Sintering behavior,structure and dielectric properties of CuO-ZnO-MgO-B2O3 glass-ceramics for ULTCC applications

High performance ultra-low temperature co-fired ceramic (ULTCC) materials were prepared from CuO- MgO- ZnO- Al₂O₃- B₂O₃- Li₂O glass-ceramics. The sintering behaviors, crystalline phase evolution, microstructure and dielectric properties, as well as their compatibility with Ag and Al electrodes, were investigated. With the suitable substitution of MgO for ZnO, the dielectric properties of glass-ceramics were improved. It is mainly associated with the fine microstructure, highly crystallinity, and decrease in tetrahedral distortion in the crystal lattice. All the glasses completed the densification at 575–600 °C, and ZnB₄O₇ is the only crystalline phase precipitated from the glasses. Moreover, the glass-ceramic with 1 wt% MgO sintered at 575 °C for 5 h, exhibited low relative permittivity ~ 7.1 and low dielectric loss ~ 6.40 × 10^?4. And the glass-ceramic with 4 wt% MgO sintered at 600 °C for 5 h, also displayed low relative permittivity ~ 7.1 and low dielectric loss ~ 5.77 × 10^?4. Both two glasses have good sintering compatibility with silver and aluminum electrodes, which provided high potential for ULTCC application.     

Influence of Al2O3/SiO2 ratio in multicomponent LNAS glasses and glass-ceramics on the crystallization behavior,microstructure and mechanical performance

Transparent glass-ceramics containing eucryptite and nepheline crystalline phases were prepared from alkali (Li, Na) aluminosilicate glasses with various mole substitutions of Al₂O₃ for SiO₂. The relationships between glass network structure and crystallization behavior of Li₂O–Na₂O–Al₂O₃–SiO₂ (LNAS) glasses were investigated. It was found that the crystallization of the eucryptite and nepheline in LNAS glasses significantly depended on the concentration of Al₂O₃. LNAS glasses with the addition of Al₂O₃ from 16 to 18 mol% exhibited increasing Q⁴ (mAl) structural units confirmed by NMR and Raman spectroscopy, which promoted the formation of eucryptite and nepheline crystalline phases. With the Al₂O₃ content increasing to 19–20 mol%, the formation of highly disordered (Li, Na)₃PO₄ phase which can serve as nucleation sites was inhibited and the crystallization mechanism of glass became surface crystallization. Glass-ceramics containing 18 mol% Al₂O₃ showed high transparency ～84% at 550 nm. Moreover, the microhardness, elastic modulus and fracture toughness are 8.56 GPa, 95.7 GPa and 0.78 MPa m^1/2 respectively. The transparent glass-ceramics with good mechanical properties show high potential in the applications of protective cover of displays.     

New calcium‐free Na2O–Al2O3–P2O5 bioactive glasses with potential applications in bone tissue engineering

Sodium aluminophosphate glasses were evaluated for their bone repair ability. The glasses belonging to the system 45Na₂O–xAl₂O₃‐(55‐x)P₂O₅, with x = (3, 5, 7, 10 mol%) were prepared by a melt‐quenching method. We assessed the effect of Al₂O₃ content on the properties of Na₂O–Al₂O₃–P₂O₅ (NAP) glasses, which were characterized by density measurements, DSC analyses, solubility, bioactivity in simulated body fluid and cytocompatibility with MG‐63 cells. To the best of our knowledge, this is the first investigation of calcium‐free Na₂O–Al₂O₃–P₂O₅ system glasses as bioactive materials for bone tissue engineering.     

Synthesis and characterization of newly developed phosphate-based glasses through experimental gamma-ray and neutron spectroscopy methods: Transmission and dose rates

In this study, four new phosphate-based glasses with the compositions of CaO–Na₂O–K₂O–P₂O₅ (PN system), CaO–Na₂O–K₂O–Al₂O₃–P₂O₅ (PA system) and CaO–Na₂O–K₂O–Al₂O₃–SiO₂–P₂O₅ (PS system) were synthesized and characterized through experimental gamma-ray and neutron spectroscopy methods. Glass densities were then measured experimentally and evaluated theoretically. Next, a high purity Germanium (HPGe) detector was used for determining the fundamental gamma-ray transmission parameters in 35.4–383 keV gamma-ray energies emitted from ¹³³Ba source (Radioactivity: 3Ci). Additionally, the experimental setup was used to determine the equivalent dose (EAD) to get a better knowledge of fast neutron attenuation. Our findings indicate that experimental gamma-ray transmission measurements are consistent with standard theoretical data (EpiXS). Consequently, PA10 was shown to have higher gamma-ray and neutron attenuation capabilities when compared to the other glass samples studied. Our outcomes showed that increasing the molar contribution of Al₂O₃ to the phosphate-based glasses increased not only their transparency but also their gamma-ray and neutron attenuation capacities. It can be concluded that substituting Al₂O₃ for P₂O₅ is a functional and monotonic tool for improving the optical, gamma-ray, and neutron attenuation of phosphate-based glasses, which are being evaluated as prospective shielding materials for medical and industrial radiation facilities.     

Enhancement of luminescence properties and the role of ZnO in Tb3+ ions doped zinc aluminum phosphate glasses

Terbium ion doped zinc aluminum phosphate (ZAP) glasses with composition (90−x)((90−y)P₂O₅–10Al₂O₃–yZnO)–xTb₂O₃ (x=0.5–9 in mol% and y=30, 35, 40 in mol%) have been prepared by melt quenching method, and the effects of the Tb₂O₃ and ZnO content on the luminescence properties have been studied by photoluminescence spectroscopies. It was found that the green emission peaked at 544 nm is significantly enhanced under higher Tb₂O₃ content, meanwhile the sensitization effect of ZnO content is confirmed from the enhanced main emission. The quenching effect attributed to the resonant energy transfer through the cross-relaxation mechanism is observed when Tb₂O₃ concentration is beyond 2.5 mol% due to the fact that more Tb³⁺ ions enhance the 4f→5d and 4f→4f electronic transitions through the dipole–dipole (d–d) interaction. Also, ZnO plays a role of the disperser to prevent non-radiative de-excitation process. A characteristic luminescence image of the (100−x)(60P₂O₅–10Al₂O₃–30ZnO)·xTb₂O₃ series glasses under UV excitation at 366 nm is presented for the first time, and the transition of luminescence suggests that the Tb³⁺-doped ZAP glasses are suitable for green and dual-color blue/green LED applications by modulation of Tb and ZnO composition.     

Radiation attenuation properties of bioactive glasses doped with NiO

This paper focuses on the evaluation of the radiation attenuation properties of 15CaF₂-10CaO-5B₂O₃-(65-x)P₂O₅-xNiO-5BaO (where 0 ≤ x ≤ 1.0 mol%) bioactive glasses. The radiation attenuation features of these glasses were investigated by determining different factors including mass attenuation coefficient (μ/ρ), exposure and absorption buildup factors (EBF and EABF), neutron removal cross section (NRCS), and effective atomic number (Z_eff) for photon, proton, and carbon ion interactions. Geant4 toolkit and Phy-X program were employed for simulations and calculations procedures. The results revealed that NiO content in the studied bioactive glasses has a significant effect on photon interaction and an insignificant effect on the charged particle interactions. The Z_eff values of the studied glasses were observed in the range of 18–20 for photon interaction, 10.7–10.9 for proton interaction, and 10.0–10.7 for carbon ion interaction. The NRCS values were 0.087, 0.088, 0.089, 0.090, and 0.091 cm^-1 for x = 0, 0.4, 0.6, 0.8 and 1.0 mol%, respectively. The studied bioactive glasses showed a good ability to attenuate gamma radiation at energies of medical applications.     

Synthesis,physical, optical,structural and radiation shielding characterization of borate glasses: A focus on the role of SrO/Al2O3 substitution

In a bid to expand the amount of information available on glass systems and their potential applications for radiation shielding design, glass samples with the compositions (30-x)SrO-xAl₂O₃–68B₂O₃–2V₂O₅(x = 5, 7.5, 10, 12.5&15 mol %) coded as SABV0 - 4 were prepared by the melt-quenching technique and analyzed for their optical, structural, physical, and radiation shielding features. The glassy (amorphous) nature of the SABV glass samples was affirmed by broad peaks of X-ray diffraction spectra. Calculated values of density and molar volume shown opposite behavior and the variation of these values were discussed as structural modifications in the glass matrix. From recorded optical absorption spectra optical band gap energy (Eg)-indirect transition, Urbach energy and optical basicity were estimated. FTIR spectra were recorded for all the samples in the range 400 cm^?1 to 4000 cm^?1. The FTIR absorbance spectra unveiled the SABV network structure mainly incorporating of BO₃ and BO₄ units. Raman spectroscopy is achieved to detect the structural changes and at higher wavenumber, B–O stretching modes in [BO₃] observed with one or two NBO's. The results of ESR spectra of glasses have indicated the highly covalent environment of vanadium ions. Analysis of the photon shielding parameters of the glasses which were obtained primarily from FLUKA Monte Carlo simulations and XCOM computations revealed photon energy and glass chemical composition dependence. The mass attenuation coefficient and effective atomic number ranged from 0.2668 to 0.3385 cm²g^-1 and 12.98–15.93 accordingly as the weight fraction of Sr increased from 16.06 to 26.72% in the glasses. Generally, photon shielding ability of the SABV glasses follows the trend: SABV0 > SABV1 > SABV2 > SABV3 > SABV4. The thermal neutron total cross section follows the same trend with values fluctuating between 71.9553 and 80.6268 cm^?1. However, SABV1 showed superior fast neutron moderating capacity among the glasses. The present SABV glasses showed outstanding photon shielding ability compared to common shields. The prepared glasses are thus suitable candidates for radiation protection applications.     

The role of PbO/Bi2O3 insertion on the shielding characteristics of novel borate glasses

Impacts of lead and bismuth oxides insertion on a novel glass system of P₂O₅, B₂O₃, Li₂O, Al₂O₃ according the formula 25B₂O₃–25P₂O₅–10Li₂O–5Al₂O₃–5ZnO-xPbO+ (30-x)Bi₂O₃, x = 5,10, 15, 20, 25 mol%. The mass attenuation coefficient (μ_m = μ/ρ) simulated between 0.015 and 15 MeV using MCNP and calculated theoretically using Phy-X/PSD program. Based on the simulated μ_m, other significant parameters such as linear attenuation coefficient (LAC), half and tenth value layer (HVL, TVL), mean free path (MFP), and effective atomic number (Z_eff) were calculated for fabricated glasses. The G-P fitting methods were used to calculate the exposure and energy absorption buildup factors (EBF and EABF) for fabricated glasses. Furthermore, fast neutron removal cross sections (Σ_R) were calculated theoretically for fabricated glasses. The prepared glasses were effective shielding material which can reduce fast neutrons as well as gamma rays.     

Fabrication of reduced Graphene Oxide supported Gd3+ doped V2O5 nanorod arrays for superior photocatalytic and antibacterial activities

In the current report, pure V₂O₅, a series of Gd doped V₂O₅ (1 wt%, 3 wt%, 5 wt% and 10 wt%) and graphene integrated Gd–V₂O₅ photocatalysts have been prepared using a facile wet chemical approach. The effect of Gd⁺³ ions substitution and RGO support on V₂O₅ was studied by the different analytical techniques. X-ray diffraction (XRD) results showed the orthorhombic crystal structure of synthesized samples with crystallize size in range of 22–35 nm. Morphological analysis showed nanorods and nanorod arrays like appearance of V₂O₅, Gd–V₂O₅ and GdV-₂O₅/RGO, respectively. Gd–V₂O₅ and Gd–V₂O₅/RGO exhibited enhanced optical response in the visible region along with decrease in the band gap values for Gd doped V₂O₅ samples. BET surface area of Gd–V₂O₅ and Gd- V₂O₅/RGO was calculated as 12.39 g/m² and 15.35 g/m² that was found to be higher than pristine V₂O₅. To study the photocatalytic activity of synthesized photocatalysts, methylene blue (MB) was chosen as model pollutant. Among the Gd doped V₂O₅ samples, highest photocatalytic activity (45.62%) was achieved by optimal concentration of 5 wt% Gd–V₂O₅ that is accredited to effective separation of electron-hole pairs. While Gd–V₂O₅/RGO showed 2.1 times higher dye removal (97.12%) than unsupported Gd–V₂O₅, under the visible light irradiation. The significantly high photocatalytic activity of Gd–V₂O₅/RGO is due to the synergistic effect aroused by combined action of Gd⁺³ ions doping and advantageous properties of highly conductive and large surfaced graphene. Recycling experiments for V₂O₅ derivatives showed good stability and recyclability of photocatalysts. Additionally, Gd–V₂O₅/RGO was found to be more potential anti-bacterial agent than V₂O₅ and Gd–V₂O₅.     

Promising electrode material of Fe3O4 nanoparticles decorated on V2O5 nanobelts for high-performance symmetric supercapacitors

Bundled V₂O₅ nanobelts decorated with Fe₃O₄ nanoparticles (F3V nanostructures) were successfully synthesized to develop a low-cost electrode material for energy storage applications. The synthesized samples were subjected to structural, morphological and electrochemical studies. The Fe₃O₄ nanoparticles decorated over bundled V₂O₅ nanobelts exhibited better electrochemical properties than the pristine Fe₃O₄ nanoparticles and V₂O₅ nanobelts. The electrochemical behavior of the fabricated electrodes was investigated in an electrolyte of 3 M KOH, demonstrated an exceptional specific capacity values of 750.1, 660.3, and 1519 F g^–1 for V₂O₅, Fe₃O₄, and F3V respectively at a current density of 15 A g^–1. The assembled F3V symmetric supercapacitor (SSC) device exhibited an excellent specific capacitance of 93 F g^–1 at a current density of 0.5 A g^–1, delivering energy and power densities of 13 Wh.kg^–1 and 1530 W kg^–1, respectively, and superior long-term cycling stability of ～84% capacity retention over 5000 galvanostatic charge–discharge cycles. These findings demonstrate the extraordinary electrochemical characteristics of the F3V nanostructures, indicating their potential use in energy storage applications.     

Melt-quenched oxide glasses with ultrahigh Young's modulus and small thermal expansion coefficient

The well-known Makishima–Mackenzie relationship, consisting of two terms of the dense packing structure and dissociation energy regarding bonding in constituent oxides, enables fabricating oxide glasses with ultrahigh Young's modulus (∼140 GPa) and a small coefficient of thermal expansion (CTE) (∼4 ppm/K). The effects of increasing MgO and Ta₂O₅ contents in an MgO–Ta₂O₅–Al₂O₃–SiO₂–B₂O₃ glass system using a conventional melt-quenching method are revealed. The essential oxides of Al₂O₃ and Ta₂O₅ are primarily suitable for dense packing structures dominated by a large coordination number of oxygens. The substitution of CaO by MgO results in high dissociation energy when the glass composition falls in the peraluminous regime (Al₂O₃/[MgO + CaO] > 1). A small CTE is realized by increasing the molar ratio of Al₂O₃/MgO. According to magic-angle spinning-nuclear magnetic resonance spectra, mechanically and thermally functional oxide glasses depend on their structures. These findings facilitate the development of glass substrate applications without thermal dilatation.     

Performance of V2O5/NPTiO2–Al2O3-nanoparticle- and V2O5/NTiO2–Al2O3-nanotube model catalysts in the SCR–NO with NH3

In this study, the NO reduction by NH₃ over V₂O₅/NPTiO₂–Al₂O₃ (nanoparticles) and V₂O₅/NTiO₂–Al₂O₃ (nanotubes) catalysts synthesized by the sol–gel method with 10 and 5 wt.% of Al₂O₃ and V₂O₅, respectively, is reported. The V₂O₅/NPTiO₂–Al₂O₃ and V₂O₅/NTiO₂–Al₂O₃ catalysts showed remarkable conversion, high acidity, structure stability, N₂ selectivity and a high resistance to deactivation in the presence of 10 vol.% of H₂O within the 200 to 500 °C temperature interval. The nanostructured catalysts developed in this work are an excellent alternative to improve the SCR–NH₃ process, both expanding its operation window and preventing deactivation by H₂O at high temperatures.     

Hydrothermal synthesis,crystal structure and electrochemical behavior of two new isomorphic layered vanadates: [M(dpa)V3O8.5] (M = Cu(II) 1 and Zn(II) 2; dpa = 2,2′-dipyridylamine)

Two new isomorphic vanadates, [M(dpa)V₃O_8.5] (M = Cu²⁺ 1, Zn²⁺ 2; dpa = 2,2′-dipyridylamine) have been synthesized hydrothermally. X-ray crystal analysis reveals that vanadates 1 and 2 exhibit a layered structure constructed from {V₃O_8.5}^2? layers inlaid with [M(dpa)]²⁺ subunits. The {V₃O_8.5}^2? layers consist of ribbon-like chains of edge sharing {VO₅} square pyramids bridged through {V₂O₇} fragments. Electrochemical measurement shows that lithium ions are reversibly intercalated and deintercalated in vanadate 1.     

Preparation of Mn2+-Cu+ co-doped P2O5–ZnO–Al2O3 glasses and their red fluorescence properties

To make a Mn²⁺-doped red glass phosphor that can be excited with ultraviolet (UV) light of light-emitting diodes (LEDs), 60P₂O₅-35ZnO-5Al₂O₃-8MnO-xCu₂O glasses (x = 0-1.00) were prepared by a melt-quenching method at 1200-1400°C for 30-180 minutes in atmospheric air, and the redox of Mn and Cu as well as fluorescence properties were investigated. The Mn²⁺ ion was not reduced and oxidized in the melting, quenching, and annealing processes. The valence of Cu in the glasses changed in the order of 0, 1+, and 2+ with the increase in the amount of Cu₂O and in the melting temperature and time. In this study, a 60P₂O₅-35ZnO-5Al₂O₃-8MnO-0.10Cu₂O glass melted at 1250°C for 90 minutes, having the highest Cu⁺ concentration, showed the strongest Mn²⁺ red fluorescence under the UV light at 275 nm. This strong Mn²⁺ red fluorescence has been caused by the energy transfer from excited Cu⁺ ions to Mn²⁺ ions.     

Elucidating the influences of Tantalum (V) oxide in Bi2O3–TeO2–ZnO ternary glasses: An experimental characterization study on optical and nuclear radiation transmission properties of high-density glasses

We report the optical and experimental gamma-ray and neutron attenuation properties of tantalum pentoxide reinforced Bi₂O₃–TeO₂–ZnO ternary glasses with a nominal composition of 10Bi₂O₃–70TeO₂-(20-x)ZnO-xTa₂O₅ (where x = 0,2,4, and 6 mol%). Measurements of transmittance and absorbance spectra for all of the synthesized samples are performed with Analytik Jena Specord 210 plus device between the range of 190–1100 nm. Moreover, ¹³³Ba and ²⁴¹Am/Be sources are utilized for experimental gamma-ray and neutron attenuation studies of BTZT glasses. According to results, the absorption edge is consistently moved from 380 nm to 390 nm as a result of ZnO/Ta₂O₅ translocation. In addition to decrease in optical band gap values of glass series, the fact that doping the structure containing Ta₂O₅ is lead to an increase in Urbach energies. The obtained irregularity through an increasing Ta₂O₅ additive is also changed the overall nuclear radiation attenuation properties of the BTZT glasses. The gamma-ray attenuation properties are obviously enhanced within the energy range of ¹³³Ba radioisotope. The attenuation properties against fast neutron emitted from ²⁴¹Am/Be were significantly enhanced through increasing Ta₂O₅ contribution. It can be concluded that BTZT6 glass sample may be regarded as a beneficial glass composition for multifunctional applications. It can be also concluded that ZnO/Ta2O5 translocation in Bi₂O₃–TeO₂–ZnO ternary glasses may be regarded as a monotonic tool where the neutron attenuation properties should be strengthened in addition to gamma attenuation properties.     

Thermal Luminescence of Ho2O3-PbO-Al2O3-SiO2 Glasses Exposed to Gamma Radiation

Thermoluminescence (TL) characteristics of PbO-Al₂O₃-SiO₂: Ho³⁺ glass system mixed with different concentrations of Al₂O₃ were studied in the temperature range 0–300°C. The samples were exposed to γ-rays in the dose range of 0–5 kGy. The glow curves of the samples exposed >1.0 kGy, exhibited a dosimetric peak at about 209°C. With the increase of the dose up to 5 kGy, the TL light output increased considerably, and the peak was shifted towards higher temperature. A linear dose-dependent enhancement of the TL emission was also found for the glasses mixed with 5 and 8 mol% Al₂O₃. However, the glass mixed with 10 mol% Al₂O₃ exhibited supralinearity beyond 3 kGy. The mechanisms responsible for TL emission and enhancement of TL output were discussed in view of the results obtained from optical absorption, IR, and Raman spectral studies. The results suggested that both e⁻ and h⁺ trapped centers were generated at the deeper trap levels and gave TL emission at higher temperatures. In the dose range of 2–5 kGy, the dose–response was found to be linear and could be useful for dosimetry in commercial radiation processing of perishable food commodities.     

Tuning the interfacial reaction between CaO–SrO–Al2O3–B2O3–SiO2 sealing glass–ceramics and Cr-containing interconnect: Crystalline structure vs. glass structure

In this paper, Al₂O₃ was added to CaO–SrO–B₂O₃–SiO₂ sealing system to tailor the structure of sealing glass–ceramics and glass–ceramics/metal interfacial reaction. The addition of alumina in glasses contributes to increasing fraction of bridging oxygen in silica tetrahedral as well as the change in boron environment from three-fold to four-fold (BO₄ → BO₃). The devitrification tendency of glasses also decreases with increasing Al₂O₃ content. The condensed glass structure and increasing residual glass content play opposite roles on the interfacial reaction, consequently resulting in a maximum fraction of Cr⁶⁺ in reaction couples between Cr₂O₃ and glass containing 6 mole% Al₂O₃ at 700 °C. In addition, the good bonding can be observed at the interface between Cr-containing interconnect (Crofer 22APU) and glass containing 4 mole% Al₂O₃, held at 700 °C for 100 h. The reported results support the suitability of the prepared glass–ceramics as sealing materials for SOFC applications.     

Effects of Al2O3 addition on sintering behaviour,microstructure, and physical properties of Al2O3/vitrified bond CBN composite

The effects of Al₂O₃ content on the sintering behaviour, microstructure, and physical properties of Al₂O₃/vitrified bonds (SiO₂–Al₂O₃–B₂O₃–BaO–Na₂O–Li₂O–ZnO–MgO) and Al₂O₃/vitrified bond cubic boron nitride (CBN) composites were systematically investigated using X-ray diffraction, differential scanning calorimetry, dilatometry, scanning electron microscopy, and X-ray photoelectron spectroscopy. Various amounts of Al₂O₃ promoted the formation of BaAl₂Si₂O₈ and γ-LiAlSi₂O₆, increasing the relative crystallinity of the Al₂O₃/vitrified composite from 85.0 to 93.2%, resulting in residual compressive stress on BaAl₂Si₂O₈, thereby influencing the thermal behaviour and mechanical properties of the Al₂O₃/vitrified composite. The bulk density, porosity, flexural strength, hardness, and thermal conductivity of 57.5 wt% Al₂O₃ sintered at 950 °C were 3.12 g/cm³, 6.1%, 169 MPa, 90.5 HRC, and 4.17 W/(m·K), respectively. The coefficient of thermal expansion of the bonding material was 3.83 × 10^?6 °C^?1, which was comparable to that of CBN, and the number of N–Al bonds were increased, which boosted the flexural strength of the Al₂O₃/vitrified CBN composite to 81 MPa. The excellent mechanical properties, compact structure, and suitable interfacial bonding state with the CBN grains of the Al₂O₃/vitrified composite make it a promising high-performance bonding material for superhard abrasive tools.     

Photooxidation of iodide ion on some semiconductor and non-semiconductor surfaces

In 80% aqueous ethanol, TiO₂ (anatase), ZrO₂, ZnO, V₂O₅, Fe₂O₃ and Al₂O₃ photocatalyze the oxidation of iodide ion but CdO and CdS do not; the wavelength of illumination is 365 nm. However, Fe₂O₃ fails to bring in a sustainable photocatalysis in 60% aqueous ethanol. The photooxidation of iodide ion on TiO₂, ZrO₂, ZnO, V₂O₅ and Al₂O₃ in 60% aqueous ethanol was studied as a function of [I⁻], amount of catalyst suspended, airflow rate, light intensity and solvent composition. The metal oxides examined show sustainable photocatalytic activity. Iodine formation is larger with illumination at 254 nm than at 365 nm. The mechanisms of photocatalysis on semiconductor and non-semiconductor surfaces have been discussed. Photocatalytic generation of iodine has been analyzed using a kinetic model. The photocatalytic efficiencies are of the order V₂O₅ > TiO₂ > ZrO₂ > ZnO > Al₂O₃ and V₂O₅ > TiO₂ > ZrO₂ > ZnO=Fe₂O₃ > Al₂O₃ in 60% and 80% aqueous ethanol.     

Flame-spraying synthesis of aluminate glasses in the Al2O3–La2O3 system

The paper deals with the synthesis and characterisation of binary aluminate glasses in the La₂O₃–Al₂O₃ system with Al₂O₃ contents changing between 74.6 and 86.9 mol% (48–65 wt.%), and of ternary glasses with 75.7 mol% Al₂O₃ doped with 1 mol% of Nd₂O₃ or Er₂O₃. Six binary and two ternary compositions were prepared. Flame synthesis facilitated the preparation of X-ray amorphous microspheres in the systems with 58 wt.% Al₂O₃, and with eutectic composition in the pseudobinary LaAlO₃–LaAl₁₁O₁₈ system doped with Er. Other systems contained low fractions of crystalline LaAlO₃ perovskite, regardless of the composition. The diameter of prepared microspheres ranged between 2 and 10 μm. They were transparent for visible light, as well as in the IR wavenumber range from 1300 to 4000 cm^?1.