Base Glass Research Articles

Release of Gd-ions from peralkaline borosilicate glass in pure water for neutrino detection in Water-Cherenkov Detectors

The addition of Gadolinium (Gd)-based salt, specially GdCl3, in the Water Cherenkov Detectors (WCDs) enhances the sensitivity to neutrino detection. However, the unwanted Cl-based byproducts, significantly reduces the transparency of water and sensitivity of WCDs. An alternative method, to introduce Gd-ions in the WCDs, is through Gd-release from a custom designed Gd-doped glass, when in contact with water. This can potentially eliminate the use of Gd-based salts and byproducts. In this work, we report the Gd-ions release for a Gd-doped peralkaline (Na/Al > 1) borosilicate glass, which closely represents photomultiplier tube (PMT) glass composition used in WCDs. The purpose of the paper is to show that the Gd-ion release from a custom designed glass in the form of beads or powders is feasible and could be used as a controlled Gd-source in future WCDs to enhance neutrino detection. In addition, we present our results of Gd-solubility in the base glass composition.

Evaluation of solubility and cytotoxicity of lanthanum-doped phosphate glasses nanoparticles for drug delivery applications

This paper examined the preparation and characterization of lanthanum-doped phosphate glasses nanoparticles designed for effective management of bone regeneration and associated infections. Glasses incorporated different La2O3 contents (0, 5 and 10mol%) were prepared successfully by a modified alkoxide sol-gel method. They were encoded as P0, PL5 and PL10. Specific surface area and the total pore volume of the glasses were found to decrease by the addition of La2O3. TEM photos showed that glasses were spherical nanoparticles and incorporated uniform mesopores which increased in size by the increase of La2O3 contents. On the other hand, the dissolution of glasses nanoparticles was tested in different media (distilled H2O, SBF and tris-HCl buffer). The results showed that lanthanum-modified glasses demonstrated faster ionic release profiles of phosphate species relative to the base glass with faster dissolution from PL5 relative to PL10 in both distilled H2O and tris-HCl buffer. Furthermore, the possibility of using such glasses as a drug carrier was examined by loading the ciprofloxacin onto samples and studied its release profile. A sustained drug release profile from all phosphate glasses was achieved. Additionally, the incorporation of La2O3 in the modified glasses led to a prolonged drug release pattern relative to the base glass.The cytotoxicity test against BHK fibroblast cells showed that all phosphate nanoparticles were biocompatible. The viability of incubated cells with PL10 was >97% suggesting that PL10 was not toxic up to 2.5mg dose. However, a mild reduction of cell viability (93.3%) occurred at 5mg, and at this dose, the cell viability increased in the following order P0→PL5→PL10, as it was 80, 87.4 and 93.3%.In conclusion, the long-term sustained pattern provided merely by the lanthanum-modified phosphate glasses nanoparticles implied the possibility of their application for localized osteomyelitis treatment.

Influences of powder granularity on crystallizing characteristics in mica-contained glass ceramic

A machinable mica-contained glass ceramic in the SiO2-Al2O3-MgO-F glassy system was prepared by ball milling and hot pressed sintering. Three kinds of powder sizes of base glass were chosen and the effects of the glass powder sizes on the crystallization were explored by x-ray diffraction and scanning electron microscopy techniques. The results indicate that mica crystal as a major phase and KFeSi2O6 and mullite as minor phases are crystallized. Applying pressure at 670°C has little influences on the types of crystal precipitated and the preferential growth of crystal. The powder sizes, however, have obvious effects on the morphology of precipitated mica crystals. In the glass sample with a powder size of d50=16.4 µm, the plate-shaped mica phase is precipitated. As the powder size decrease to 9.9 µm and 3.3 µm, however, the particle-shaped mica is formed instead of the plate-shaped crystals.

Spectroscopic studies of ZnO borate–tellurite glass doped with Eu2O3

Optical, physical and thermal properties of glasses with composition 24B2O3−(25−x) ZnO−51TeO2, x Eu2O3, mol% (where x=0.0, 0.5, 1 and 3%) were studied. The density, crystallization temperature, oxygen packing density and glassy temperature were found to increase with the addition of Eu2O3. The molar volume, optical band gap (Eg) and refractive index values were found to decrease with increasing Eu2O3 content. The FTIR measurements indicated that the continuous increase of europium concentration helped conversion of [BO3] to [BO4] groups in the base glass ZnO TeO2–B2O3. Thermal analysis reveals that the glass transition temperature Tg, the glass thermal stability ΔT and the glass forming ability Kg increased by the addition of Eu2O3. The transmission and absorption spectra of all glasses indicated that there is a decrease in the optical band gap Eg values due to the enhancement of the number of non-bridging oxygen (NBO) atoms with the addition of Eu2O3. The studied glasses have high values of nonlinear refractive index n2 and nonlinear optical susceptibility χ(3) with a good thermal stability. Thus, such glasses have promised applications in nonlinear optical devices.

Sputter coated ZnO thin films on glass and polycarbonate: Evaluation of stability and interaction with Flavin adenine dinucleotide-dependent oxidases.

Aqueous stability of sputter coated ZnO thin films were studied on two base materials, viz., polycarbonate (PC) and glass. The films showed higher stability on PC compared to glass, when exposed to aqueous buffered solution at pH-7.4, as studied by x-ray diffraction, surface reflectometry, and inductively coupled plasma-optical emission spectroscopy. Glucose oxidase (GOx) and cholesterol oxidase (Chl.Ox.) were used as model enzymes to study their electrochemical interaction with ZnO/PC. GOx showed a higher immobilization on ZnO/PC with an activity of 9.2 ± 1.7 mU cm-2 compared to Chl.Ox. with an activity of 2.79 ± 0.5 mU cm-2. This is attributed to the larger crystallite size and higher Zn per unit area on PC as compared to glass which enabled a higher activity of GOx on ZnO/PC compared to ZnO/glass. Immobilization was mainly dependent on the surface residue and the charge of the enzyme as indicated by zeta potential which showed -23 mV for GOx compared to -6 mV for Chl.Ox. under physiological conditions. Further under unstirred condition, the reaction was limited by diffusion of the substrate for the enzyme. Chl.Ox. showed a lower activity as compared to GOx on the surface due to low diffusional coefficient of the bulky cholesterol molecule as compared to glucose. It was confirmed by low charge transfer resistance in electrochemical impedance spectroscopy for GOx (1.51 ± 0.072 × 105 Ω) as compared to Chl.Ox. (1.98 ± 0.09 × 105 Ω). But under stirring condition, the diffusion limitation was overcome, and the sensitivity for Chl.Ox./ZnO was 11.2 μA cm-2 mM-1 as compared to GOx/ZnO/PC with 3.5 μA cm-2 mM-1. Thus, sputter coated ZnO thin films appeared to be good quality transducers for immobilization of oxidases with sensitivity dependent on the substrate diffusion and its potential application in biosensors.

Crystallization features and physico-chemical properties of alkali and alkaline aluminoborate glass–ceramics

Preparation and characterization of glass–ceramics based on CaO–Al2O3–B2O3 system, modified by replacing CaO by different alkali and alkaline earth oxides, and In2O3/Al2O3 substitustion were implemented. Different crystalline phases, including β-CaAl2B2O7, Na2Al2B2O7, LiAl5O8, Li4Al4B6O17, Li2AlBO4, SrAl2B2O7, BaAl2B2O7, α-(Ca1-x,Inx)Al2B2O7, and InBO3, were developed from the heat-treated glasses. The incorporation of In3+ in the position of Ca2+ in β-CaAl2B2O7 crystal lattice was responsible for phase transition of β-CaAl2B2O7 to α-CaAl2B2O7 phase. The coefficient of thermal expansion CTE of prepared glass–ceramics was between −65 × 10−7 and 72 × 10−7 K−1 in the temperature range from 25 to 600 °C. The glass–ceramic specimens containing XAl2B2O7 as the principal crystalline phase were characterized by negative CTE values. In contrast, the replacement of CaO in the base glass by alkali oxides like Na2O and Li2O led to a dramatic transformation of the negative CTE to postive values. The complete replacement of calcium oxide in the base glass by various alkali and alkaline earth oxides markedly decreased the chemical durability of the investigated glass–ceramic specimens, while substitution of Al2O3 by In2O3 resulted in improving the chemical stability of the crystalline samples. The density of the glass specimens were found to be within the range 2.35–3.38 g/cm3, while the density of the glass–ceramic samples was in the range of 2.37–3.13 g/cm3.

The influence of ZnO incorporation on the aqueous leaching characteristics of a borosilicate glass

With increasing ZnO content, short term aqueous durability enhancement of all elements in borosilicate glasses containing 1.0 and 3.85 wt% ZnO was evident in 7-day PCT-B tests. In 14-day MCC-1 type leach tests conducted at 90 °C, surface alteration was very clear in the undoped glass via the formation of strongly altered amorphous material which tended to spall off the surface. No sign of crystallinity was detected by grazing incidence X-ray diffraction or electron microscopy of the surface layers and the surface material was very rich in silica. For the ZnO-bearing glasses, significant growth of particles following PCT leaching for 7 days was observed, due to a build-up of surface ZnO-containing Si-rich material and possible agglomeration. This alteration layer was also observed in MCC-1 type experiments in which cross-section SEM-EDS data were obtained. Raman, infrared and 11B and 29Si MAS NMR spectroscopy showed only slight changes in boron speciation on the addition of up to 9.1 wt% ZnO. Bulk positron annihilation lifetime spectra (PALS) of glasses containing 0–3.85 wt% ZnO could be analysed with three distinct lifetimes and also showed only slight differences. These results indicate that the basic glass structure was essentially not influenced by the ZnO content and that the passivation of the alteration layer is promoted by ZnO content.

Optical, FTIR and ESR Spectral Investigations of Tungsten Ions in Barium Phosphate Host Glass and Effects of Gamma Irradiation

Tungsten oxide (0.25 – 3% WO3) doped barium phosphate glasses were prepared by the conventional melting annealing procedure. Spectroscopic FTIR infrared and ESR measurements were applied at 0 and 10 Mrad doses of gamma irradiations. The UV-Visible spectrum of the base glass consists of distinct ultraviolet peaks that can be correlated with trace ferric (Fe3+ ions) impurities. UV-Visible absorption spectra of WO3 – doped glasses show similar ultraviolet absorption as the base glass and a very broad visible band settled at about 720 nm and with the high content sample (3% WO3) two peaks are identified at 602 and 790 nm on the very broad visible absorption band. These additional broad band accompanied by the bluish color to the samples support the assumption of the formation or presence of pentavalent tungsten ions because of the reducing nature of the phosphate host glass. Gamma irradiation produces some extension of the UV absorption of the undoped glass spectrum accompanied by the generation of an induced visible broad band centered at 520 nm. These extra induced changes are related to some photochemical reactions leading to the partial oxidation of some ferrous ions to ferric ions through the radiation effect. The induced broad visible band is assumed to be related to the formation of phosphorus oxygen hole centers (POHC) or nonbridging oxygen hole centers (NBOHC) from interaction of gamma rays on the phosphate network. Gamma irradiation of WO3 doped glasses reveals the increase of the intensity of the very broad band and in the high content sample (3% WO3), a new induced band is generated at about 411 nm. These changes are assumed to be related to some photochemical reactions involving the conversion of some W6+ ions to W5+ ions by capturing electrons or by photo-reduction of W6+ ions to W4+ ions and thus imparting the additional peak at 411 nm. FTIR results of the studied glasses reveal the appearance of vibrational modes due to phosphate network groups mainly of metaphosphate units or P–O–P linkages as the response of the chemical composition 50% BaO – 50% P2O5. The infrared results of the radiative samples have no notable changes due to compactness of the phosphate with noticeable amount of heavy Ba2+ ions which seem to retard the passage of liberated electrons or positive holes during the irradiation process and thus the network structure remains unaffected. ESR spectra of WO3 – doped glasses reveal distinct signals due to the unpaired pentavalent ions which are stable towards irradiation due to the existence of a high content of the heavy Ba2+ ions which block the passage of negative and positive holes during irradiation.

The environment of Fe3+/Fe2+ cations in a sodium borosilicate glass

The neutron diffraction isotopic substitution technique is employed to investigate the environment of Fe3+/Fe2+ cations in a sodium borosilicate glass matrix of composition 0.210Na2O0.18511B2O30.605SiO2. The neutron diffraction data were obtained using the D4c diffractometer at the Institut Laue-Langevin (ILL; Grenoble, France), and were recorded for three samples; the base glass, the base glass incorporating natural Fe2O3 (12 mol.%) and a similar glass containing Fe2O3 enriched in 57Fe. The data are Fourier transformed to yield the real-space total correlation function, T(r), and the first co-ordination shells of the Fe3+/Fe2+ cations are investigated via a peak fit to the isotopic difference correlation function TFe(r). It is concluded that the iron is mainly present as Fe3+ cations, both tetrahedrally and octahedrally co-ordinated by oxygen atoms, plus a small fraction (0.07 ± 0.01) of Fe2+ cations in octahedral co-ordination. The Fe3+ tetrahedral fraction is 0.45 ± 0.10, and appears to exist as FeO4 structural units incorporated into the network of silicate chemical groupings, with their negative charge being balanced by Na+ network-modifying cations. The remaining Fe3+ cations (fraction 0.48 ± 0.10) are thought to be predominantly octahedrally co-ordinated and associatedwith BO33 orthoborate anions in FeBO3 chemical groupings, which become non-stoichiometric due to the reduction of some of the Fe3+ cations to Fe2+.

Nondestructive Redox Quantification Reveals Glassmaking of Rare French Gothic Stained Glasses

The sophisticated colors of medieval glasses arise from their transition metal (TM) impurities and capture information about ancient glassmaking techniques. Beyond the glass chemical composition, the TM redox is also a key factor in the glass color, but its quantification without any sampling is a challenge. We report a combination of nondestructive and noninvasive quantitative analyses of the chemical composition by particle-induced X-ray emission–particle-induced γ-ray emission mappings and of the color and TM element speciation by optical absorption spectroscopy performed on a red-blue-purple striped glass from the stained glass windows of the Sainte-Chapelle in Paris, France, during its restoration. These particular glass pieces must have been produced as a single shot, which guarantees that the chemical variations reflect the recipe in use in a specific medieval workshop. The quantitative elemental mappings demonstrate that the colored glass parts are derived from the same base glass, to which TMs were deliberately added. Optical absorption spectra reveal the origin of the colors: blue from CoII, red from copper nanoparticles, and purple from MnIII. Furthermore, the derivation of the quantitative redox state of each TM in each color shows that the contents of Fe, Cu, and Mn were adjusted to ensure a reducing glass matrix in the red stripe or a metastable overoxidized glass in the purple stripe. We infer that the agility of the medieval glassmaker allowed him to master the redox kinetics in the glass by rapid shaping and cooling to obtain a snapshot of the thermodynamically unstable glass colors.

Low melting glasses in ZnO-Fe2O3-P2O5 system with high chemical durability and thermal stability for sealing or waste immobilization

Structure, chemical durability and thermal properties of two glass series (A and B) in ZnO-Fe2O3-P2O5 system were investigated in this study. Nominal compositions of A and B glass series are (100−x)[0.45ZnO-0.1Fe2O3-0.45P2O5]-xAO (in mol%, x=5, 10, AO=Al2O3, B2O3, SiO2) and (42.75−y)ZnO-9.5Fe2O3-42.75P2O5-5Al2O3-yBO (in mol%, y=5, 10, BO=Bi2O3, MoO3), respectively. For glasses in A series, the variations in thermal expansion coefficient and characterization temperature are slight with theses oxides addition; thermal stability improved with the addition of SiO2; chemical durability improved with the addition of B2O3 or Al2O3; A2 glass obtained by 5mol% Al2O3 addition has good comprehensive performance in A series, and it was chosen as base glass in B series. High thermal stability (TS=201°C), high chemical durability (DR=3.2×10−8g/cm2/min), relative low thermal expansion coefficient (α25–300°C=7.71×10−6/°C) are achieved simultaneously in B2 glass prepared by the substitution of 5mol% Bi2O3 for ZnO in A2 glass. A2, A4, A5 and B2 glasses have potential to be used in 490–600°C sealing applications. B2 glass also has the potential to be used in high level radioactive waste immobilization.

Considering the effects of the Byzantine–Islamic transition: Umayyad glass tesserae and vessels from the qasr of Khirbet al-Mafjar (Jericho, Palestine)

The paper reports and discusses data obtained by archaeological and archaeometric studies of glass vessels and tesserae from the qasr of Khirbet al-Mafjar (near Jericho, Palestine). Archaeological contextualisation of the site and chrono-typological study of glass vessels were associated to EPMA and LA–ICP–MS analyses, performed to characterise the composition of the glassy matrix (major and minor components as well as trace elements). Analyses allowed achieving meaningful and intriguing results, which gain insights into the production and consumption of glass vessels and tesserae in the near East during the Umayyad period (seventh–eighth centuries). Within the analysed samples, both an Egyptian and a Levantine manufacture have been identified: such data provide evidence of a double supply of glass from Egypt and the Syro-Palestinian coast in the Umayyad period occurring not only in the glassware manufacture but also in the production of base glass intended to be used in the manufacture of mosaic tesserae. Thus, the achieved results represent the first material evidence of a non-exclusive gathering of glass tesserae from Byzantium and the Byzantines in the manufacture of early Islamic mosaics.

FABRICATION AND CHARACTERIZATION STUDIES OF LITHIUM-BORATE RUBY GLASSES CONTAINING GOLD NANOPARTICLES

Glasses containing Au nanoparticles have been synthesized in the base glass of composition 30Li2O–70B2O3 using gold chloride (HAuCl4.3H2O) as a dopant. The characteristic ruby color has been observed which is attributed due to surface plasmon resonance of the Au nanoparticles. The hue of the color increases with the increase of concentration of the dopant. Presence of the gold nanoparticles has been confirmed by studying the optical absorption spectra in the visible range which show a characteristic absorption peak at ~560nm. XRD and SEM studies show that the addition of Au increases the kinetics of growth and crystallization. ESR studies indicate that the electronic state of gold is either Au0 or Au+.

Effect of ZrO2 on the bioactivity properties of gel-derived CaO-P2O5-SiO2-SrO glasses

Abstract Zr-incorporated CaO-P 2 O 5 -SiO 2 -SrO-ZrO 2 (BG-Zr) bioactive glasses were prepared through the sol-gel process by adding zirconium oxychloride to the synthesis batch as the zirconia precursor. The added amount of ZrO 2 was 5, 8 and 11 wt%, respectively, to replace the same amount of CaO. The effect of ZrO 2 on the solubility, bioactivity and structural properties of BG-Zr were investigated. The differential thermal analysis (TG/DTA) and X-ray diffraction (XRD) indicated that the addition of ZrO 2 to the base glass composition increased its crystallization temperature as well as weakened its crystallization tendency. Zr 4+ ion substituted for Ca 2+ favors covalent O-Zr-O bonding formation, making the glass network stronger, and thus BG-Zr glasses exhibit enhanced bending strength. Immersion tests in hydroxymethylaminomethane (Tris) buffer and simulated body fluid (SBF) show BG-Zr glasses to exhibit slower dissolution rate and lower rate of apatite formation with increasing ZrO 2 content compared to the base glass, which is likely associated with their structure stabilization and lower solubility.

Crystallization characteristics and physico-chemical properties of glass–ceramics based on Li2O–ZnO–SiO2 system

Glass materials based on lithium zinc silicate system of the composition 24Li2O–20ZnO–56SiO2 LZS (mol%) were prepared and converted to glass–ceramics using controlled heat-treatment schedules. The LZS base glass system was modified by addition of Al2O3 and MO/ZnO replacements where MO=CaO, CdO and SrO oxides. Several crystalline phases were developed, including lithium zinc orthosilicate, α-quartz, β-spodumene solid solution, lithium meta and disilicate, Ca-wollastonite, Cd or Sr metasilicate, and Sr-zinc silicate of hardystonite type. The effects of crystallization process on some properties, like thermal expansion coefficient (TEC), chemical stability, and density of glass–ceramics were evaluated. The TEC of crystalline samples varied from 72×10−7 to 149×10−7K−1, 25–600 and density values in the range, 2.67–3.29g/cm3. The addition of Al2O3 and MO/ZnO replacements in the base glass led to improve the chemical durability of the glass–ceramics samples. As a result of the thermal and physico-chemical properties of the studied glass–ceramic, the materials acquire excellent properties and can be used to seal a variety of different metals and alloys.

The influence of CdSe and ZnSe nanoparticles on the optical properties of Sm3+ ions in lead borate glasses

The effect of glass composition and the presence of CdSe/ZnSe nanoparticles (NPs) on the optical absorption and fluorescence of Sm-doped lead borate glasses are studied. Three sets of glass samples xPbO:(99.5-x) B2O3:0.5Sm2O3, x = 29.5–69.5 mol%, xPbO:(96.5-x) B2O3:0.5Sm2O3: 3CdSe/ZnSe, x = 36.5, and 56.5 mol% are prepared. NPs are grown by annealing these glasses just below the glass transition temperature. Average size of both types of NPs increases with annealing time; however, CdSe NPs grew to a larger size range (2 to 20 nm) compared to ZnSe NPs (1 to 16 nm). We analyzed the hypersensitive transition, intensity parameters, radiative transition probability, stimulated emission cross section (σp), and the area ratio of the electric dipole/magnetic dipole transitions of Sm3+. The intensity parameters show a minimum at 11 h annealing for 36.5 mol% and a maximum for the same annealing duration in 56.5 mol% PbO containing CdSe NPs. The σp for 56.5 mol% of PbO with CdSe NPs is found to be a maximum when the average NP size is around 14 nm. ZnSe NPs containing glasses also show significant changes in σp when the average particle size is ~16 nm, for 36.5 mol% PbO. Our results suggest that the optical properties of Sm3+ in lead borate glasses are sensitive to its electronic environment which can be modified by varying the base glass composition and/or incorporating large NPs of CdSe/ZnSe. The large σp values that we observe for some of the glass compositions make them attractive materials for photonic devices and photovoltaic applications.

Analyses of glass tesserae from Kilise Tepe: New insights into an early Byzantine production technology

There is substantial archaeological evidence to suggest that glass mosaics were ubiquitous throughout late antique and Byzantine Asia Minor. However, issues about the manufacture of Byzantine glass tesserae, the diffusion of their technology and the economic implications have been little discussed. This paper presents the results of the analytical and technological investigation of 28 glass fragments from Kilise Tepe (Cilicia, Turkey), including 22 tesserae, 3 gilded plaques and 1 fragment of a window, a vessel and an ingot. The samples were analysed by EPMA, LA-ICP-MS and SEM-EDS. Two different base glasses from different primary production sites were used in the production of the glass: Foy-2 probably from Egypt, and Levantine I produced in Syro-Palestine. Variations in the chemical fingerprint and morphology of crystalline particles reveal differences in the colouring and opacifying techniques that may point to multiple secondary production sites. Whereas the red samples show signs of in situ crystallization of metallic copper, ready-made lead stannate was added as yellow pigment for the colouring of the green and yellow tesserae. In addition, calcium phosphate particles, likely deriving from bone-ash, were found in one turquoise specimen. When compared with other late antique sites, our results testify to changes in the Roman centralized production tradition and a diversification of supply and secondary manufacturing practices of mosaic tesserae.

Apatite Glass-Ceramics: A Review

This article is a review of the published literature on apatite glass-ceramics (GCs). Topics covered include crystallization mechanisms of the various families of the apatite GCs and an update on research and development on apatite GCs for applications in orthopedics, dentistry, optoelectronics and nuclear waste management. Most apatite GCs crystallize through a homogenous nucleation and crystallization mechanism, which is aided by a prior liquid-liquid phase separation. Careful control of the base glass composition and heat-treatment conditions, which determine the nature and morphology of the crystal phases in the GC can produce GC materials with exceptional thermal, mechanical, optical and biological properties. The GCs reviewed for orthopedic applications exhibit suitable mechanical properties and can chemically bond to bone and stimulate its regeneration. The most commercially successful apatite GCs are those developed for dental veneering. These materials exhibit excellent translucency and clinical esthetics, and mimic the natural tooth mineral. Due to the ease of solid solution of the apatite lattice, rare earth doped apatite GCs are discussed for potential applications in optoelectronics and nuclear waste management. One of the drawbacks of the commercial apatite GCs used in orthopedics is the lack of resorbability, therefore the review provides a direction for future research in the field.

High‐temperature calorimetric study of oxide component dissolution in a CaO–MgO–Al2O3–SiO2 slag at 1450°C

AbstractBlast‐furnace slags are formed, as iron ore is reduced to metal, as a molten a mixture of refractory and not easily reducible oxides, largely silica, alumina, lime, and magnesia. Their relatively low silica content makes them basic and poor glass formers. Their thermodynamic properties, though important for modeling their formation and reactivity, as well as furnace heat balance, are poorly known. Solution calorimetry of small amounts of solid oxides in a molten oxide solvent at high temperature (up to about 1500°C) permits direct assessment of energetics of dissolution. The enthalpies of solution of slag forming oxides: CaO, SiO2, Al2O3, MgO, and Fe2O3 in a simplified model slag of composition: CaO (45.9 mol%), SiO2 (35.1 mol%), Al2O3 (8.3 mol%), MgO (10.7 mol%) were measured by high‐temperature drop solution calorimetry at 1450°C. For this slag composition, enthalpies of solution become more exothermic in the order: Fe2O3 (279.3 ± 20.8 kJ/mol), MgO (56.7 ± 9.1 kJ/mol), Al2O, (41.6 ± 11.3 kJ/mol), CaO (−4.3 ± 2.3 kJ/mol), and SiO2, (−20.4 ± 4.4 kJ/mol), reflecting the relatively basic character of this low‐silica melt. Within these fairly large experimental errors, characteristic of calorimetry at this high temperature, there is little or no discernible concentration dependence for these heats of solution. The trends seen for these five solutes parallel those seen for heats of solution of the same oxides in other melts at various temperatures, with changes in magnitude reflecting the differences in acid‐base character of the melts. The new data for quartz show systematic behavior which extends the range of basicity studied for the enthalpy of dissolution of silica. The results provide reliable data for future modeling of the thermal balance of steel‐making furnaces and geologic and ceramic systems.

Effects of Fe2O3 content on ionic conductivity of Li2O-TiO2-P2O5 glasses and glass-ceramics

In this study, Li2O-TiO2-P2O5-x(Fe2O3) (x = 0, 2.5, 5 and 7.5 weight part) glass and glass-ceramics were synthesized through conventional melt-quenching method and subsequently heat treatment. Glass samples were studied by UV–visible spectroscopy and crystallized samples were characterized by differential thermal analysis, X-ray diffractometry and field emission scanning electron microscopy. Besides, electrical properties were examined according to the electrochemical impedance spectroscopy techniques.Experimental optical spectra of the Fe2O3-doped glasses revealed strong UV absorption band in the range of 330–370 nm, which were attributed to the presence of Fe3+ ions. The major crystalline phase of the fabricated glass-ceramics was LiTi2(PO4)3. However, Li3PO4 was also identified as the minor one. Considering the impedance spectroscopy studies, ionic conductivity of Fe2O3 containing glasses was higher than that of the base glass. Additionally, the maximum bulk ionic conductivity of 1.38 × 10−3 S/cm was achieved as well as activation energy as low as 0.26 eV at room temperature for x = 5.