COMPOSITION EFFECTS OF Al 2 O 3 ON FTIR AND DTA IN LITHIUM BORATE GLASSES (original) (raw)
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STRUCTURAL INVESTIGATION OF Li2O-B2O –Al2O3 GLASSES BY XRD, DTA AND DENSITY MEASUREMENT
Glasses of the 30 Li2O – (70 – x) B2O3 - x Al2O3 system (where x = 0, 5, 10, 15, 20) were prepared by melt quenching technique and investigated by XRD, DTA and density measurement. The XRD analysis of prepared sample confirms the nature of sample. The density and molar volume studies reported the change of structure with the increases of aluminum content. The DTA measured glass transition temperature (Tg) of samples, glass forming ability (GFA) and glass stability (GS).
Applied Sciences
In this study, a series of Li2O-Al2O3-B2O3 glasses doped with various concentrations of Dy2O3 (where x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 mol%) were prepared by using a conventional melt-quenching technique. The structural, physical and optical properties of the glasses were examined by utilising a variety of techniques instance, X-ray diffraction (XRD), UV–Vis-NIR spectrometer, Fourier transform infrared (FTIR) and photoluminescence (PL). The XRD spectra demonstrate the amorphous phase of all glasses. Furthermore, the UV-vis-NIR spectrometers have registered optical absorption spectra a numbers of peaks which exist at 1703, 1271, 1095, 902, 841, 802, 669, 458, 393 and 352 nm congruous to the transitions from the ground of state (6H15/2) to different excited states, 6H11/2, 6F11/2 + 6H9/2, 6F9/2 + 6H7/2, 6F7/2, 6F5/2, 6F3/2, 4F9/2, 4I15/2, 4F7/2 and 6P7/2, respectively. The spectra of emission exhibit two strong emanation bands at 481 nm and 575 nm in the visible region, which corre...
Thermal and mechanical properties of lithium borate glasses in relation to the glass structure
1999
In lithium borate glasses RLi 2 O⋅B 2 O 3 (0≤R<0.4), the following experimental results were obtained: 1. The density increases monotonically with increasing R. 2. Both velocities of longitudinal and transverse ultrasonic waves increase monotonically with increasing R. 3. The elastic constants such as bulk modulus and Young's modulus increase monotonically with increasing R. 4. The linear expansion coefficient shows a broad minimum at around R=0.25. 5. The Poisson ratio shows a minimum at around R=0.10 and a maximum at around R=0.20. 6. Each of the temperature coefficients of velocities for longitudinal and transverse ultrasonic waves shows a sharp minimum at R=0.10 and a sharp change in slope at R=0.20. The experimental results 1, 2 and 3 can be ascribed to a change in short-range order groups. The experimental result 4 is ascribable to the most compact configuration at around R=0.25. The experimental results 5 and 6 are ascribable to a change in crosslink between six-membered borate rings.
STRUCTURE, THERMAL PROPERTIES AND MIXED ALKALI EFFECT IN Li2O AND Na2O DOPED BORATE GLASSES
Journal of emerging technologies and innovative research, 2018
The thermal and structural properties of melt-quenched Li2O and Na2O doped borate glasses were investigated. The noncrystalline nature of the as-quenched samples has been established by XRD studies. The structural and thermal properties of the present glasses have been studied using Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The formation of both BO3 and BO4 units in the studied samples has been ascertained by the FTIR studies. The nonlinear variation of peak positions of B-O bonds of stretching vibrations validate the occurrence of mixed alkali effect. The glass transition temperature (Tg) and thermal stability (∆t) exhibited a non-linear variation with increase in (Li2O+Na2O) content. With increasing the concentration of dopants, the Tg and ∆t respectively exhibited maxima and minima at x=0.30. This kind of behavior has been attributed to the structural modifications occurring in the network as a function of compositional variation. This is considered to be the signature for a possible mixed alkali effect taking place in the present glass systems.
Glasses with composition xFe2O3(30 x)Li2O70B2O3 (x = 0, 2, 5, 7 and 10 mol%) were prepared via meltquenching technique and their physical, thermal and dielectric properties are discussed. XRD was carried out to confirm the amorphous nature of prepared glasses. Density (r) and molar volume (Vm) were found to increase with increase in Fe2O3 content. Infrared absorption spectra depicted that Fe2O3 is acting as a network modifier. DTA has been carried out to determine glass transition temperature (Tg) and crystallization temperature (Tx). Electrical properties have been studied using impedance spectroscopy and dc conductivity. The dc conductivity decreases and activation energy increases on replacing Li+ ions with Fe3+. The impedance measurements reveal that the total conductivity obeys Jonscher’s power law. Study of the equivalent circuit analysis up to a temperature of 523 K shows a significant change in the equivalent circuitry with change in temperature and composition.
Critical Analysis of Glass Stability Parameters and Application to Lithium Borate Glasses
Journal of the American Ceramic Society, 2011
We reevaluated nine parameters of glass stability (GS) against crystallization determined from differential scanning calorimetry (DSC) experiments to predict the glass-forming ability (GFA) of oxide liquids on cooling. Then, borate glasses were prepared and tested, covering the Li 2 O-B 2 O 3 system with 20.0-66.7 mol% lithia. The glasses were prepared from both commercial chemical and powders, obtained by a solution method. The GS parameters were calculated using characteristic glass transition, crystallization, and melting peaks of DSC thermograms. We found that seven stability parameters give similar trends for compositions up to 33.3 mol% lithia, where, as we expected, GS significantly decreases with lithia content. Thereafter, up to 66.7 mol% lithia, GS shows a broad shallow maximum, but is approximately constant indicating that, surprisingly, composition does not significantly affect the GFA in this wide compositional range. This result qualitatively agrees with our successful experience of preparing glasses with compositions up to 74 mol% lithia and corroborates the adequacy of simple DSC tests to comparatively gauge the GS and GFA of glass-forming liquids.
Structural and dynamical properties of some lithium borate glasses
Journal of Non-Crystalline Solids, 1988
Structural and dynamical properties of some lithium borate glasses have been investigated by means of X-ray diffraction studies and molecular dynamics (MD) calculations. The structure of lithium borate glasses appears to consist of randomly connected planar BO 3 triangles and BO 4 units. A comparison of the slowly quenched glasses (studied by X-ray diffraction) and lastly quenched glasses (studied by MD simulations) leads to the conclusion that a small quench rate leads to a preponderance for the B-O-B angles of adjacent BO 3 triangles to 120 o. The frequency spectra of B-O vibrations in the MD simulations agree qualitatively with infrared transmission spectra.
The glass transition temperature of lithium-alkali borates
Journal of Non-Crystalline Solids, 1991
Glass transition temperatures, Tg, were measured for mixed lithium-alkali borate glasses over wide ranges of composition in samples prepared from both oxide and carbonate starting materials. Raman spectroscopy was used to compare samples prepared from different sets of starting materials. Differences in Tg were observed as a function of alkali. At low alkali content Li-Na borates had the greatest Tg and Li-Cs borates the least, while at high alkali contents the trends were reversed. Differences were also seen between samples prepared from carbonates when compared with oxides for the Li-Rb and Li-Cs systems with the carbonate-based glasses having higher Tg. No such differences were found in the Li-Na case. The trends of the data were explained in terms of models for the atomic arrangements. At low alkali contents, the dependence of Tg on the fraction of four-coordinated borons was invoked while at high alkali contents differences between orthoborate unitstetrahedral in the cases of Rb and Cs and trigonal in the sodium and lithium systems -were used. The Tg trends were also compared with density and glass formability observations.
Effect of BaTiO3 on the structural and optical properties of lithium borate glasses
Ceramics International, 2015
The conventional melt quenching technique was used to fabricate the glass samples with addition of barium titanate (BT) into (70B 2 O 3-29Li 2 O-1Dy 2 O 3) glass matrix. The glassy nature of the samples was confirmed from X-ray diffraction studies. Increase in density and the decrease in molar volume of the glass samples indicated the compactness of glass network upon addition of BT. FTIR studies revealed the progressive conversion of trigonal BO 3 units into tetrahedral BO 4 structural units with increasing BT content. The Raman spectra illustrated a remarkable shifting of Raman scattering peaks to the lower/higher wavenumber as the concentration of BT is increased. DSC studies were carried out on the samples to determine their glass transition and crystallization temperatures. The study of the optical data obtained from the prepared samples showed a decrease in both the indirect and direct optical band gap energies with an increase in BT content. The influence of the BT addition on molar refractivity, molar polarizability and metallization criterion has also been studied and the values of metallizatin criterion suggest the applications of these glasses in nonlinear optical devices.