Effect of B2O3 addition on microhardness and structural features of 40Na2O-10BaO-xB2O3-(50-x)P2O5 glass system

Phosphate glasses having composition, 40Na₂O-10BaO-xB₂O₃-(50-x)P₂O₅, wherex = 0–20 mol% were prepared using conventional melt quench technique. Density of these glasses was measured using Archimedes principle. Microhardness (MH) was measured by Vicker’s indentation technique. Structural studies were carried out using IR spectroscopy and³¹P and¹¹B MAS NMR. Density was found to vary between 2.62 and 2.77 g/cc. MH was found to increase with the increase in boron content.³¹P MAS NMR spectra showed the presence of middle Q² groups and end Q¹ and Q⁰ groups with P-O-B linkages. FTIR studies showed the presence of BO₃ and BO₄ structural units along with the depolymerization of phosphate chains in conformity with³¹P MAS NMR.¹¹B NMR spectra showed increase in BO₄ structural units with increasing boron content. The increase in MH with B₂O₃ content is due to the increase of P-O-B linkages and BO₄ structural units as observed from MAS NMR studies resulting in a more rigid borophosphate glass networks.     

IR and Raman studies and effect of γ radiation on crystallization of some lead borate glasses containing Al2O3

IR and Raman spectra of glass ceramics based on PbO-Cr₂O₃-B₂O₃glass composition system have been studied. The bands characteristic of BO₃. and BO₄ functional groups are present in all the samples. An incorporation of Al₂O₃(up to 5 mol%) in the initial glass composition considerably changes the glass network structure and relative concentrations of BO₃ and BO₄ groups. The composition 50 PbO-20 Cr₂O₃-25 B₂O₃-5 Al₂O₃(in mol%) reveals a maximum fraction of boron in the BO₄ group. A sample of this composition heat treated at 850° C for 25 h shows a maximum crystallization fraction with Pb₂O · CrO₄ as a prominent crystalline phase. The glasses irradiated with rays inhibit the crystallization into the Pb₂O · CrO₄ phase. They also show relatively smaller thermal conductivity.     

Effect of heat treatment and irradiation on electrical conductivity and crystallization in the BaO-B2O3-Fe2O3 glass system

A glass system was prepared according to the formula 75 mol % B₂O₃-(25 –x) mol % BaO –x mol % Fe₂O₃, wherex = 0, 1, 2.5, 5, 7.5 and 10. The glasses were subjected to heat treatment at 550° C for 2, 6, 12, 18 and 24 h. The glasses were also irradiated using-rays at a dose of 4.805 × 10⁴ rad h^–1 for 12, 18 and 24 h. An X-ray diffraction technique was used to identify the separated crystalline phases. The electrical conductivity and activation energy of untreated, heat-treated and irradiated samples were measured and calculated. The rate and the dimensions of crystallization were also calculated by using the Avrami equation. It was found that-Fe₂O₃ is the separated phase when a sample containing 7.5 mol% Fe₂O₃ is heat treated for 24h;-Fe₂O₃ and Fe₂O₃ are the separated phases when the sample containing 10 mol% Fe₂O₃ is heat treated for 6, 12 and 18 h, with the addition of BaO when the sample is heat treated for 24 h. A miminum value for the electrical conductivity of glass samples was found to occur around an Fe₂O₃/BaO ratio of 0.425. The rate of crystallization in the sample containing 10 mol% Fe₂O₃ is 1.30607 × 10^–3 and the geometry of crystallizationn is 1.2238, which indicates that the crystallization was in one dimension.     

Structural studies of some V2O5-P2O5-B2O3-Fe2O3 glass systems

X-ray diffraction and infrared measurements were performed on vanadium borophosphate glass containing different amounts of iron ranging from 0–7.5 mol % and heat treated at 300 °C for various times. The structure and phase separation could be determined for each glass composition. V₂O₅ was the main precipitated phase in all heat-treated samples, and its amount was dependent on the heat-treatment time and Fe₂O₃ content. Also FeP was detected in samples heat treated for 24 h. The infrared measurements showed the presence of both V⁴⁺ and V⁵⁺. The symmetry of V₂O ₇ ⁴⁻ and VO ₄ ³⁻ groups was found to increase with increasing Fe₂O₃ content. It was also found that some PO₄ changed to BO₃, forming a non-bridging oxygen.     

FTIR and Raman spectroscopic investigation of some strontium–borate glasses doped with iron ions

Structural investigation of xFe₂O₃·(100 − x)[3B₂O₃·SrO] glass system, with 0 ≤ x ≤ 40 mol%, was performed by means of X-Ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies. The purpose of this work was to investigate the structural changes that appear in the 3B₂O₃·SrO glass matrix with the addition and increasing of iron ions content. The XRD pattern for the prepared samples shows that vitreous phase is present only for x ≤ 40 mol%. For sample containing 50 mol% Fe₂O₃ was evidenced the presence of a unique crystalline phase, Fe₂O₃, embedded in an amorphous matrix. FTIR data show that BO₃ and BO₄ are the main structural units of the glass system and the iron ions are located in the network. The Raman spectrum of glass matrix indicates a structure with several borate groups (di-, meta-, pyro-borate, etc.). In higher concentrations the iron ions break the regulate glass network and determines the appearance of BO₄ isolated units.     

FT-IR,Raman and UV–VIS spectroscopic studies of copper doped 3Bi<Subscript>2</Subscript>O<Subscript>3 </Subscript>·B<Subscript>2</Subscript>O<Subscript>3</Subscript> glass matix

FT-IR, Raman and UV–VIS experimental results were presented for xCuO·(100-x)[3Bi₂O₃·B₂O₃] glass system, where 0 ≤ x ≤ 50 mol%. The FT-IR measurements indicate the presence in xCuO·(100-x)[3Bi₂O₃·B₂O₃] glasses of BO₃, BO₄ units, BiO₃ pyramidal and distorted BiO₆ octahedral units and their dependence of CuO content. The Raman scattering data indicate that for 0 ≤ x ≤ 10 mol% the structure of studied glasses consist from BiO₃ pyramidal and distorted BiO₆ octahedral units, ring and chain type of metaborate groups, ortoborate and pyroborate groups. For higher concentration the Raman spectra suggest that the structure become more disordered. The FT-IR and Raman bands characteristic for CuO were not directly evidenced, but the absorption bands specific for the glass matrix are influenced by the presence of copper ions in the glass network structure. The optical absorption confirms the presence of Cu²⁺ in the CuO doped 3Bi₂O₃·B₂O₃ glass matrix.     

Study of lithium–zinc borophosphate glasses

Mixed lithium–zinc borophosphate glasses were prepared and studied in three compositional series xLi₂O–(50−x)ZnO–50P₂O₅, xLi₂O–(50−x)ZnO–10B₂O₃–40P₂O₅ and xLi₂O–(50−x)ZnO–20B₂O₃–30P₂O₅ with x = 0, 10, 20, 30, 40 and 50 mol% Li₂O. The obtained glasses were characterized by the measurements of the density (ρ), molar volume (V _M), glass transition temperature (T _g) and thermal expansion coefficient (α). For the investigation of structural changes ¹¹B and ³¹P MAS NMR and Raman spectroscopy were applied. The replacement of zinc by lithium in borophosphate glasses slightly decreases V _M and T _g, while α increases. In Li–Zn metaphosphate glasses the compositional dependence of T _g reveals a minimum, while at the borophosphate series T _g decreases monotonously with increasing Li₂O content. Chemical stability of Li–Zn borophosphate glasses is very good for glasses with x = 0–30 mol% Li₂O. Spectral studies showed in the glass series with 10 mol% B₂O₃ only the presence of BO₄ sites. In the glasses with 20 mol% B₂O₃ the presence of BO₃ and two BO₄ sites was revealed in ZnO-rich glasses and only one BO₄ site in Li₂O-rich glasses; the number of BO₃ groups decreases with increasing Li₂O content which is ascribed to the formation of P–O–Zn covalent bonds in ZnO-rich glasses.     

Linear and non-linear optics and FTIR characteristics of borosilicate glasses doped with gadolinium ions

Borosilicate glasses have been prepared using the high-temperature melt components of ingredients Gd₂O₃ doped borosilicate glasses. FTIR spectra were measured in the wavenumber range (4000–400 cm⁻¹) to explore the state and influence of Gd³⁺ ions in the structure of the glasses. Data indicated that B₂O₃ is acting as dual network formers (BO₃) and (BO₄) structural units whereas the gadolinium ions playing the role of network modifier in these glasses. Optical transmission spectra were recorded in the range 190–2500 nm and different optical parameters such as the direct and the indirect optical band gap, Urbach energy, refractive index and optical dielectric constant, have been determined. The molar refraction, electronic polarizability and the optical basicity results have been determined using the measured glass refractive indices. Gadolinium-doped borosilicate glasses are found to be characterized by different optical parameters.     

Mechanochemical synthesis of SnO-B2O3 glassy anode materials for rechargeable lithium batteries

The xSnO·(100 ? x)B₂O₃ (0 ≦ x ≦ 80) glasses were successfully prepared by a mechanical milling technique. The glass with 40 mol% SnO showed the maximum glass transition temperature of 347°C. The SnO-B₂O₃ milled glasses consisted of both BO₃ and BO₄ units, and the fraction of BO₄ units was maximized at the composition of 50 mol% SnO. The electrochemical properties of the milled glasses were examined using a simple three electrodes cell with a conventional liquid electrolyte. The glasses with high SnO content exhibited high charge capacities more than 1100 mAh g^?1 and discharge capacities more than 700 mAh g^?1 at the first cycle. The SnO-B₂O₃ milled glasses proved to work as anode materials for rechargeable lithium batteries.     

Compositional dependence of the structural and dielectric properties of Li<Subscript>2</Subscript>O–GeO<Subscript>2</Subscript>–ZnO–Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> glasses

(10Li₂O–20GeO₂–30ZnO–(40-x)Bi₂O₃–xFe₂O₃ where x = 0.0, 3, 6, and 9 mol%) glasses were prepared. A number of studies, viz. density, differential thermal analysis, FT-IR spectra, DC and AC conductivities, and dielectric properties (constant ε′, loss tan δ, AC conductivity, σ _ac, over a wide range of frequency and temperature) of these glasses were carried out as a function of iron ion concentration. The analysis of the results indicate that, the density and molar volume decrease with an increasing of iron content indicates structural changes of the glass matrix. The glass transition temperature T _g and onset of crystallization temperature T _x increase with the variation of concentration of Fe₂O₃ referred to the growth in the network connectivity in this concentration range, while glass-forming ability parameter ΔT decrease with increase Fe₂O₃ content, indicates an increasing concentration of iron ions that take part in the network-modifying positions. The FT-IR spectra evidenced that the main structural units are BiO₃, BiO₆, ZnO₄, GeO₄, and GeO₆. The structural changes observed by varying the Fe₂O₃ content in these glasses and evidenced by FTIR investigation suggest that the iron ions play a network modifier role in these glasses while Bi₂O₃, GeO₂, and ZnO play the role of network formers. The temperature dependence of DC and AC conductivities at different frequencies was analyzed using Mott’s small polaron hopping model and, the high temperature activation energies have been estimated and discussed. The dielectric constant and dielectric loss increased with increase in temperature and Fe₂O₃ content.     

Structural changes induced by Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> addition in strontium-borate glass matrix

Glasses of the xFe₂O₃·(100−x)[B₂O₃·SrO] system, with 0 ≤ x ≤ 30 mol% were studied by X-ray diffraction, density, optical microscopy and FT-IR spectroscopy measurements. The X-ray patterns for the prepared system show that vitreous phase is present only in the sample with x < 40 mol%. For x ≥ 40 mol% in the studied samples is evidenced crystalline phase of Fe₂O₃. SEM measurements for the sample with x = 40 mol% shows that there are formed Fe₂O₃ microcrystallites with 10–20 μm dimension. FT-IR spectroscopy measurements shown that BO₃ and BO₄ are the main structural units of the glass system and the iron ions are located in the glass network.     

Raman spectroscopic investigation of sodium borosilicate glass structure

Raman spectra of sodium borosilicate glasses with a wide range of Na₂O/B₂O₃ ratios were systematically measured. Variations of the spectra with glass composition were studied to interpret the implied distribution of Na⁺ ions between silicate and borate units. When Na₂O/B₂O₃ is less than 1, all Na⁺ ions are associated with borate units as indicated by the absence of the 1100 cm⁻¹ band of Si-O⁻ non-bridging bond stretching. For the (1−x)Na₂O · SiO₂ ·xB₂O₃ glass withx≦0.4 the peak-height ratio of the 950 cm⁻¹ band to the 1080 cm⁻¹ band was used to analyse semiquantitatively the distribution of the Na⁺ ions between silicate and borate units. Sodium ions are divided between silicate and borate units approximately in proportion to the amount of SiO₂ and B₂O₃ present in these glasses. Some of the high sodium content glasses were crystallized and their spectra were compared with the bulk glass spectra. The distribution of Na⁺ ions in the glass was quite different from their distribution after crystallization. Spectra of high silica glasses that had been heat-treated for phase separation indicated exclusion of borate units from the silica network and the formation of borate groups. For high boron content glasses, no change was observed on heat treatment. Raman bands due to borate groups seem to be little affected by their environments. Also affiliated with the Department of Geosciences.     

Preparation and Characterization of Eu<Superscript>3+</Superscript>-Doped Transparent Oxyfluoride Glasses

A process has been proposed for the preparation of oxyfluoride glasses based on the SiO₂–B₂O₃–Bi₂O₃–ZnO–CaF₂ system at various ratios of batch components, and transparent glasses have been obtained at a temperature below 1000°C. According to X-ray diffraction data, all of the glasses are X-ray amorphous. The surface morphology of the glasses has been examined and their glass transition temperatures have been determined. Their local structure has been studied by IR spectroscopy and it has been shown that, independent of composition, the glasses contain complex polyborate anions formed by [BO₃] and [BO₄] groups. Bismuth is incorporated into the glass network to form Bi–O–Si bonds and [BiO₆] network-formers.     

Spectroscopic investigations of Cu2+ in Li2O-Na2O-B2O3-Bi2O3 glasses

Pure and copper doped glasses with composition,x Li ₂ O-(40-x)Na ₂ O-50B ₂ O ₃-10Bi ₂ O ₃,have been prepared over the range 0 ≤ x ≤ 40. The electron paramagnetic resonance (EPR) spectra of Cu²⁺ ions of these glasses have been recorded in the X-band at room temperature. Spin Hamiltonian parameters have been calculated. The molecular bonding coefficients, α² and β², have been calculated by recording the optical absorption spectra in the wavelength range 200–1200 nm. It has been observed that the site symmetry around Cu²⁺ ions is tetragonally distorted octahedral. The density and glass transition temperature variation with alkali content shows non-linear behaviour. The IR studies show that the glassy system contains BO₃ and BO₄ units in the disordered manner.     

Synthesis, structural and magnetic characterization of iron-zinc-borate glass ceramics containing nanocrystalline zinc ferrite

Two different glass ceramics with the composition of the (Fe₂O₃)_x·(B₂O₃)_(60−x)·(ZnO)₄₀, where x = 12.5 and 15 mol%, have been synthesized using the melt-quench method. The X-ray diffraction (XRD) patterns show the presence of nanometric zinc ferrite (ZnFe₂O₄) crystals, with spinel structure, in a glassy matrix after cooling from melting temperature. The estimated amount of crystallized zinc ferrite varies between 16 and 35%, as a function of the chemical composition. Glass transition (T_g), crystallization (T_p) and melting (T_m) temperatures were determined by differential thermal analysis (DTA) investigations. Fourier transform infrared (FTIR) data revealed that the BO₃ and BO₄ are the main structural units of these glass ceramics network. FTIR spectra of these samples show features at characteristic vibration frequencies of ZnFe₂O₄. Electron paramagnetic resonance (EPR) measurements show the presence of isolated Fe³⁺ ions predominantly situated in rhombic vicinities and as well as the Fe³⁺ species interacting by dipole–dipole interaction or to their superexchange coupled pairs in clustered formations. The magnetic properties of the studied glass ceramics were investigated by vibrating sample magnetometer (VSM). From the magnetization curves for glass ceramic containing 15 mol% Fe₂O₃ it was found that the nanoparticles exhibit ferromagnetic interactions combined with superparamagnetism with a blocking temperature, T_B. For studied samples the hysteresis is present. The coercive field is dependent on composition and magnetic field being around 0.05 μ_B/f.u for measurements performed in maximum 0.4 T.     

Surface crystallization and second-order optical non-linearity in Gd2O3–Bi2O3–B2O3 glasses

Some ternary Gd₂O₃–Bi₂O₃–B₂O₃ glasses are prepared, and crystallization behavior and second harmonic intensity are examined to develop new non-linear optical crystallized glasses. The glasses with Gd₂O₃ contents of 8–14 mol% have large densities of over 6 g/cm³ and large refractive indices of ～ 1.9. Transparent surface crystallized glasses consisting of two kinds of crystalline phases with different morphologies, i.e. plate shape and needle shape crystals, are fabricated by heat-treatment at temperatures between glass transition and crystallization temperatures. From second harmonic generation microscope observations, micro-Raman scattering spectra and XRD analyses, plate shape crystals are determined to be non-linear optical Gd_xBi_1KxBO₃ and needle shape crystals are Bi₃B₅O₁₂ having no second-order optical non-linearity. Since crystallized glasses consisting of Gd_xBi_1KxBO₃ crystals exhibit relatively strong SHGs, they have a high potential for application to light control devices.     

Formation of Photosensitive Layers in Alkali Germanate Glasses

The induced optical absorption spectra of 70GeO₂ ⋅ 10Ga₂O₃ ⋅ 20Li₂O glasses are measured. A process is described for producing photosensitive layers on alkali germanate glasses using ion-exchange diffusion from salt melts containing silver nitrate. The effects of the sensitizer (Ce³⁺, Fe³⁺, and Fe²⁺) and preparation, UV irradiation, and heat treatment conditions on the mechanisms of silver reduction in the surface layer of germanate glasses are examined. The results demonstrate that colloidal silver particles can be produced via ion exchange at 350°C in glasses containing 0.1 wt % Fe₂O₃. The particle diameter in a glass prepared under reducing conditions is estimated at 2.5 nm.__________Translated from Neorganicheskie Materialy, Vol. 41, No. 6, 2005, pp. 753–761.Original Russian Text Copyright © 2005 by Bocharova.     

Structural properties of lead vanadate glasses containing La3+ or Fe3+ ions

Structural properties of lead vanadate glasses containing La³⁺ or Fe³⁺ ions were investigated using X-ray diffraction, Fourier transform infrared spectroscopy and laser Raman spectroscopy. Crystalline Pb₂V₂O₇ was formed for the molar composition 66.7PbO-33.3V₂O₅. Incorporation of greater quantities of La³⁺ into lead metavanadate glass caused the crystallization of Pb₂V₂O₇. Fourier transform infrared and laser Raman spectra also suggested the presence of LaVO₄. Incorporation of Fe³⁺ ions into lead metavanadate glass, up to 20 wt% Fe₂O₃, did not cause crystallization inside the glass matrix. Changes in the vibrational spectra are discussed.     

The local structure of bismuth borate glasses doped with europium ions evidenced by FT-IR spectroscopy

Glasses of the xEu₂O₃ · (100 − x)[4Bi₂O₃ · B₂O₃] system, with 0 ≤ x ≤ 40 mol% were studied by FT-IR spectroscopy and density measurements. FT-IR spectroscopy and density data suggest that the europium ions play the network modifier role in the studied glasses. These data show that the glass structure consists on the BiO₃, BiO₆, BO₃ and BO₄ units, and the conversion among these units mainly depends on the Eu₂O₃ content.     

Dielectric and electrical properties of MoO3-doped borophosphate glass: dielectric spectroscopy investigations

A series of (50 ? x) P₂O₅–20B₂O₃–20CaO–10Na₂O (x?=?0–15 mol% MoO₃) glass composition was prepared. Glass structure was analyzed using infrared absorption, UV–visible spectroscopy, electron spin resonance, density, and molar volume calculations. FTIR confirmed that Mo ions are contributed as MoO₆ octahedral units in the glassy matrix, resulting in an increase in the pyrophosphate and BO₃ groups at the expense of metaphosphate and BO₄ units. UV–visible and ESR spectra detected Mo³⁺ and Mo⁵⁺ ions as species in the host glass due to the increase in MoO₃ content. Broadband dielectric spectroscopy investigation on a broad range of frequencies and at different temperatures indicated that the enhancement of electrical conductivity of the prepared glasses due to molybdenum doping was prevented using confinement effect at the wells, causing demobilization of the charge carriers. Hence the dielectric spectra were caused by the mobility of charge carriers rather than the dynamics at the molecular scale. There is a clear correlation between the transport mechanism and dynamics at the interface of the charge carriers. Presently, the challenge is to understand if optimizing the accumulation of charges at the interfaces and electrodes is the origin of electrical storage energy.