental restorations. This paper reports on an integration of ultrasonic assistance to dental high-speed rotary abrasive machining for improvement of the surface quality of glass ceramics. An ultrasonic assisted computer-controlled high-speed rotary cutting apparatus was designed and fabricated with functions of ultrasonic vibration, automatic cutting, and force measurement. A multi-phase feldspar glass ceramic with the highest brittleness among glass ceramics was selected for the study. Machining forces, surface roughnesses, and edge chipping damage were evaluated for a range of cutting conditions with and without ultrasonic vibrations. Our most significant finding is that ultrasonic assisted machining led to a clear and consistent reduction of edge chipping and thus subsurface damage. Ultrasonic machining also achieved significant reductions in normal and tangential forces, and surface roughness at higher removal rates (p < 0.05). Our results suggest that ultrasonic assisted dental machining may be a way to improve quality and lifetime of ceramic dental restorations, whose failures are rooted in chipping damage and surface flaws using current machining techniques. [ABSTRACT FROM AUTHOR]

A glass with the nominal composition of 28Y48Si24Al83O17N (in equal percentage) was chosen as parent glass in this paper to prepare YAlO-based glass-ceramics. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to assess the crystallization process of the parent glass. YAG as the only crystalline phase appears in all glass-ceramics produced under 1250°C. A small amount of O'-Sialon secondary phase starts to precipitate from parent glass samples as heat treatment temperature increases to 1250°C. Grain size of the dendrite crystal which corresponds to YAG phase increases and the dendrite branches get thickened as heat treatment temperature increases. Moreover, grain size of YAG phase resulting from two-stage heat treatment is much smaller than that of YAG phase obtained by one-stage heat treatment. The results are relevant to developing improved crystallization treatments for glasses with potential for crystallization to YAG-based glass-ceramics and for heat treatments of YAG/ β-SiAlON materials. [ABSTRACT FROM AUTHOR]

In this paper, the composites of the TiO-CaO-MgO-AlO-SiO glass-ceramic were successfully produced by the method of Sol-Gel from tetrabutyl titanate as the titanium (Ti) source, which were sintering at 1300 °C for 2 h. The dielectric properties of the composites were studied. The highest energy density reached 1.05 J/cm with low loss (<0.01), ε = 109 and the breakdown voltage of 48.29 kV/mm, which was 1.38 times higher than that of pure TiO(0.76 J/cm). [ABSTRACT FROM AUTHOR]

Optical fiber with YPO4:Pr3+ nanocrystals (NCs) is presented for the first time using the glass powder—NCs doping method. The method's advantage is separate preparation of NCs and glass to preserve luminescent and optical properties of NCs once they are incorporated into optical fiber. The YPO4:Pr3+ nanocrystals were synthesized by the co-precipitation and hydrothermal methods, optimized for size (< 100 nm), shape, Pr3+ ions concentration (0.2 mol%), and emission lifetime. The core glass was selected from the non-silica P2O5-containing system with refractive index (n = 1.788) close to the NCs (no = 1.657, ne = 1.838). Optical fiber was drawn by modified powder-in-tube method after pre-sintering of glass powder—YPO4:Pr3+ (wt 3%) mixture to form optical fiber preform. Luminescent properties of YPO4:Pr3+ and optical fiber showed their excellent agreement, including sharp Pr3+ emission at 600 nm (1D2–3H4) and 1D2 level lifetime (τ = 156 ± 5 µs) under 488 nm excitation. The distribution of the YPO4:Pr3+ NCs in optical fiber were analyzed by TEM-EDS in the core region (FIB-SEM-prepared). The successful usage of glass powder—NCs doping method was discussed in the aspect of promising properties of the first YPO4:Pr3+ doped optical fiber as a new way to develop active materials for lasing applications, among others. [ABSTRACT FROM AUTHOR]

Crystallisation of bioactive glasses has been claimed to negatively affect the ion release from bioactive glasses. Here, we compare ion release and mineralisation in Tris–HCl buffer solution for a series of glass–ceramics and their parent glasses in the system SiO2–CaO–P2O5–CaF2. Time-resolved X-ray diffraction analysis of glass–ceramic degradation, including quantification of crystal fractions by full pattern refinement, show that the glass–ceramics precipitated apatite faster than the corresponding glasses, in agreement with faster ion release from the glass–ceramics. Imaging by transmission electron microscopy and X-ray nano-computed tomography suggest that this accelerated degradation may be caused by the presence of nano-sized channels along the internal crystal/glassy matrix interfaces. In addition, the presence of crystalline fluorapatite in the glass–ceramics facilitated apatite nucleation and crystallisation during immersion. These results suggest that the popular view of bioactive glass crystallisation being a disadvantage for degradation, apatite formation and, subsequently, bioactivity may depend on the actual system study and, thus, has to be reconsidered. [ABSTRACT FROM AUTHOR]

This paper presents a physicochemical study of NaMgSc(MoO) (0 ≤ x ≤ 0.5) glassceramics and oxide glasses containing different amounts of bismuth oxide and having broad glass-forming regions, which allows the composition and properties of the materials to be varied over a rather wide range. We have studied Eu luminescence under ultraviolet excitation in glass-ceramics containing a crystalline phase with the composition NaMgSc(MoO):Eu (0 ≤ x ≤ 0.5). The highest Eu luminescence intensity is offered by the NaMgSc(MoO) and NaMgSc(MoO) materials. With increasing EuO concentration, the luminescence intensity increases, reaching the highest level at 5 mol %. The glass-ceramics have trigonal symmetry (sp. gr. $$R\bar 3c$$). The emission band at 614 nm (Eu D → F transition) has high intensity, whereas the bands at 592 and 596 nm ( D → F transition) are rather weak. This suggests that NaMgSc(MoO):Eu (0 ≤ x ≤ 0.5) glass-ceramics are potentially attractive, bright red phosphors. [ABSTRACT FROM AUTHOR]

This article presents the results from a traverse internal cylindrical grinding process conducted using grinding wheels with sol-gel alumina abrasive grains and varying volumes of glass-ceramic vitrified bond. The aim was to determine how changing the bond volume within the range of V = 11.5-14.5 % influenced the wear phenomenon of the microcrystalline sintered corundum abrasive grains and the ceramic bond bridges with glass-crystalline structure. The paper presents grinding wheels with conic chamfer and the most important wear phenomena of the grinding wheel components occurring in the area of contact between the tool and the workpiece material. The work includes the methodology of the experimental tests on the traverse internal cylindrical grinding of bearing rings made from steel 100Cr6 (62 ± 2 HRC). A wide range of test results were analyzed, including machined surface roughness parameters ( Ra, Rz, Sm, Δa), grinding power, grinding wheel volumetric wear V, material removal V, G-ratio, root-mean-square roundness deviation from mean circle ( Δ, rms), grinding wheel edge wear, grinding wheel microtopography parameters ( Sa, St, Sdr, Sds), and SEM images of the wear marks on the grinding wheel active surface. The dominant wear phenomena of the grinding wheels with conic chamfer and the influence of the bond volume share on its intensity were experimentally determined. The results show that the decrease in bond volume from V = 14.5 to 11.5 % increases the grinding wheel life by twofold. This was due to a decrease in abrasive wear and plastic flow phenomena and to a greater fracture wear (mostly fatigue and thermal-fatigue). These events led to a periodic shedding of the oxide layer and the plastically deformed grain layer and also revealed the crystals' sharp edges, located below the plastically deformed surface layer. [ABSTRACT FROM AUTHOR]

This paper reports on damage morphology created in low-cycle high-load spherical indentations of feldspar porcelain and leucite glass ceramic to mimic teeth clenching or grinding. Maximum contact stresses were evaluated as functions of cycle numbers and applied loads using a Hertz model. The surface damage of the two materials after low-cycle high-load indentation testing was viewed using scanning electron microscopy to understand the relations between crack propagation and microstructures. The results indicate that the maximum contact stresses for both materials reduced significantly with the cycles (ANOVA, p < 0.05) but did not show a significant change with the applied loads (ANOVA, p > 0.05). Feldspar porcelain can endure much less maximum contact stress than leucite glass ceramic. Low-cycle high-load spherical indentations induced extensive ring cracks, wedging of crack faces by debris, fragmentation, and pulverization on feldspar porcelain surfaces. In contrast, leucite glass ceramic surfaces yielded only minimum microcracks at 500 N load and localized fractures and cracks at the higher loads of 600 and 700 N. This study shows that leucite glass ceramic had much higher resistance to low-cycle high-load fatigue impacts than feldspar porcelain and it can be a better choice for restorations under teeth clenching and grinding conditions. [ABSTRACT FROM AUTHOR]

This paper is the first report on high strength glass-ceramics which mainly contain zirconia as crystalline phase. This is in contrast to previous reports on high strength glass-ceramics which contain low quartz as the crystalline phase. Glasses in the system MgO/Y2O3/Al2O3/SiO2 with zirconia as nucleating agent were melted. The samples were crystallised in a first step at 950 °C for different periods of time and in the second step at 1060 °C for 1 h. The prepared glasses and glass-ceramics were characterised using differential thermal analysis, dilatometry, X-ray diffraction, and scanning electron microscopy. As shown by X-ray diffraction after the first step in every analysed composition, zirconia was precipitated. With increasing crystallisation time and temperature and depending on the composition, the other phases such as β- or α-quartz solid solutions, spinel and indialite were precipitated. With higher yttria concentrations and increasing crystallisation temperatures during the second crystallisation step, the main crystalline phase was zirconia whereas the quartz solid solution was no longer observed. Bending strengths up to 450 MPa and Young′s moduli up to 115 GPa were obtained after the two subsequent crystallisation steps. Higher yttria concentrations resulted in an increase in density and microhardness. The maximum Vickers hardness was 10.5 GPa. [ABSTRACT FROM AUTHOR]

One of the biggest challenge in the microfluidic channel fabrication in glass-ceramics or so called low temperature co-fired ceramics (LTCC) is the elimination of channel deformation during lamination. In this paper the expected deformation of the substrate and the sacrificial layer (starch powder and 3D printed UV polymerized material) during the lamination process of microfluidic structure fabrication is described. The choice of sacrificial volume material (SVM) plays an important role in channel deformation. Two types of SVM were investigated considering the width of the channel and the applicability. Uniaxial compression and Jenike shear test was used to obtain the mechanical parameters of starch SVM. To determine the stress-strain characteristics of LTCC uniaxial compression experiment was conducted. The shape of the laminated LTCC containing embedded channel was modeled by finite element method using the mechanical parameters obtained by the measurements. A design rule is given considering the channel width and the choice of SVM based on the simulation results. [ABSTRACT FROM AUTHOR]

The conversion of 45S5 glass and glass-ceramics to a hydroxyapatite (HA)-like material in vitro has been studied extensively, but only for short reaction times (typically <3 months). In this paper, we report for the first time on the long-term conversion of 45S5 glass-ceramic microspheres (designated 45S5c) in an aqueous phosphate solution. Microspheres of 45S5c (75-150 μm) were immersed for 10 years at room temperature (~25 °C) in KHPO solution with a concentration of 0.01 M or 1.0 M, and with a starting pH of 7.0 or 9.5. The reacted 45S5c microspheres and solutions were analyzed using structural and analytical techniques. Only 25-45 vol% of the 45S5c microspheres were converted to an HA-like material after the 10 year reaction. In solutions with a starting pH of 9.5, an increase in the KHPO concentration from 0.01 to 1.0 M resulted in a doubling of the volume of the microspheres converted to an HA-like material but had little effect on the composition of the HA-like product. In comparison, reaction of the 45S5c microspheres in the solution with a starting pH of 7.0 resulted in an HA-like product in the 0.01 M KHPO solution but a calcium pyrophosphate product, CaK(PO).9HO, in the 1.0 M solution. The consequences of these results for the long-term use of 45S5 glass-ceramics in biomedical applications are discussed. [ABSTRACT FROM AUTHOR]

In this paper, particle sintering technology was used to transform tantalum niobium tailings (Nb-Ta tailings) into glass ceramic products. CaO, ZnO and BaO were used to adjust the composition of the glass. β-wollastonite was found as the major crystalline phase in all treated samples. With the CaO increasing, the intensity of crystal diffractive peaks is also increasing. The formation of β-wollastonite crystal can be accelerated by the increasing of CaO. The sintering is processed under the participation of liquid phase, and the increase of sintering temperature does a great favor on descending the liquid phase viscosity of glass particles, which consequently is available for sintering. The density and sintering quality of the samples prepared by two-step sintering are higher than that of one-step sintering. As the sintering temperature increases, the surfaces of the samples become better and have beautiful luster. [ABSTRACT FROM AUTHOR]

Recently, several methods have been reported for fabricating tailored amorphous multi porosity bioscaffolds for bone regeneration and tissue engineering. In particular, the melt-quench-heat-etch method appears attractive for making large and/or complex shape structures or fibers for flexible products. However, often the macropore size has been limited to <100 μm. In this paper we report an improved method for fabricating nano-macroporous soda lime phosphosilicate glass using sucrose as a macropore former. The composite compact consisting of soda lime phosphosilicate glass and sucrose powders is pressed in a die at room temperature. 3D interconnected macroporous structure is formed first by dissolving the sucrose part in water at room temperature, and then sintering the compact at temperatures above the glass transition temperature. Thus, interconnected macropores with controlled size (≥100 microns) are formed readily. The sintering heat-treatment also induces nanoscale phase separation, which is then exploited for introducing nanoscale porosity. For the latter goal, the sample is leached in HCl under optimized conditions to yield desired nano-macroporous glass for bone scaffold or other applications. [ABSTRACT FROM AUTHOR]

In this paper, we describe the fabrication of Li2O-Al2O3-SiO2 (LAS) crystallized preforms with suitable drawing formability, and the characteristics of drawn LAS glass-ceramic capillaries. It was found that addition of K2O to the LAS glasses reduces crystallinity of the crystallized preforms and forms low-viscosity glass matrices. It was confirmed that, by using a parallel plate viscometer, such crystallized preforms show suitable viscosity for drawing below the melting temperatures of the crystalline phase. We also proved that the addition of K2O is effective in stabilizing the preforms by preferential precipitation of stable β-spodumene solid solution (s.s.), which is essential in preventing the deposition of coarse surface crystals during the drawing. The LAS glass-ceramic capillaries drawn from the crystallized preform containing 50 mass% β-spodumene s.s. showed a dimensional accuracy within sub-micrometers. It was confirmed that the glass-ceramic capillaries have a low thermal expansion coefficient (25 × 10-7/K) and excellent mechanical and chemical durability, making them promising candidate components of fiber-optic devices. [ABSTRACT FROM AUTHOR]

The La2O3–B2O3–SrO glass ceramics containing LaBO3 were prepared by melt crystallization method and doped with Tb3+/Eu3+ for luminescence performance investigation. The heat treatment conditions of the glass ceramics were determined by differential thermal analysis (DTA), X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The crystallization kinetics parameters such as crystallization activation energy Ec, Avrami index n were calculated by thermal analysis. Emission peaks at 489, 544 nm of Tb3+ and 590, 614 nm of Eu3+ were obtained under excitation at 377 nm. The tunable warm white light emission was obtained by varying the concentration of Eu3+ in Tb3+/Eu3+ co-doped glass ceramics. The temperature-dependent luminescence spectra show that at 150 °C the intensity of the emission peak can still reach more than 85% of the room temperature. Tb3+/Eu3+ co-doped La2O3–B2O3–SrO glass ceramics have high thermal stability and high luminescence properties, which can be applied to white LEDs and display devices. [ABSTRACT FROM AUTHOR]

Si3N4 is a promising material for heat dissipation substrate due to its excellent thermal conductivity and mechanical properties. However, its application is limited by the difficulties in surface metallization. In this work, surface metallization of Si3N4 ceramic substrate is realized by thick film method for the first time. Conductive silver paste containing Bi2O3-B2O3-ZnO glass frit as glass binder was prepared, and high-performance silver thick films were formed on Si3N4 ceramic surface. The mechanical and electrical properties of silver films were significantly promoted with increasing sintering temperature, and silver films with high shear strength of 23.35 MPa and low resistivity of 3.41 μΩ·cm were obtained when sintered at 600 °C. In the meanwhile, the silver films exist high reliability under thermal cycles. The bonding between the silver thick film and Si3N4 ceramic substrate was considerably enhanced as a result of interfacial reaction, forming Bi2Si2O5 phase at the interface during sintering process. The formation mechanism was discussed and it is of great significance for the interfacial design in future studies. The results suggest that thick film method is a promising technology for obtaining high-quality surface metallization for Si3N4 ceramic substrate. [ABSTRACT FROM AUTHOR]

The results of an investigation of the influence of the chemical composition, material structure, crystallization features, and isomorphic substitutions in pyroxene solid solutions of the augite type on the mechanical characteristics of glass ceramics are presented. The mechanism of structure formation is demonstrated, which consists in the crystallization of chromium spinel and subsequent growth on its surface of crystals of a pyroxene solid solution of the augite type in the form of spherical intergrowths, which effects high mechanical strength of glass-ceramic proppants. It was found that on isomorphic substitutions occurring in the diopside-augite series the mechanical strength of glass-ceramic proppants increases, which is correlated with a reduction of bond lengths and an increase in their number as well as compaction of the unit cell. [ABSTRACT FROM AUTHOR]

Easy-to-manufacture Li2S-P2S5 glass ceramics are the key to large-scale all-solid-state lithium batteries from an industrial point of view, while their commercialization is greatly hampered by the low room temperature Li+ conductivity, especially due to the lack of solutions. Herein, we propose a nanocrystallization strategy to fabricate super Li+-conductive glass ceramics. Through regulating the nucleation energy, the crystallites within glass ceramics can self-organize into hetero-nanodomains during the solid-state reaction. Cryogenic transmission electron microscope and electron holography directly demonstrate the numerous closely spaced grain boundaries with enriched charge carriers, which actuate superior Li+-conduction as confirmed by variable-temperature solid-state nuclear magnetic resonance. Glass ceramics with a record Li+ conductivity of 13.2 mS cm−1 are prepared. The high Li+ conductivity ensures stable operation of a 220 μm thick LiNi0.6Mn0.2Co0.2O2 composite cathode (8 mAh cm−2), with which the all-solid-state lithium battery reaches a high energy density of 420 Wh kg−1 by cell mass and 834 Wh L−1 by cell volume at room temperature. These findings bring about powerful new degrees of freedom for engineering super ionic conductors. The development of Li2S-P2S5 glass ceramics is greatly hampered by the low room temperature lithium conductivity. Here, the authors propose a nanocrystallization strategy to fabricate super lithium conductive glass ceramics. [ABSTRACT FROM AUTHOR]

Polymer-derived SiBCN ceramics are well known for their outstanding thermal stability. Although they possess outstanding thermal stability, SiBCN ceramics are easily to decompose out Si3N4 and SiC crystalline phases at high temperature leading to thermal stability worsen. Here, to reduce the Si3N4 crystallization precipitation in SiBCN ceramics, the N contents are reduced from 25 to 8.09 wt%, 11.44 and 14.51 wt%, by adding polycarbosilane into polyborosilazane, respectively. The experimental results illustrated that the precipitation temperature of Si3N4 phase in modified S1–S3 ceramics increased to 1800 °C which was higher than that of S0 ceramics (1600 °C). The results indicated that the crystalline precipitation of Si3N4 in SiBCN ceramics can be suppressed at a high-temperature environment via declining N content, which may provide a new strategy for decreasing carbothermal reduction. In addition, the original SiBCN ceramic had a weight change of 31.7% at T > 1800 °C, while the weight change of modified SiBCN ceramics significantly reduced to 15.7 ~ 19.5%, which attributed to the decrease in carbothermal reduction. [ABSTRACT FROM AUTHOR]

Ion exchange is a chemical method to increase the mechanical strength on the surface of glass-based materials, in which an exchange between an alkaline ion with smaller radius (from glass) and an alkaline ion with larger radius (from molten salt) is promoted. This creates a superficial compression layer, resulting in mechanical strengthening, compensating the cracks created during processing and use of those glass-based materials. In this context, lithium-based sintered glass-ceramics belonging to the Li2O-ZrO2-SiO2 (LZS) and Li2O-ZrO2-SiO2-Al2O3 (LZSA) systems were summited to ion exchange in a NaNO3 salt bath. The temperatures used in these processes varied from 430°C to 500°C, with immersion times from 15 min to 3 h. After the thermal chemical processes, the LZS glass-ceramics presented a sodium content from 0.20 wt.% to 3.11 wt.%, layer depth up to 2500 µm, and mechanical strength increase up to 19.6%. For the LZSA glass-ceramics, the sodium content varied from 0.23 wt.% to 1.03 wt.% and a layer depth up to 2300 µm was obtained, with a 30.4% mechanical strength decrease. For both glass-ceramics systems, a diffusion coefficient in the order of 10−5 cm2/s and a Weibull modulus increase were demonstrated. For comparison, the results of previous research work, in which ion exchange using a NaNO3 salt paste method, are also related. [ABSTRACT FROM AUTHOR]

The co-firing compatibility between green tape and the Ag electrode is a crucial characteristic in low-temperature co-fired ceramic (LTCC) technology and plays a vital role in improving the performance and application status of LTCC device modules. In this work, we studied the effects of lead content on the glass viscosity, the microstructure, and co-firing compatibility of silver electrode film. It was found that the softening point and viscosity of the glass were decreased, and the wettability between the glass and silver was improved with the increase of the lead content, which promoted the co-firing densification and interfacial bonding between the silver electrode film and the ceramic layer. The film presented the best electrical properties co-firing at 875 °C for 15 min, with the resistivity of 1.21 mΩ/sq. And the film was densified. The sintering interface was clear and well bonded. The results showed that an appropriate lead content in glass could effectively improve the interfacial bonding and the electrical properties during co-fired process, providing a new control methodology for realizing co-fired matching of the silver electrode film with low-temperature co-fired ceramics. [ABSTRACT FROM AUTHOR]

Elevated serum urate (hyperuricemia) promotes crystalline monosodium urate tissue deposits and gout, with associated inflammation and increased mortality. To identify modifiers of uric acid pathologies, we performed a fly Genome-Wide Association Study (GWAS) on purine metabolites using the Drosophila Genetic Reference Panel strains. We tested the candidate genes using the Drosophila melanogaster model of hyperuricemia and uric acid crystallization ("concretion formation") in the kidney-like Malpighian tubule. Medusa (mda) activity increased urate levels and inflammatory response programming. Conversely, whole-body mda knockdown decreased purine synthesis precursor phosphoribosyl pyrophosphate, uric acid, and guanosine levels; limited formation of aggregated uric acid concretions; and was sufficient to rescue lifespan reduction in the fly hyperuricemia and gout model. Levels of mda homolog FAM214A were elevated in inflammatory M1- and reduced in anti-inflammatory M2-differentiated mouse bone marrow macrophages, and influenced intracellular uric acid levels in human HepG2 transformed hepatocytes. In conclusion, mda/FAM214A acts in a conserved manner to regulate purine metabolism, promotes disease driven by hyperuricemia and associated tissue inflammation, and provides a potential novel target for uric acid–driven pathologies. [ABSTRACT FROM AUTHOR]

LiFe1−xEuxPO4 (x = 0–0.1) samples were successfully fabricated by glass–ceramics technique quenching from high temperature. Thermal properties were analyzed by DTA analysis. Crystallization activation energy and Avrami parameters were calculated depending on the Eu content and heating rates. The XRD analysis shows that there are two-phases of LiFePO4 and Li3Fe2P3O12 which compete with Eu-doping in the samples and it is found that the x = 0.02 sample has the lowest impurity phases. The battery cells exhibit similar cycling voltammetry (CV) data with the undoped LiFePO4 battery cells. The charging/discharging cycles measurements were done for C/2-rate at room conditions and the best capacity value for C/2-rate was obtained as 149.4 mAh/g for x = 0.02 Eu-doped sample. Although the best capacity was obtained for x = 0.02, the best capacity fade was obtained for x = 0.03 Eu-doped sample. C-rate measurements provided that x = 0.02 cells have the promising results for the battery applications. [ABSTRACT FROM AUTHOR]

Due to an easy sintering stage, composite aerogels offer an alternative way to synthesize silica glass at temperatures ranging from 900 to 1200 °C, close to half the temperatures used for the glass melting process. The heat treatment is tailored to obtain fully densified or porous glasses. In this study, the kinetics of dimensional shrinkage were characterized during the sintering mechanism, and we confirmed that the viscous flow-sintering model also applies to composite aerogels. Porous glasses with a broad range of porosity and physical properties (mechanical strength, elasticity modulus, permeability) have been synthesized. The synthesis of glass-ceramics from these open pore structures is explored. Highlights: Synthesis of porous glasses with porosity 95–0 percent from composite aerogels. The addition of aerosil (silica powder) in the sol gel solution tailors the composite aerogels physical properties. The composite aerogels sintering is a viscous flow process described by the Scherer's model. The mechanical properties and the permeability of the porous glasses evolves over 3 and 4 orders of magnitude, over the whole porosity range. [ABSTRACT FROM AUTHOR]

New ceramic composites were developed employing hazardous car production sludge (CPS) and galvanic process glass waste with high heavy metal content. They have been applied as valuable red ceramic components sintered at 700, 750, 800, 850, 900, and 950 °C, imparting flexural resistance of up to 17.6 MPa, water absorption at 950 °C of 6.53–10.45%, and linear shrinkage of 5.24–6.29%. Structure formation studies, performed by the XRD, SEM, EDS, and LAMMA methods demonstrated the synthesis of amorphous glassy material with the slight inclusion of mullite Al6Si2O13. Car production sludge and galvanic process glass waste act as intensifiers of the ceramics' structures formation processes. The ceramics' leaching and solubility tests by the atomic absorption spectroscopy method showed a robust chemical bonding of heavy metals from the hazardous raw materials in insoluble structures. According to Brazilian standards, the new materials can be used for production of tiles, bricks, blocks, and similar ceramic materials with high environmental efficiency. [ABSTRACT FROM AUTHOR]

In this work, a novel material candidate, containing Li2SiO3 (LS) ceramic and CaO–B2O3–SiO2 (CBS) glass for low-temperature co-fired ceramics (LTCC) application was developed via the traditional solid-state reaction process. It is shown that the addition of CBS glass significantly improves the sintering characteristics of LS + CBS glass–ceramic systems at low temperatures by lowering the sintering activation energy. Phase coexistence of the main crystalline phase of Li2SiO3 and minor trace of Li2Si2O5 phase was confirmed. The LS + 6 wt% CBS system presents excellent properties, sintered at 875 °C for 2 h: a εr value of 6.28, a Q × f value about 3527 GHz, a flexural strength 272 MPa, a CTE value of 7.35 × 10–6/°C, and a thermal conductivity λ > 10 W/m/K, denoting its promising future for LTCC substrate application. [ABSTRACT FROM AUTHOR]

As a nontraditional processing technology, electrochemical discharge machining (ECDM) can process glass and engineering ceramics precisely. This technology has proven to be a potential process for glass 3D microstructure. However, the key to expanding the application of ECDM is how to improve machining accuracy. This research conducted micro-hole and microgroove machining. Power voltage and frequency influence on hole processing efficiency, hole entrance diameter, and hole limit depth was explored. We considered four factors affecting ECDM—the voltage and frequency of the pulse power supply, the tool electrode feed rate, and the rotation speed. We studied their influence on the roughness of the microgrooves. The results show that machining efficiency, entrance diameter, and limit depth of micro-holes increased with the increase in voltage but decreased with the increase in power frequency. The results show that the roughness of microgrooves has an apparent positive correlation with the power voltage. In contrast, it had an evident negative correlation with the power frequency and electrode speed. The bottom surface roughness of microgrooves can be as minor as 0.605 μm. Various complex 3D microstructures on the glass surface by layer-by-layer method proved the great potential of ECDM. [ABSTRACT FROM AUTHOR]

A conventional melt quenching technique was used to successfully fabricate Mn2O3 -doped willemite glass-ceramics (Zn2SiO4:Mn3+) produced from the ZnO-SLS glasses. The results from XRD revealed that willemite crystallization is improved by increasing the sintering duration. It was revealed that, as the sintering duration progressed, the phase formation shifted from amorphous to α-Zn2SiO4 crystal. In addition, the structural growth of willemite phases can be seen using FTIR spectroscopy. The results of UV-Vis spectroscopy indicated that the intense absorption occurs in the UV zone, with wavelengths ranging from 250 nm to 400 nm, while the optical band gap showed a decreasing trend from 3.61 eV to 2.52 eV. These results perfectly established that Mn3+ dopant is potentially beneficial for producing willemite glass-ceramics for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Recent increasing interest in light guide plates (LGPs) based on the advanced manufacturing towards optoelectronics applications has emerged as a potential technology. The aim of this study was to estimate the optical characteristics on practical verification of laser-engraved glass light guide plate with concave microstructures. The case study can use the industrial ability of picosecond laser (pico-laser) technique, a type of ultrafast laser pulses, to directly engrave a glass sheet (Corning Iris® Glass) with functional concave microstructures for fabricating an LGP. Eight small pieces of samples with array of microstructures engraved on different processing conditions were made for measuring optical characteristics before and after the samples were etched by hydrofluoric acid. Here, the engraved 6-inch LGP structures can make light exit from the LGP uniformly. Additionally, the two optimized LGPs were put in a 7.8-inch backlight module where the measured results showed the uniformity of spatial luminance was 0.9. The study demonstrated the one-step process utilizing pico-laser technique, yielding for the design of microstructures of thinner large-sized liquid crystal display (LCD) products in the manufacturing of LGPs for lighted-up in a backlight unit (BLU). [ABSTRACT FROM AUTHOR]

Electrical properties of beryllium-alumino-tellurite glasses and glass–ceramics doped with iron ions were studied using impedance spectroscopy. The conductivity was measured over a wide frequency range from 10 mHz to 1 MHz and the temperature range from 213 to 473 K. The D.C. conductivity values showed a correlation with the Fe-ion concentration and ratio of iron ions on different valence states in the samples. On the basis of Jonscher universal dielectric response the temperature dependence of conductivity parameters were determined and compared to theoretical models collected by Elliott. In glasses, the conduction process was found to be due to the overlap polaron tunneling while in glass–ceramics the quantum mechanical tunneling between semiconducting crystallites of iron oxides is proposed. The D.C. conductivity was found not to follow Arrhenius relation. The Schnakenberg model was used to analyze the conductivity behavior and the polaron hopping energy and disorder energy were estimated. Additionally, the correlation between alumina dissolution and basicity of the melts was observed. [ABSTRACT FROM AUTHOR]

The effect of BaO on the crystallization, sintering, and properties of MgO-Al2O3-SiO2 glass–ceramics was investigated. The sintering kinetics suggested that doping BaO decreased the sintering activation energy and thus enhanced the densification of MAS glass–ceramics. DSC demonstrated that BaO increased the crystallization temperature of indialite and inhibited the precipitation of indialite. XRD indicated that the addition of BaO promoted the formation of (MgAl2Si3O10)0.6 and even stabilized the existence of (MgAl2Si3O10)0.6 phase. The precipitation of (MgAl2Si3O10)0.6 with high thermal expansion coefficient increased the internal stress and the mosaic structure of co-existed indialite and (MgAl2Si3O10)0.6 markedly improved mechanical properties. MAS glass–ceramics with 3 wt% BaO sintered at 950 °C showed good properties: εr = 6.01, tanδ = 2.5 × 10–3, σ = 310 MPa, φ = 109.3 GPa, and α = 4.52 × 10–6/°C. [ABSTRACT FROM AUTHOR]

Er3+/Yb3+ co-doped glass and glass ceramic samples were prepared by high temperature melting method, respectively, and the raw material ratio is: 6SrCO3·3.5MoO3·7Na2CO3·34SiO2·9NaF·40H3BO3· 0.5Sb2O3·3LuF3·0.15Yb2O3·0.03Er2O3. The XRD patterns were measured, and the results showed that SrMoO4 crystal phase were formed in the glass ceramic samples The Judd-Ofelt theory is used to study the spectral characteristics of glass ceramic samples, and the spectral line intensity parameters Ωλ (λ = 2, 4, 6) of Er3+ in the matrix material are calculated through absorption spectra. According to the spectral line intensity parameters, the experimental and theoretical oscillator strengths are calculated, and the root mean square deviation (δrms) between both of them is 4.37 × 10–6. And the parameters such as the transition probability, branching ratio and lifetime of Er3+ in the SrMoO4 crystal phase are obtained. Finally, the up-conversion luminescence spectra of glass sample and glass ceramic sample were measured under excitation of 980 nm laser, and three emission peaks located at 521, 545 and 654 nm were observed and all three emission peaks of glass ceramic sample are much higher than those of glass sample. According to the fitting curve between luminous intensity () and pump power (). It can be inferred that the up-conversion transition process of the Er3+/Yb3+ co-doped glass-ceramic samples belongs to two-photon absorption. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of grinding on some surface properties of two lithium disilicate-based glass-ceramics, one experimental new product denominated LaMaV Press (UFSCar-Brazil) and another commercial known as IPS e-max Press (Ivoclar), in the context of simulated clinical adjustment. Discs (N = 24, 12 mm in diameter) were separated into four groups: LaMaV Press with no grinding (E), LaMaV Press after grinding (EG), IPS e-max Press with no grinding (C), and IPS e-max Press after grinding (CG). A 0.1-mm deep grinding was carried out on EG and CG samples (final thickness of 1.4 mm) using a diamond stone in a low-speed device. The E and C samples had the same thickness. The effect of grinding on the sample surfaces was evaluated by X-ray diffraction, mechanical and optical profilometry, scanning electron microscopy, goniometry, and Vickers hardness. The mean roughness (Ra) was evaluated by Kruskal–Wallis and Student–Newman–Keuls statistics. The surface energy (SE) by the sessile drop method and Vickers hardness (VH) were analyzed using two-way ANOVA. The Ra medians were E = 1.69 µm, EG = 1.57 µm, C = 1.45 µm, and CG = 1.13 µm with p = 0.0284. The SE and VH were similar for all materials and treatments. Grinding smoothed the surfaces and did not significantly alter the hardness and surface energy of both LaMaV Press and IPS e-max Press. These glass-ceramics presented similar surface properties, and clinical adjustments can be implemented without loss of performance of both materials. [ABSTRACT FROM AUTHOR]

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Tungsten leaching residues are industrial wastes that are largely generated during commercial tungsten production. The residues have been classified as hazardous solid wastes due to the presence of toxic elements. On the other hand, the residues contain valuable elements, such as W, Mn, and Fe which can be recovered for economic benefit. To utilize the residue, a carbothermic reduction process was studied to achieve the effective utilization of the residue and sustainable development of the tungsten industry. Fe-W-Mn alloys and nontoxic slags were obtained successfully at 1450°C, and can be used to produce wear-resisting iron materials and glass–ceramics, respectively. The more effective metal–slag separation was achieved by controlling the MnO concentration of the slag, which impacted the liquidus temperature and the viscosity of the slag. This study confirmed a method for utilizing the tungsten residues, which could be a step toward practical industrial-scale techniques. [ABSTRACT FROM AUTHOR]

The features of laser drilling of highly porous composite ceramics consisting of aluminosilicate, glass, and a small addition of polystyrene (EPS) were studied experimentally. It was found that the formation of a liquid phase can contribute to the strengthening of ceramics. A list of factors determining the dynamics of hole formation is proposed. These include not only heating, melting, ablation, and ejection, previously known for metals and dense ceramics, but also a number of others: boiling-up of the mixture component with the lowest temperature of thermal decomposition and its departure from the affected zone; melt of less volatile components; compaction of ceramic adjoining the walls; glass transition of the liquid phase on cooling after irradiation. These effects depend on the density of the composite as well as on the viscosity of the liquefied material. [ABSTRACT FROM AUTHOR]

Glasses in the system xNd2O3–(46 − x)B2O3–27CaO–24.4Na2O–2.6 P2O5 (0 ≤ x ≤ 4 mol%) have been prepared via conventional melt quenching technique. X-ray diffraction spectra have showed that the amorphous structure is dominant in glasses of Nd2O3 concentrations ≤ 0.5 mol%. But formation of a more ordered structure is confirmed at higher Nd2O3 values. Result based on differential scanning calorimetry shows an increase in glass transition temperature (Tg) with increasing Nd2O3 at expense of B2O3. The measured density is found to be increased whereas the molar volume is decreased with increasing Nd2O3 content. The calculated molar volume (Vm) and free spaces (Vf) are both decreased due to filling process which is suggested to be carried out by Nd3+ of larger size than that of B3+. Decreasing of Vm and Vf can reflect the increase in bridging bonds in the glass network which in turns results in increasing of Tg of the investigated compositions. The thermal heat treatment process has no effect on state of crystal formation in glass containing 4 mol% Nd2O3. [ABSTRACT FROM AUTHOR]

This paper considers the design and industrial application of a circular grinding wheel of diameter 600 mm based on a multiple-use body with a groove along its diameter in which special elements are fastened. These elements are based on a binder with a diamond-bearing surface layer and are shaped as overlapping parallelepipeds with a clearance between the cutting layers of the elements. [ABSTRACT FROM AUTHOR]

Cordierite-based glass–ceramics for LTCC applications were prepared by traditional sintering method. And the effects of BaO addition on the crystallization, structure and dielectric properties were investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffractometer (XRD), dilatometer and impedance instrument. The DSC curves displayed that the glass transition temperature (Tg) slowly decreased with the BaO content increasing from 0 to 4 mol%. However, the onset of crystallization temperature (Tx) and crystallization peak temperature (Tc) showed the opposite trend. XRD analysis revealed that μ-cordierite was the major crystal phase for all the glass–ceramic samples, while α-cordierite precipitated as the minor crystal phase with BaO addition. As more BaO was added, the bulk density gradually increased, while the porosity decreased, indicating that BaO improved the sinterability of the glass samples. The dielectric constant showed minimum value with the addition of 2 mol% BaO, and the dielectric loss reached the minimum value when the content of BaO was 3 mol%. Wherein, after heated at 950 °C, glass–ceramics doped with 2 mol% BaO showed a dense structure, a relatively low dielectric constant (4.53), a low dielectric loss (2 × 10−3) at 1 MHz, and a proper CTE value (3.74 × 10–6/°C), which can be used to prepare LTCC materials. [ABSTRACT FROM AUTHOR]