The role of using frits in developing glazes for ceramics has increasingly received attention across a number of industrial ceramics fields in recent years. Over the past decade, the link between using frits for devel...The role of using frits in developing glazes for ceramics has increasingly received attention across a number of industrial ceramics fields in recent years. Over the past decade, the link between using frits for developing ceramics glazes and the reduction of financial costs has been at the center of much attention. Determining the impact of using frits in the local ceramics industry in Oman is important for the future study of this creative field. Using imported ready-made glazes, despite their long commercial success, is associated with a number of problems, including a shortage of suppliers, high costs, and logistical difficulties. Consequently, there is an urgent need to address the importance of developing glazes locally to help establish some workable solutions for the aforementioned problems. To date, no research studies have investigated using local Omani earthenware clays to make glazes by combining them with commercial frits using empirical laboratory methodologies. By developing low temperature chemical glaze recipes, the main aim of this study is to explore the possibilities of using Omani earthenware clays (OECs) and frits to create glazes that are suitable for local Omani ceramic works.展开更多
The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± ...The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± 10)°C, leads to obtaining transparent glasses, brown in color and with a non-hygroscopic appearance. The study of glasses dissolution rate, immersed in distilled water at 90°C for 24 days, indicates a considerable chemical durability. The increase in the Fe<sub>2</sub>O<sub>3</sub> content in the vitreous network to the detriment of PbO is a favorable factor for the chemical durability improvement. Different techniques have been used such as X-ray diffraction, infrared spectroscopy, DSC, SEM and density for the study of these glasses. These techniques have led to establish correlations between chemical and structural properties. Thus the results obtained confirmed the creation of P-O-M bonds (M = Pb, Fe) with a strongly covalent nature to the detriment of the hydrated P-O-P bonds and led to the formation, mainly, of pyrophosphate groups. The low melting point of Pb-O makes it possible to play an important role, at the same time, on the viscosity, on the equilibrium between the vitreous bath and the crystallites formed. The dissolution rate obtained is 100 times smaller than that of silicate glasses used as an alternative form for the vitrification of radioactive waste.展开更多
The underground disposal of waste arising from the nuclear industry needs constant evaluation in order to improve upon it through minimizing the volume and cost by reducing the amount of glass used without compromisin...The underground disposal of waste arising from the nuclear industry needs constant evaluation in order to improve upon it through minimizing the volume and cost by reducing the amount of glass used without compromising the safety of any leakage from the radioactive waste form. The immobilization of the spent resin (NRW-40) in borosilicate glass was investigated to meet the acceptance criteria for disposal of nuclear waste. The organic mixed bed resin in granular form was used as a waste target. The analysis of surrogate resin doped with radioactive and non-radioactive cesium (Cs) and cobalt (Co) was carried out to investigate their thermal and chemical properties and their compatibility with an alkaline borosilicate glass. The thermal analysis indicates that the structural damage caused by 1 mSv gamma radiation to the radioactive resin has altered its properties in comparison with the non-radioactive resin, same amount of cesium (8.88 wt%) and cobalt (1.88 wt%) were used in both resins. The immobilization of residue shows that the excess sulfur in the residue caused phase crystallization in the final glass matrix. It was found that the volatilization of Cs-137 and Co-60 from the successful radioactive resin-glass matrix (HG-3-IER-500) were more than that in the non-radioactive resin-glass matrix (HG-3-IEX-500). The study demonstrates comprehensive experimental and analytical works and shows that it is possible to minimise the volume of the waste while keeping the required safety levels, however further research needs to be carried out in this area.展开更多
Glasses and glass ceramics in the system xCeO<sub>2·</sub>(50 - x)PbO·50B<sub>2</sub>O<sub>3</sub> (0 ≤ x ≤ 50) have been studied, for the first time, by NMR a...Glasses and glass ceramics in the system xCeO<sub>2·</sub>(50 - x)PbO·50B<sub>2</sub>O<sub>3</sub> (0 ≤ x ≤ 50) have been studied, for the first time, by NMR and FTIR techniques. Effect of CeO<sub>2</sub> substitution with PbO on NMR parameters has been discussed in terms of changing both boron and cerium coordination. The quantitative fraction of four coordinated boron (N<sub>4</sub>) has been simply determined from <sup>11</sup>B NMR spectroscopy. On the other hand, the fraction of total tetrahedral structural units B<sub>4</sub> (BO<sub>4</sub> + PbO<sub>4</sub> + CeO<sub>4</sub>) is obtained from FTIR spectral analysis. It is not possible to get the fraction of cerium oxide directly from the applied spectroscopic tools. Therefore, a simple approach is applied, for the first time, to determine CeO<sub>4</sub> fraction by using the different criteria of both <sup>11</sup>B NMR and FTIR spectroscopy. The fraction of B<sub>4</sub> species is equal to N<sub>4</sub>, within the experimental error, of the same glasses in the composition region of up to 10 mol% CeO<sub>2</sub>. On the other hand, there is a clear difference between both N<sub>4</sub> and B<sub>4</sub> values in glasses of higher CeO<sub>2 </sub>content (>10 mol%). The related difference showed a linear increasing trend with increasing the content of CeO<sub>2</sub> in the glass. This was discussed on the bases of structural role of CeO<sub>2</sub> which acts as a glass former in the region >10 mol%, while, at lower concentration, it consumed as a glass modifier.展开更多
Breakage patterns, residual stress, and fractured surfaces on tempered glasses are investigated to find the correlation among glass thickness, tempered level, and the number of fragments, particularly when the glass t...Breakage patterns, residual stress, and fractured surfaces on tempered glasses are investigated to find the correlation among glass thickness, tempered level, and the number of fragments, particularly when the glass thickness is less than 4 mm. Relatively thin glasses require high compressive stress for producing fragments, and the required compressive stress is increased with decreasing glass thickness (3.2 to 2.1 mm). By analyzing the residual stress of glasses before and after the fragmentation test, we observe that a relatively thin glass spends more stored energy to generate a new fracture surface and stores less energy for the second cracking as compared to thick glasses. Fractography shows that all glasses have a similar characterization on the fractured surface irrespective of glass thickness. However, the only dif- ference is the depth of the compressive layer. By reducing the depth of the compressive layer to less than approx. 20% of the glass thickness, it is observed that the possibility of producing small fragments is dramatically decreased. There- fore, this study confirms that the compressive stress and its depth are essential as key factors contributing to the achievement of a relatively high fragmentation using a thin glass.展开更多
This paper reports on different physical and optical properties of Nd3+-doped bismuth borate glasses. The glasses containing Nd3+ in (25 - x)Bi2O3:20Li2O:20ZnO:35B2O3:xNd2O3 (where x = 1, 1.5, 2 mol%) have been prepar...This paper reports on different physical and optical properties of Nd3+-doped bismuth borate glasses. The glasses containing Nd3+ in (25 - x)Bi2O3:20Li2O:20ZnO:35B2O3:xNd2O3 (where x = 1, 1.5, 2 mol%) have been prepared by melt-quenching method. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The physical parameters like dielectric constant, refractive index, ionic concentration, oxygen-packing density, inter ionic distance, polaronradius, reflection loss, energy gap, molar refractivity, molar polarizability, electronic polarizability, optical basicity and field strength are computed. On the basis of the measured values of the density and refractive index, the Nd3+ ion concentration in glasses, the polarizability of oxide ions and optical basicity were theoretically determined. The theoretical value of average electronic polarizability and oxide ion polarizability were calculated by using Lorentz-Lorenz formula. Theoretical optical basicity of the glasses is evaluated based on equation proposed by Duffy and Ingram. The metallization criterion has also been calculated on the basis of refractive index and energy gap. The large value of metallization criterion indicates that the glass materials are insulators. The results obtained predict the nature of bonding in the present glasses and provide basis for developing new nonlinear optical material.展开更多
As defined by the American Concrete Institute (ACI), alternative supplementary cementitious materials (ASCMs) and local materials are very important in concrete sustainability. As an ASCM, glass powder (GP) shows exce...As defined by the American Concrete Institute (ACI), alternative supplementary cementitious materials (ASCMs) and local materials are very important in concrete sustainability. As an ASCM, glass powder (GP) shows excellent pozzolanic properties. This paper focuses on characterization and the effect of GP on concrete properties compared to those of Class F fly ash (FFA) and ground granulated blast furnace slag (GGBS). Concrete incorporating 0, 20 and 30% of GP and other concrete mixes containing 30% of FFA or GGBS were cast. The concrete mixes considered in this study have water to binder (w/b) mass ratio ranging from 0.35 to 0.65. The mechanical properties such as compressive strength and durability including chloride ions permeability and chloride ions diffusion are evaluated. The results show that GP develops effects on mechanical properties similar to those of FFA and performs better than GGBS and FFA in terms of permeability reduction. GP reduces dramatically chloride permeability of concrete regardless w/b ratio, favoring an improvement of the concrete durability. Because of the interesting permeability developed by concretes incorporating GP, its use as an ASCM is promising.展开更多
<div style="text-align:justify;"> The values of refractive index (<i>n</i>) for silicate glasses (silica, soda lime and borosilicate 7059) are decreased from 1.5119 to 1.5111, 1.5086 to 1.5...<div style="text-align:justify;"> The values of refractive index (<i>n</i>) for silicate glasses (silica, soda lime and borosilicate 7059) are decreased from 1.5119 to 1.5111, 1.5086 to 1.5065 and 1.5296 to 1.5281, respectively;and the optical band gap (<i>E<sub>g</sub></i>) is increased from 9.8 to 9.81 eV, 9.845 to 9.88 eV and 9.56 to 9.58 eV, respectively over the temperature range 295 - 473 K using ellipsometer at wavelength 632.8 nm. While <i>n</i> is decreased from 1.5276 to 1.5274, 1.5074 to 1.5070 and from 1.5283 to 1.5281, respectively;and <i>E<sub>g</sub></i> is increased from 9.59 to 9.592 eV, 9.862 to 9.870 eV, and 9.574 to 9.58 eV, respectively over the temperature range 297 - 322 K using Abbe refractometer at wavelength 589.3 nm. The values of oxide ion polarizability [<i>α</i><sub>o2-</sub> <span "="">(<i>n</i>) and</span> <i>α</i><sub>o2-</sub><span "=""></span><span "="">(<i>E<sub>g</sub></i>)] regarding silica, soda lime and borosilicate 7059 glasses are decreased from 1.3427 to 1.3408, 1.6014 to 1.5941, 1.4329 to 1.4193, respectively over the temperature range 295 - 473 K using ellipsometer;and are decreased from 1.3786 to 1.3764, 1.5991 to 1.5969, 1.4297 to 1.4191, respectively over the temperature range 297 - 322 K using Abbe refractometer. Similarly, the values of optical basicity [<i>A</i></span> <span "="">(<i>n</i>) and <i>A</i></span> <span "="">(<i>E<sub>g</sub></i>)] of silica, soda lime, and borosilicate 7059 glasses are decreased from 0.4272 to 0.4245, 0.6271 to 0.6224, 0.5045 to 0.4933, respectively over the temperature range 295 - 473 K using ellipsometer;and are decreased from 0.4586 to 0.4567, 0.6256 to 0.6242, 0.5018 to 0.4930, respectively over the temperature range 297 - 322 K using Abbe refractometer. <b>Further,</b> we have found that for silica, soda lime and borosilicate 7059, the values of electronegativity (<i>ξ<sub>1av</sub></i>)</span><span minion="" pro="" capt","serif";"=""> QUOTE </span><span cambria="" math","serif";font-style:italic;"=""></span><span cambria="展开更多
Alumina-magnesia refractory castables have been widely used in the wall and bottom impact pad of steel ladles. The properties of alumina-magnesia refractory castables with SnO2 additive in 0 - 5 wt% range were investi...Alumina-magnesia refractory castables have been widely used in the wall and bottom impact pad of steel ladles. The properties of alumina-magnesia refractory castables with SnO2 additive in 0 - 5 wt% range were investigated. The phase composition, microstructure, physical and mechanical properties of these refractories were studied. The results showed that the addition of SnO2 could have a great influence on the properties of alumina-magnesia refractory castables. The expansion, apparent porosity and strength of refractories with SnO2 were all more prominent than those of reference samples, which were attributed to the formation of CA6 and enhanced bonding. Meanwhile SnO2 could react with spinel and CA6 to form solid solution.展开更多
The structure of borosilicate glasses of composition 30Na<sub>2</sub>O-2Al<sub>2</sub>O<sub>3</sub>-25SiO<sub>2</sub>-xFe<sub>2</sub>O<sub>3</sub>...The structure of borosilicate glasses of composition 30Na<sub>2</sub>O-2Al<sub>2</sub>O<sub>3</sub>-25SiO<sub>2</sub>-xFe<sub>2</sub>O<sub>3</sub><sub></sub> (43-x) B<sub>2</sub>O<sub>3</sub> has been investigated in the composition range of 0.5 20 mol% Fe<sub>2</sub>O<sub>3</sub>. <sup>27</sup>Al, <sup>11</sup>B, <sup>29 </sup>Si MAS NMR and FTIR spectroscopies have been used to measure the fraction of different structural species in the glasses. It is evidenced from NMR data that both sodium and Fe<sub>2</sub>O<sub>3</sub> (in low region up to 7 mol%) are the main glass modifier. Structural determination for borosilicate glasses with a high content of (Fe<sub>2</sub>O<sub>3</sub>) was carried out by FTIR spectroscopy, where both <sup>11</sup>B and <sup>29</sup>Si MAS NMR are impossible because of the high quantities of paramagnetic iron (III) species present. NMR analysis was performed on borosilicate glasses containing up to 7 mol% Fe<sub>2</sub>O<sub>3</sub> and the N<sub>4</sub> values obtained by FTIR spectroscopy agree within error with the <sup>11</sup>B NMR results of the same glass samples. Fe<sub>2</sub>O<sub>3</sub> is a main glass modifier in the low-Fe<sub>2</sub>O<sub>3</sub>-content region (≤6 mol%). On other hand, it plays the role of glass former at higher content of Fe<sub>2</sub>O<sub>3</sub>. Increasing both N<sub>4 </sub>of boron tetrahedral units and chemical shift of silicon nuclei to reach maxima at 5 mol% Fe<sub>2</sub>O<sub>3</sub> confirms the role of Fe<sub>2</sub>O<sub>3</sub> as a glass modifier in the low composition region. On the other hand, fast decrease in N<sub>4</sub> with further increasing Fe<sub>2</sub>O<sub>3</sub> contents ≥6 mol%) is an evidence for iron oxide to inter the glass network as a network former.展开更多
Five mixtures (M1 to M5) of silica-alumina geomaterials and two varieties of alumina (AP and AR) were used for the elaboration of mullite refractory materials between 1500℃ and 1600℃. An X-ray diffraction (XRD) anal...Five mixtures (M1 to M5) of silica-alumina geomaterials and two varieties of alumina (AP and AR) were used for the elaboration of mullite refractory materials between 1500℃ and 1600℃. An X-ray diffraction (XRD) analysis showed that the refractory samples are composed of mullite, corundum and silica. The length of the mullite crystals was measured by a method of image analysis of scanning electron microscopy (SEM). Chemical and mechanical properties of these materials were investigated and correlated with their microstructure. Resistance towards Acid Attack test showed that the refractory samples present good resistance, as well as, the alumina powder AR obtained from waste of silica-alumina bricks proves to be efficient for an eventual use.展开更多
The key research and development steps for bioactive glass (45S5 Bioglass) are documented from the date of discovery in 1969 through FDA approvals of the first dental, ENT, maxillo-facial and orthopedic clinical produ...The key research and development steps for bioactive glass (45S5 Bioglass) are documented from the date of discovery in 1969 through FDA approvals of the first dental, ENT, maxillo-facial and orthopedic clinical products. Understanding the mechanisms and quantifying the rapid surface reactions to form a bone-bonding hydroxyl-carbonate apatite (HCA) layer on the bioactive glass in contact with living bone was a vital part of the early development of this class of biomaterials. A key later discovery was enhanced osteogenesis and in situ bone regeneration by controlled release of ionic dissolution products from the bioactive glass particulates that leads to up-regulation and activation of seven families of genes, a process called osteostimulation.展开更多
A set of borophosphate glasses doped with alkali and transition metal (TM) ions have been synthesized. The glasses were carried through;annealing, XRD, density, DC conductivity studies. Molar volume and density varied...A set of borophosphate glasses doped with alkali and transition metal (TM) ions have been synthesized. The glasses were carried through;annealing, XRD, density, DC conductivity studies. Molar volume and density varied nonlinearly. High temperature activation energy is analysed taking into consideration of Mott’s SPH model. The low temperature electrical conductivity was analysed by Mott and Greaves VRH. Several polaron hopping related parameters at high temperature region and density of states at low temperature region were computed. The high temperature DC activation energy measured by conductivity, calculated numerous pertained parameters varied nonlinearly with mole fraction of vanadium content. The Study exhibits DC electrical conduction is due to both alkali and transition metal ions and thus confirms the mixed conductivity. A crossover conduction mechanism from the ionic dominant region to polaronic predominant region has been also observed. Studies revealed the single transition effect at 0.4 mol fraction of V<sub>2</sub>O<sub>5</sub> content.展开更多
This article aims to investigate the possibility to turn the multiferroic orders and magnetocapacitance effect close to/above room temperature in nanosized GaFeO3 ceramics by a sol-gel preparation method and substitut...This article aims to investigate the possibility to turn the multiferroic orders and magnetocapacitance effect close to/above room temperature in nanosized GaFeO3 ceramics by a sol-gel preparation method and substitution with non-magnetic Zn atoms. Therefore, in this work, we have synthesized a series of nanocrystalline Ga1-xZnxFeO3(GZFO, x = 0, 0.01, 0.05 and 0.1) ceramic samples and study the effect of Zn substitution on their structural, magnetic, and electric properties. All the GZFO samples have an orthorhombic structure with Pc21n space group and the value of lattice parameters increase systematically with increasing Zn concentration. Interestingly, it shows that magnetic and electric properties are strongly dependent on the Zn substitution concentration. Based on the results of temperature-dependent magnetizations, M(T), it is observed that with increasing Zn-content up to 0.10, the ferrimagnetic transition temperature (TC) increases from 306 to 320 K. It is also found that the nanocrystalline Zn-doped GaFeO3 (GFO) samples exhibit the characteristics of ferroelectricity at room temperature. Furthermore, the?magnetization, ferroelectric polarization and magnetocapacitance of Zn-doped GFO nanosized ceramics are enhanced compared to those of the pristine sample of GFO ferrite. These results open wide perspectives for the applications of room temperature multiferroic devices.展开更多
The reactivity of the recycled glass powder (GP) in a cementitious medium has been studied over time by means of X-ray diffraction and thermal gravimetric analysis. Two different mixtures based on cement/glass powder ...The reactivity of the recycled glass powder (GP) in a cementitious medium has been studied over time by means of X-ray diffraction and thermal gravimetric analysis. Two different mixtures based on cement/glass powder (0 or 20 wt% GP) and lime/glass powder (70 wt% GP) were considered. Analysis revealed the coexistence of both hydration and pozzolanic reaction during the hardening of the mortars. At young age, the cement hydration would prevail over the pozzolanic one resulting in a decrease of physico-chemical </span></span><a name="_GoBack"></a><span><span><span style="font-family:"">and mechanical properties of the material due to the dilution effect. The pozzolanic reaction that predominates from 91 days, would induce the formation of supplementary C-S-H leading to improve the material properties.展开更多
A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and <...A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and <sup><span style="font-size:12px;font-family:Verdana;">31</span></sup><span style="font-family:Verdana;">P NMR spectroscopy. The microstructures of samples contain <1 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">are amorphous in nature. More addition of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> transforms the glass to glass-ceramics without thermal annealing. The morphological change of the microstructure of these materials was followed by transmission electron microscopy (TEM). The obtained results have revealed that the addition of more than 0.8 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> can promote nucleation and crystallization routes that </span></span><span style="font-family:Verdana;">are </span><span style="font-family:;" "=""><span style="font-family:Verdana;">combined with the establishment of diverse crystalline phases. Glasses with lower contents of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">showed no tendency to crystallization. The crystals of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> containing glasses were spheroid like morphology that </span></span><span style="font-family:Verdana;">was </span><span style="font-family:Verdana;">assigned to the three-dimensional fast growth of the well-formed structural species in the boro-apatite phase. In addition, the cerium free glass is characterized by particle-like morphology. Then the growth of spheroid species展开更多
The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray d...The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.展开更多
Transparent conducting films of zinc oxide and indium-doped zinc oxide have been prepared by a simple and economical sol-gel technique. This process is feasible for the fabrication of high quality TCO thin films when ...Transparent conducting films of zinc oxide and indium-doped zinc oxide have been prepared by a simple and economical sol-gel technique. This process is feasible for the fabrication of high quality TCO thin films when the processing parameters are optimized. It was found that the out-diffusion of oxygen during the vacuum annealing step was a crucial factor to prepare thin layer with superior properties. Annealing lowers the resistivity down to 4.7 10-3?Ω·cm for the 1 at.% doped films due to the liberation of high-valency In-dopants and the enhanced film density. At high indium concentrations, the free electron density stabilizes because an increasing number of dopant atoms form some kinds of neutral defects. The neutralized indium atoms do not contribute free electrons. The feasibility to deposit highly transparent ZnO thin films has been demonstrated.展开更多
The structure of glasses in the system of xCeO2(100?-?x)B2O3, x = 30, 40, 50 mol% CeO2 has been explored for the first time by correlation between data obtained from XRD, FTIR and 11B NMR analyses. NMR spectroscopy an...The structure of glasses in the system of xCeO2(100?-?x)B2O3, x = 30, 40, 50 mol% CeO2 has been explored for the first time by correlation between data obtained from XRD, FTIR and 11B NMR analyses. NMR spectroscopy andFTIR spectroscopy have confirmed that transformation rate of BO3 to BO4 groups is reduced by CeO2 addition.The concentration of Ce4-O-Ce4 is increased at the expense of both B4-O-Ce4 and B3-O-B4 linkages. Boron atoms are mainly coordinated with Ce4 sites as second neighbors due to increasing CeO4 species with further increase of CeO2 concentration. Increasing B4 fraction is considered due to forming of CeO4 with rate higher than that of BO4 units. The change of chemical shift of 11B nuclei upon exchanging B2O3 with CeO2 confirms that the central boron atoms would be coordinated with tetrahedral cerium atoms as second neighbors. The X-ray diffraction of cerium rich glass is clearly indicated that the formation of crystalline phases refers to CeO4, CeBO3and Ce(BO2)3 species.展开更多
In this work the effect of the type of the bonding interlayer (polyvinyl butyral (PVB) or Ethyl Vinyl Acetate (EVA)), number of bonding layers, and the position and the thickness of the Glass plates on the maximum loa...In this work the effect of the type of the bonding interlayer (polyvinyl butyral (PVB) or Ethyl Vinyl Acetate (EVA)), number of bonding layers, and the position and the thickness of the Glass plates on the maximum load capacity and absorbed energy by laminated glass. Furthermore, this investigation presents a mathematical model that relates the maximum force capacity of the glass laminated structure to the glass plate thickness, type and thickness of the inter-layer regardless the position of the fixed glass plate. Both practical work results and the theoretical model indicate that the maximum load capacity of laminated glass bonded with either PVB or EVA decreases as the interlayer thickness increases. Moreover, the maximum load capacity for the glasses bonded with EVA is greater than those for the PVB bonded ones under the same conditions. On the other hand, it was observed that that laminated glass absorbed energy increases with the increase of the interlayer thickness and the increase of glass plate thickness.展开更多
文摘The role of using frits in developing glazes for ceramics has increasingly received attention across a number of industrial ceramics fields in recent years. Over the past decade, the link between using frits for developing ceramics glazes and the reduction of financial costs has been at the center of much attention. Determining the impact of using frits in the local ceramics industry in Oman is important for the future study of this creative field. Using imported ready-made glazes, despite their long commercial success, is associated with a number of problems, including a shortage of suppliers, high costs, and logistical difficulties. Consequently, there is an urgent need to address the importance of developing glazes locally to help establish some workable solutions for the aforementioned problems. To date, no research studies have investigated using local Omani earthenware clays to make glazes by combining them with commercial frits using empirical laboratory methodologies. By developing low temperature chemical glaze recipes, the main aim of this study is to explore the possibilities of using Omani earthenware clays (OECs) and frits to create glazes that are suitable for local Omani ceramic works.
文摘The synthesis for glasses series xFe<sub>2</sub>O<sub>3</sub>-(45-x)PbO-55P<sub>2</sub>O<sub>5</sub>, (with 0 ≤ x ≤ 20;mol%) carried out in a temperature (1050 ± 10)°C, leads to obtaining transparent glasses, brown in color and with a non-hygroscopic appearance. The study of glasses dissolution rate, immersed in distilled water at 90°C for 24 days, indicates a considerable chemical durability. The increase in the Fe<sub>2</sub>O<sub>3</sub> content in the vitreous network to the detriment of PbO is a favorable factor for the chemical durability improvement. Different techniques have been used such as X-ray diffraction, infrared spectroscopy, DSC, SEM and density for the study of these glasses. These techniques have led to establish correlations between chemical and structural properties. Thus the results obtained confirmed the creation of P-O-M bonds (M = Pb, Fe) with a strongly covalent nature to the detriment of the hydrated P-O-P bonds and led to the formation, mainly, of pyrophosphate groups. The low melting point of Pb-O makes it possible to play an important role, at the same time, on the viscosity, on the equilibrium between the vitreous bath and the crystallites formed. The dissolution rate obtained is 100 times smaller than that of silicate glasses used as an alternative form for the vitrification of radioactive waste.
文摘The underground disposal of waste arising from the nuclear industry needs constant evaluation in order to improve upon it through minimizing the volume and cost by reducing the amount of glass used without compromising the safety of any leakage from the radioactive waste form. The immobilization of the spent resin (NRW-40) in borosilicate glass was investigated to meet the acceptance criteria for disposal of nuclear waste. The organic mixed bed resin in granular form was used as a waste target. The analysis of surrogate resin doped with radioactive and non-radioactive cesium (Cs) and cobalt (Co) was carried out to investigate their thermal and chemical properties and their compatibility with an alkaline borosilicate glass. The thermal analysis indicates that the structural damage caused by 1 mSv gamma radiation to the radioactive resin has altered its properties in comparison with the non-radioactive resin, same amount of cesium (8.88 wt%) and cobalt (1.88 wt%) were used in both resins. The immobilization of residue shows that the excess sulfur in the residue caused phase crystallization in the final glass matrix. It was found that the volatilization of Cs-137 and Co-60 from the successful radioactive resin-glass matrix (HG-3-IER-500) were more than that in the non-radioactive resin-glass matrix (HG-3-IEX-500). The study demonstrates comprehensive experimental and analytical works and shows that it is possible to minimise the volume of the waste while keeping the required safety levels, however further research needs to be carried out in this area.
文摘Glasses and glass ceramics in the system xCeO<sub>2·</sub>(50 - x)PbO·50B<sub>2</sub>O<sub>3</sub> (0 ≤ x ≤ 50) have been studied, for the first time, by NMR and FTIR techniques. Effect of CeO<sub>2</sub> substitution with PbO on NMR parameters has been discussed in terms of changing both boron and cerium coordination. The quantitative fraction of four coordinated boron (N<sub>4</sub>) has been simply determined from <sup>11</sup>B NMR spectroscopy. On the other hand, the fraction of total tetrahedral structural units B<sub>4</sub> (BO<sub>4</sub> + PbO<sub>4</sub> + CeO<sub>4</sub>) is obtained from FTIR spectral analysis. It is not possible to get the fraction of cerium oxide directly from the applied spectroscopic tools. Therefore, a simple approach is applied, for the first time, to determine CeO<sub>4</sub> fraction by using the different criteria of both <sup>11</sup>B NMR and FTIR spectroscopy. The fraction of B<sub>4</sub> species is equal to N<sub>4</sub>, within the experimental error, of the same glasses in the composition region of up to 10 mol% CeO<sub>2</sub>. On the other hand, there is a clear difference between both N<sub>4</sub> and B<sub>4</sub> values in glasses of higher CeO<sub>2 </sub>content (>10 mol%). The related difference showed a linear increasing trend with increasing the content of CeO<sub>2</sub> in the glass. This was discussed on the bases of structural role of CeO<sub>2</sub> which acts as a glass former in the region >10 mol%, while, at lower concentration, it consumed as a glass modifier.
文摘Breakage patterns, residual stress, and fractured surfaces on tempered glasses are investigated to find the correlation among glass thickness, tempered level, and the number of fragments, particularly when the glass thickness is less than 4 mm. Relatively thin glasses require high compressive stress for producing fragments, and the required compressive stress is increased with decreasing glass thickness (3.2 to 2.1 mm). By analyzing the residual stress of glasses before and after the fragmentation test, we observe that a relatively thin glass spends more stored energy to generate a new fracture surface and stores less energy for the second cracking as compared to thick glasses. Fractography shows that all glasses have a similar characterization on the fractured surface irrespective of glass thickness. However, the only dif- ference is the depth of the compressive layer. By reducing the depth of the compressive layer to less than approx. 20% of the glass thickness, it is observed that the possibility of producing small fragments is dramatically decreased. There- fore, this study confirms that the compressive stress and its depth are essential as key factors contributing to the achievement of a relatively high fragmentation using a thin glass.
文摘This paper reports on different physical and optical properties of Nd3+-doped bismuth borate glasses. The glasses containing Nd3+ in (25 - x)Bi2O3:20Li2O:20ZnO:35B2O3:xNd2O3 (where x = 1, 1.5, 2 mol%) have been prepared by melt-quenching method. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The physical parameters like dielectric constant, refractive index, ionic concentration, oxygen-packing density, inter ionic distance, polaronradius, reflection loss, energy gap, molar refractivity, molar polarizability, electronic polarizability, optical basicity and field strength are computed. On the basis of the measured values of the density and refractive index, the Nd3+ ion concentration in glasses, the polarizability of oxide ions and optical basicity were theoretically determined. The theoretical value of average electronic polarizability and oxide ion polarizability were calculated by using Lorentz-Lorenz formula. Theoretical optical basicity of the glasses is evaluated based on equation proposed by Duffy and Ingram. The metallization criterion has also been calculated on the basis of refractive index and energy gap. The large value of metallization criterion indicates that the glass materials are insulators. The results obtained predict the nature of bonding in the present glasses and provide basis for developing new nonlinear optical material.
基金the SAQ for its valuable financial support for this project.
文摘As defined by the American Concrete Institute (ACI), alternative supplementary cementitious materials (ASCMs) and local materials are very important in concrete sustainability. As an ASCM, glass powder (GP) shows excellent pozzolanic properties. This paper focuses on characterization and the effect of GP on concrete properties compared to those of Class F fly ash (FFA) and ground granulated blast furnace slag (GGBS). Concrete incorporating 0, 20 and 30% of GP and other concrete mixes containing 30% of FFA or GGBS were cast. The concrete mixes considered in this study have water to binder (w/b) mass ratio ranging from 0.35 to 0.65. The mechanical properties such as compressive strength and durability including chloride ions permeability and chloride ions diffusion are evaluated. The results show that GP develops effects on mechanical properties similar to those of FFA and performs better than GGBS and FFA in terms of permeability reduction. GP reduces dramatically chloride permeability of concrete regardless w/b ratio, favoring an improvement of the concrete durability. Because of the interesting permeability developed by concretes incorporating GP, its use as an ASCM is promising.
文摘<div style="text-align:justify;"> The values of refractive index (<i>n</i>) for silicate glasses (silica, soda lime and borosilicate 7059) are decreased from 1.5119 to 1.5111, 1.5086 to 1.5065 and 1.5296 to 1.5281, respectively;and the optical band gap (<i>E<sub>g</sub></i>) is increased from 9.8 to 9.81 eV, 9.845 to 9.88 eV and 9.56 to 9.58 eV, respectively over the temperature range 295 - 473 K using ellipsometer at wavelength 632.8 nm. While <i>n</i> is decreased from 1.5276 to 1.5274, 1.5074 to 1.5070 and from 1.5283 to 1.5281, respectively;and <i>E<sub>g</sub></i> is increased from 9.59 to 9.592 eV, 9.862 to 9.870 eV, and 9.574 to 9.58 eV, respectively over the temperature range 297 - 322 K using Abbe refractometer at wavelength 589.3 nm. The values of oxide ion polarizability [<i>α</i><sub>o2-</sub> <span "="">(<i>n</i>) and</span> <i>α</i><sub>o2-</sub><span "=""></span><span "="">(<i>E<sub>g</sub></i>)] regarding silica, soda lime and borosilicate 7059 glasses are decreased from 1.3427 to 1.3408, 1.6014 to 1.5941, 1.4329 to 1.4193, respectively over the temperature range 295 - 473 K using ellipsometer;and are decreased from 1.3786 to 1.3764, 1.5991 to 1.5969, 1.4297 to 1.4191, respectively over the temperature range 297 - 322 K using Abbe refractometer. Similarly, the values of optical basicity [<i>A</i></span> <span "="">(<i>n</i>) and <i>A</i></span> <span "="">(<i>E<sub>g</sub></i>)] of silica, soda lime, and borosilicate 7059 glasses are decreased from 0.4272 to 0.4245, 0.6271 to 0.6224, 0.5045 to 0.4933, respectively over the temperature range 295 - 473 K using ellipsometer;and are decreased from 0.4586 to 0.4567, 0.6256 to 0.6242, 0.5018 to 0.4930, respectively over the temperature range 297 - 322 K using Abbe refractometer. <b>Further,</b> we have found that for silica, soda lime and borosilicate 7059, the values of electronegativity (<i>ξ<sub>1av</sub></i>)</span><span minion="" pro="" capt","serif";"=""> QUOTE </span><span cambria="" math","serif";font-style:italic;"=""></span><span cambria="
文摘Alumina-magnesia refractory castables have been widely used in the wall and bottom impact pad of steel ladles. The properties of alumina-magnesia refractory castables with SnO2 additive in 0 - 5 wt% range were investigated. The phase composition, microstructure, physical and mechanical properties of these refractories were studied. The results showed that the addition of SnO2 could have a great influence on the properties of alumina-magnesia refractory castables. The expansion, apparent porosity and strength of refractories with SnO2 were all more prominent than those of reference samples, which were attributed to the formation of CA6 and enhanced bonding. Meanwhile SnO2 could react with spinel and CA6 to form solid solution.
文摘The structure of borosilicate glasses of composition 30Na<sub>2</sub>O-2Al<sub>2</sub>O<sub>3</sub>-25SiO<sub>2</sub>-xFe<sub>2</sub>O<sub>3</sub><sub></sub> (43-x) B<sub>2</sub>O<sub>3</sub> has been investigated in the composition range of 0.5 20 mol% Fe<sub>2</sub>O<sub>3</sub>. <sup>27</sup>Al, <sup>11</sup>B, <sup>29 </sup>Si MAS NMR and FTIR spectroscopies have been used to measure the fraction of different structural species in the glasses. It is evidenced from NMR data that both sodium and Fe<sub>2</sub>O<sub>3</sub> (in low region up to 7 mol%) are the main glass modifier. Structural determination for borosilicate glasses with a high content of (Fe<sub>2</sub>O<sub>3</sub>) was carried out by FTIR spectroscopy, where both <sup>11</sup>B and <sup>29</sup>Si MAS NMR are impossible because of the high quantities of paramagnetic iron (III) species present. NMR analysis was performed on borosilicate glasses containing up to 7 mol% Fe<sub>2</sub>O<sub>3</sub> and the N<sub>4</sub> values obtained by FTIR spectroscopy agree within error with the <sup>11</sup>B NMR results of the same glass samples. Fe<sub>2</sub>O<sub>3</sub> is a main glass modifier in the low-Fe<sub>2</sub>O<sub>3</sub>-content region (≤6 mol%). On other hand, it plays the role of glass former at higher content of Fe<sub>2</sub>O<sub>3</sub>. Increasing both N<sub>4 </sub>of boron tetrahedral units and chemical shift of silicon nuclei to reach maxima at 5 mol% Fe<sub>2</sub>O<sub>3</sub> confirms the role of Fe<sub>2</sub>O<sub>3</sub> as a glass modifier in the low composition region. On the other hand, fast decrease in N<sub>4</sub> with further increasing Fe<sub>2</sub>O<sub>3</sub> contents ≥6 mol%) is an evidence for iron oxide to inter the glass network as a network former.
文摘Five mixtures (M1 to M5) of silica-alumina geomaterials and two varieties of alumina (AP and AR) were used for the elaboration of mullite refractory materials between 1500℃ and 1600℃. An X-ray diffraction (XRD) analysis showed that the refractory samples are composed of mullite, corundum and silica. The length of the mullite crystals was measured by a method of image analysis of scanning electron microscopy (SEM). Chemical and mechanical properties of these materials were investigated and correlated with their microstructure. Resistance towards Acid Attack test showed that the refractory samples present good resistance, as well as, the alumina powder AR obtained from waste of silica-alumina bricks proves to be efficient for an eventual use.
文摘The key research and development steps for bioactive glass (45S5 Bioglass) are documented from the date of discovery in 1969 through FDA approvals of the first dental, ENT, maxillo-facial and orthopedic clinical products. Understanding the mechanisms and quantifying the rapid surface reactions to form a bone-bonding hydroxyl-carbonate apatite (HCA) layer on the bioactive glass in contact with living bone was a vital part of the early development of this class of biomaterials. A key later discovery was enhanced osteogenesis and in situ bone regeneration by controlled release of ionic dissolution products from the bioactive glass particulates that leads to up-regulation and activation of seven families of genes, a process called osteostimulation.
文摘A set of borophosphate glasses doped with alkali and transition metal (TM) ions have been synthesized. The glasses were carried through;annealing, XRD, density, DC conductivity studies. Molar volume and density varied nonlinearly. High temperature activation energy is analysed taking into consideration of Mott’s SPH model. The low temperature electrical conductivity was analysed by Mott and Greaves VRH. Several polaron hopping related parameters at high temperature region and density of states at low temperature region were computed. The high temperature DC activation energy measured by conductivity, calculated numerous pertained parameters varied nonlinearly with mole fraction of vanadium content. The Study exhibits DC electrical conduction is due to both alkali and transition metal ions and thus confirms the mixed conductivity. A crossover conduction mechanism from the ionic dominant region to polaronic predominant region has been also observed. Studies revealed the single transition effect at 0.4 mol fraction of V<sub>2</sub>O<sub>5</sub> content.
文摘This article aims to investigate the possibility to turn the multiferroic orders and magnetocapacitance effect close to/above room temperature in nanosized GaFeO3 ceramics by a sol-gel preparation method and substitution with non-magnetic Zn atoms. Therefore, in this work, we have synthesized a series of nanocrystalline Ga1-xZnxFeO3(GZFO, x = 0, 0.01, 0.05 and 0.1) ceramic samples and study the effect of Zn substitution on their structural, magnetic, and electric properties. All the GZFO samples have an orthorhombic structure with Pc21n space group and the value of lattice parameters increase systematically with increasing Zn concentration. Interestingly, it shows that magnetic and electric properties are strongly dependent on the Zn substitution concentration. Based on the results of temperature-dependent magnetizations, M(T), it is observed that with increasing Zn-content up to 0.10, the ferrimagnetic transition temperature (TC) increases from 306 to 320 K. It is also found that the nanocrystalline Zn-doped GaFeO3 (GFO) samples exhibit the characteristics of ferroelectricity at room temperature. Furthermore, the?magnetization, ferroelectric polarization and magnetocapacitance of Zn-doped GFO nanosized ceramics are enhanced compared to those of the pristine sample of GFO ferrite. These results open wide perspectives for the applications of room temperature multiferroic devices.
文摘The reactivity of the recycled glass powder (GP) in a cementitious medium has been studied over time by means of X-ray diffraction and thermal gravimetric analysis. Two different mixtures based on cement/glass powder (0 or 20 wt% GP) and lime/glass powder (70 wt% GP) were considered. Analysis revealed the coexistence of both hydration and pozzolanic reaction during the hardening of the mortars. At young age, the cement hydration would prevail over the pozzolanic one resulting in a decrease of physico-chemical </span></span><a name="_GoBack"></a><span><span><span style="font-family:"">and mechanical properties of the material due to the dilution effect. The pozzolanic reaction that predominates from 91 days, would induce the formation of supplementary C-S-H leading to improve the material properties.
文摘A new type of cerium borate glass-ceramic is prepared and studied. The microstructure and crystallization behaviors of the glass samples were investigated by X-ray diffraction (XRD), electron diffraction (ED), and <sup><span style="font-size:12px;font-family:Verdana;">31</span></sup><span style="font-family:Verdana;">P NMR spectroscopy. The microstructures of samples contain <1 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">are amorphous in nature. More addition of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> transforms the glass to glass-ceramics without thermal annealing. The morphological change of the microstructure of these materials was followed by transmission electron microscopy (TEM). The obtained results have revealed that the addition of more than 0.8 mol% CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> can promote nucleation and crystallization routes that </span></span><span style="font-family:Verdana;">are </span><span style="font-family:;" "=""><span style="font-family:Verdana;">combined with the establishment of diverse crystalline phases. Glasses with lower contents of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">showed no tendency to crystallization. The crystals of CeO</span><sub><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> containing glasses were spheroid like morphology that </span></span><span style="font-family:Verdana;">was </span><span style="font-family:Verdana;">assigned to the three-dimensional fast growth of the well-formed structural species in the boro-apatite phase. In addition, the cerium free glass is characterized by particle-like morphology. Then the growth of spheroid species
文摘The devitrification of glasses with composition 50GeO2-40PbO-10PbF2-xREF3, RE = Gd, Eu, 0 3+: β-PbF2 nanocrystals embedded in a glassy oxide matrix. This transformation is investigated using thermal analysis, X-ray diffraction and electron microscopy. A comparison with RE3+: β-PbF2 ceramics prepared by standard ceramic techniques is performed. The Rare Earth cations show a strong nucleating effect for the precipitation of the RE3++: β-PbF2 nanocrystals. The evolution of the unit cell parameters of the REF3: β-PbF2 solid solution results from a combined effect of Pb2+-RE3+ substitution and interstitial F– introduction. In the glass ceramics, RE3+: β-PbF2 nanocrystals are constrained by the glassy matrix when they form with a pressure equivalent to 1.6 GPa. The constrained nanocrystals can return to a relaxed state by chemical dissolution of the embedding glassy matrix, followed by thermal treatments.
文摘Transparent conducting films of zinc oxide and indium-doped zinc oxide have been prepared by a simple and economical sol-gel technique. This process is feasible for the fabrication of high quality TCO thin films when the processing parameters are optimized. It was found that the out-diffusion of oxygen during the vacuum annealing step was a crucial factor to prepare thin layer with superior properties. Annealing lowers the resistivity down to 4.7 10-3?Ω·cm for the 1 at.% doped films due to the liberation of high-valency In-dopants and the enhanced film density. At high indium concentrations, the free electron density stabilizes because an increasing number of dopant atoms form some kinds of neutral defects. The neutralized indium atoms do not contribute free electrons. The feasibility to deposit highly transparent ZnO thin films has been demonstrated.
文摘The structure of glasses in the system of xCeO2(100?-?x)B2O3, x = 30, 40, 50 mol% CeO2 has been explored for the first time by correlation between data obtained from XRD, FTIR and 11B NMR analyses. NMR spectroscopy andFTIR spectroscopy have confirmed that transformation rate of BO3 to BO4 groups is reduced by CeO2 addition.The concentration of Ce4-O-Ce4 is increased at the expense of both B4-O-Ce4 and B3-O-B4 linkages. Boron atoms are mainly coordinated with Ce4 sites as second neighbors due to increasing CeO4 species with further increase of CeO2 concentration. Increasing B4 fraction is considered due to forming of CeO4 with rate higher than that of BO4 units. The change of chemical shift of 11B nuclei upon exchanging B2O3 with CeO2 confirms that the central boron atoms would be coordinated with tetrahedral cerium atoms as second neighbors. The X-ray diffraction of cerium rich glass is clearly indicated that the formation of crystalline phases refers to CeO4, CeBO3and Ce(BO2)3 species.
文摘In this work the effect of the type of the bonding interlayer (polyvinyl butyral (PVB) or Ethyl Vinyl Acetate (EVA)), number of bonding layers, and the position and the thickness of the Glass plates on the maximum load capacity and absorbed energy by laminated glass. Furthermore, this investigation presents a mathematical model that relates the maximum force capacity of the glass laminated structure to the glass plate thickness, type and thickness of the inter-layer regardless the position of the fixed glass plate. Both practical work results and the theoretical model indicate that the maximum load capacity of laminated glass bonded with either PVB or EVA decreases as the interlayer thickness increases. Moreover, the maximum load capacity for the glasses bonded with EVA is greater than those for the PVB bonded ones under the same conditions. On the other hand, it was observed that that laminated glass absorbed energy increases with the increase of the interlayer thickness and the increase of glass plate thickness.
