Oxygen Molar Volume Research Articles

Characterization of new Sb2O3-based multicomponent heavy metal oxide glasses

New Sb2O3-based multicomponent heavy metal oxide glasses in the Sb2O3–Na2O–WO3–PbO system were prepared using a conventional melt-quenching technique. Glass formation behavior of these glasses and their thermal, physical and structural properties were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS), differential scanning calorimetry (DSC), UV–Vis–NIR spectroscopy and Fourier transform infrared (FTIR) spectroscopy analyses according to the increasing PbO concentration by keeping the Sb2O3/WO3 ratio constant. Thermal analysis of the glasses were realized in terms of glass transition temperature (Tg), crystallization temperature (Tc/Tp), glass stability against crystallization (ΔT), activation energy of the glass transition reaction (Eg) and fragility parameter (m). Density (ρ), molar volume (VM), oxygen molar volume (VO), oxygen packing density (OPD), refractive index, band gap energy (Eg), average cross-link density (nc‾), number of bonds per unit volume (nb) and Poisson’s ratio (μcal) values were calculated for the interpretation of physical and structural properties of the glasses. FTIR spectra of the glasses were evaluated in terms of structural transformations on the glass network.

Preparation and characterization of TeO2–WO3–Li2O glasses

Glasses in the TeO2–WO3–Li2O system were prepared by using conventional melt-quenching technique. Glass formation range of the system and thermal, physical and structural features of the ternary glasses were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and FTIR analysis according to the equimolar substitution of TeO2 by WO3+Li2O and increasing Li2O content at constant TeO2. Thermal behavior of the glasses was studied in terms of glass transition temperature (Tg), crystallization temperature (Tc/Tp) and glass stability against crystallization (∆T). Density (ρ), molar volume (VM), oxygen molar volume (VO), oxygen packing density (OPD), average cross-link density (n—c), Poisson's ratio (μcal) and number of bonds per unit volume (nb) values were calculated for the physical investigation of the glasses. FTIR spectra of the glasses were interpreted in terms of the structural transformations on the glass network by the changing composition.

Glass Formation and Characterization Studies in the TeO2–WO3–Na2O System

Glass formation behavior of the TeO2–WO3–Na2O system was studied by using conventional melt‐quenching technique. A wide glass formation range was determined for the first time in the literature and thermal, physical, and structural characterization of sodium‐tungsten‐tellurite glasses were realized using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy techniques. Glass transition (Tg) and crystallization (Tc/Tp) temperatures, glass stability (∆T), density (ρ), molar volume (VM), oxygen molar volume (VO), and oxygen packing density (OPD) values and structural transformations in the glass network were investigated according to the equimolar substitution of TeO2 by Na2O+WO3 and changing Na2O or WO3 at constant TeO2.

UV spectroscopy, refractive indices and elastic properties of the (76 − x) TeO2·9P2O5·15ZnO·xLiNbO3 glass

Tellurite glass with composition (76 − x) TeO2·9P2O5·15ZnO·xLiNbO3 (where x = 12.5, 25, 30 and 35 in mol%) have been prepared by melt-quenching method. The optical properties of the glass were estimated by measuring UV–VIS spectroscopy and refractive indices at different wavelength. From the absorption edge studies, the optical energy gap (Eopt) and Urbach energy (ΔE) has been evaluated. Moreover mechanical properties with structural properties of the glasses were investigated by measuring both longitudinal and shear velocities by using the pulse-echo overlap technique at 5 MHz. The elastic moduli such as: longitudinal (λ), shear (μ), bulk (B) and Young’s (Y) increase with the increase in LiNbO3 content in the prepared glasses matrix. The different physical parameters such as density, molar volume, oxygen molar volume, oxygen packing density, molar polarizability, Debye temperature, microhardness, Poisson's ratio, kinetic fragility and fractal bond connectivity have been computed and were found to depend on the glass composition.

Niobium doped BGO glasses: Physical, Thermal and Optical Properties

IR- transparent niobium substituted heavy metal oxide glass system in formula composition (100-x) BGO75- xNb2O5; 5 ≤ x ≤ 25 was fabricated by quenching and press molding technique. Glassy state was confirmed by XRD. Density ρexp varied 6.381 g/cc-7.028 g/cc ±0.06%. Modifying behavior of Nb2O5 was corroborated by rate of increase in theoretical volume Vth, measured volume Vexp and oxygen molar volume VMO -2 . Nb 5+ had larger cation radius and greater polarizing strength as compared to Ge 4+ ions. It replaced Ge 4+ sites introducing more NBOs in the network. Transformation temperatures Tg, Tx and Tp1 were 456 -469 o C ±2 o C, 516 -537 o C ±2 o C and 589 -624 o C ±2 o C respectively. In the range from room temperature to 400 o C the coefficient of linear thermal expansion α was 5.431±0.001*10 -6 K -1 to 7.333±0.001*10 -6 K -1 . ΔT = Tx-Tg and ΔTP1 = TP1-Tg varied collinearly with increase in niobium concentration and revealed thermal stability against devitrification. The direct bandgap Eg values lay in 3.24 -2.63 eV ±0.01 eV range and decreased due to impurity states of Nb 5+ within the forbidden band. Mobility edges obeyed Urbach law verifying amorphousness of the compositions. The IR-transparency window extended from 0.38 -6.1 μm in MIR which is wider than binary BGO glass as well as BGO single crystal.

Effect of niobium doping on physical, thermal, and spectral parameters of infrared transmitting BGO70 glasses

Heavy metal oxide glasses doped with 2d transition metal niobium were casted through normal melt-quench technique in the formula composition (100−x) [3Bi2O3–7GeO2 (BGO70)]−xNb2O5 where 5 ≤ x ≤ 25. Experimentally measured values of density dexp were 6.737–7.149 g/cc ± 0.06 %. Corresponding molar volume Vm exp had values 29.677–31.550 cc ± 0.04 %, Vpyc varied 32.28–34.71 cc ± 0.03 % and oxygen molar volume \( V_{{{\text{mO}}^{2-} }} \) increased linearly from 17.761 to 20.467 cc ± 0.06 %. Thermal coefficient of linear expansion was between 5.316 ± 0.001 × 10−6 and 8.033 ± 0.001 × 10−6 K−1. Glass transition temperature Tg, onset of crystallization temperature Tx, and the stability factor ΔT were noted from DTA curves. Direct allowed energy gap Eg was between 1.809–2.988 eV and Urbach energy had value 0.32–1.49 eV. Maximum transmission efficiency was 74 % for glass BGO70-Nb10. FTIR spectra revealed that lattice vibration modes were active in 400–1,300 cm−1 range. A modifying behavior was assigned to Nb5+ ion in the system.

Characterization of B2O3 and/or WO3 containing tellurite glasses

Abstract Characterization of B 2 O 3 and/or WO 3 containing tellurite glasses was realized in the 0.80TeO 2 –(0.20 − x )WO 3 − x B 2 O 3 system (0 ≤ x ≤ 0.20 in molar ratio) by using differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectrometry techniques. Glasses were prepared with a conventional melt-quenching technique at 750 °C. To recognize the thermal behavior of the glasses, glass transition and crystallization temperatures, glass stability value, glass transition activation energy, fragility parameter were calculated from the thermal analyses. Density, molar volume, oxygen molar volume and oxygen packing density values were determined to investigate the physical properties of glasses. Fourier transform infrared spectra were interpreted in terms of the structural transformations on the glass network, according to the changing B 2 O 3 and/or WO 3 content. Crystallization behavior of the glasses was investigated by in situ X-ray diffraction measurements and microstructural characterization was realized by scanning electron microscopy and energy dispersive X-ray spectrometry analyses.

Glass formation area and characterization studies in the CdO–WO 3–TeO 2 ternary system

The glass formation area in the CdO–WO 3–TeO 2 ternary system was determined and thermal and structural features of the ternary glasses were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Raman scattering methods and the variation of the glass properties and structural transformations were discussed in terms of the glass composition comparing with the literature. For all ternary glass samples, the glass transition ( T g) and crystallization ( T c/ T p) temperatures, glass stability (Δ T), activation enthalpy for glass transition (Δ H * ) and fragility parameter ( m) values were calculated from the DSC thermograms. Density ( ρ), molar volume ( V M ) and oxygen molar volume ( V O ) values and the refractive indices ( n) at a wavelength of 632 nm were measured. Raman spectra of the glasses were interpreted in terms of the structural transformations on the glass network resulted by the changing WO 3 + CdO/TeO 2 ratio.

The structural and spectroscopic investigations of ternary tellurite glasses, doped with copper

Infrared, EPR and optical absorption studies on (100 − 2 x)TeO 2– xAg 2O– xWO 3 (7.5 ≤ x ≤ 30) glasses containing Cu 2+ spin probe have been carried out. The infrared spectral studies show that the structure of glass network consists of [TeO 4], [TeO 3]/[TeO 3+1], [WO 4] units in the disordered manner. Physical parameters such as density ( ρ), molar volume ( V m), oxygen packing density (OPD), oxygen molar volume ( V O), copper ion concentration ( N) and mean copper ion separation ( R) have been determined. The spin-Hamiltonian parameters ( g ||, g ( and A ||) of Cu 2+ ions in the present glasses have been estimated from EPR spectra at 300 K. Bonding parameters such as α 2, β 1 2 , β 2, Γ σ, Γ π have been calculated from both optical absorption and EPR data. The observed variations in spin-Hamiltonian parameters and bonding parameters have been correlated to the structural modifications due to the WO 3 and Ag 2O incorporation into the TeO 2 glass network.

Vibrational, EPR and optical spectroscopy of the Cu 2+ doped glasses with (90–x)TeO 2–10GeO 2–xWO 3 (7.5 ≤ x ≤ 30) composition

Infrared, EPR and optical absorption studies on (90–x)TeO 2–10GeO 2–xWO 3 (7.5 ≤ x ≤ 30) glasses containing Cu 2+ spin probe have been carried out. The Infrared spectral studies show that the structure of glass network consists of [TeO 4], [TeO 3]/[TeO 3 + 1 ], [WO 4], [WO 6] and [GeO 6] units in the disordered manner. Physical parameters such as density (ρ), molar volume (V m), oxygen packing density (OPD), oxygen molar volume (V o), optical basicity (Λ), oxide ion polarizability ( α O 2− ), inter ionic distances and the concentration of ions per unit volume of Te, Ge, W, Cu and O have been determined. The spin-Hamiltonian parameters (g ||, g ⊥ and A ||) of Cu 2+ ions in the present glasses have been estimated from EPR spectra at 300 K. Bonding parameters such as α 2, β 1 2, β 2, Γ σ, and Γ π have been calculated from both optical absorption and EPR data. The observed variations in spin-Hamiltonian parameters and bonding parameters have been correlated to the structural modifications due to the WO 3 incorporation into the TeO 2 glass network at constant 10 mol% GeO 2 content.

Vibrational spectral analysis of structural modifications of Cr 2O 3 containing oxyfluoroborate glasses

Infrared and Raman spectra of oxyfluoroborate glasses of the compositions 20CaF 2–20 ZnO–(60-x) B 2O 3-x Cr 2O 3 with 0 ≤ × ≤ 0.10 mol% (x = 0, 0.02, 0.04, 0.05, 0.06, 0.07, 0.08 and 0.1) have been analyzed in order to explain the role of Cr 2O 3 on the structure of these glasses. Density, molar volume, oxygen molar volume and oxygen packing density are determined to explain the packing of the atoms in the glasses. From these studies, the existence of different borate groups like di-, tri-, tetra-, penta-, ortho-, pyro- and metaborates in these glasses is established. With the increase in the concentration of Cr 2O 3 up to 0.06 mol%, conversion of BO 3 units into BO 4 units and above this mole fraction the reconversion of BO 4 units into BO 3 units is observed. The breaking and reforming of the boroxol ring is explained from the Raman spectral studies of these glasses.

Optical band gap, glass transition temperature and structural studies of (100 − 2 x)TeO 2– xAg 2O– xWO 3 glass system

Optical absorption, differential scanning calorimetry (DSC) and Raman studies have been carried out on (100 − 2 x)TeO 2– xAg 2O– xWO 3 (7.5 ≤ x ≤ 30) glass system. The Raman spectra showed that the structure of glass network consists of [TeO 4], [TeO 3]/[TeO 3+1], [WO 4] units. The glass transition temperature ( T g ) values were measured from DSC thermogram and the variation in T g has been discussed in terms of physical parameters like number of bonds per unit volume ( n b ), average cross-link density ( n c ¯ ), average stretching force constant ( F ¯ ), oxygen molar volume ( V o ) and oxygen packing density (OPD) values. The cut-off wavelength ( λ c), optical band gap ( E opt ), Urbach energy (Δ E) and refractive index ( n) values were calculated from optical absorption data. The observed decrease in optical band gap ( E opt ), Urbach energy (Δ E) and increase in refractive index ( n) values have been discussed in terms of structural changes brought about by WO 3 and Ag 2O incorporation in to TeO 2 network.

Structure, physical and thermal properties of WO 3–GeO 2–TeO 2 glasses

Differential scanning calorimetry (DSC), optical absorption and Raman scattering studies have been carried out on (90− x)TeO 2–10GeO 2– xWO 3 glasses with 7.5 ≤ x ≥ 30 mol%. The Raman studies show that the glass system contains [TeO 4], [TeO 3+1]/[TeO 3], [GeO 6], [WO 4] and [WO 6] groups as basic structural units. From DSC thermogram, thermal properties such as the glass transition temperature ( T g), onset crystallization ( T o), thermal stability (Δ T), glass transition width (Δ T g), heat capacities in the glassy and liquid state ( C pg and C pl), heat capacity change (Δ C p) and ratios C pl/ C pg of the glass systems have been calculated. The compositional variation of the glass transition temperature ( T g) and the calculated oxygen packing density (OPD), oxygen molar volume ( V o) values have been correlated. The variations in the optical band gap energy ( E opt) and optical basicity ( Λ th) with WO 3 content have been discussed interms of the glass structure.

Physical Properties of Lithium Containing Cadmium Phosphate Glasses

Lithium cadmium phosphate glasses were prepared by melt quench technique. These glasses contain a mole % composition of x% Li2O-(50-x)% CdO-50%P2O5. The quantity x varies from 0-40 mole%. The physical properties reported in this paper are mass density ρ, modulus of rigidity η, coefficient of linear expansion α, transition temperature Tg, Softening temperature Ts, Oxygen packing density, Molar volume and lithium ion concentration. The mass density, oxygen packing density, modulus rigidity, transition temperature and softening temperature show decreasing trend with increasing concentration of lithium ions in these glasses, where molar volume and coefficient of linear expansion increases with increasing concentration of Li2O.

Structural, optical and bioactive properties of calcium borosilicate glasses

Glass of composition 40SiO 2–20B 2O 3–30CaO–10M 2O 3 (M = Al, Cr, Y and La) were prepared by the splat quenching technique to investigate the effect of M 2O 3 on their bioactivity, structural and optical properties. Y 2O 3 and Cr 2O 3 containing glasses formed a crystalline hydroxyapatite (HA) layer after dipping in simulating body fluid (SBF) for 25 days. On the other hand, HA layer could not form in Al 2O 3 and La 2O 3 glasses. However, during soaking in SBF solution, these glasses exhibit higher dissolution rate, lower density and increased optical band gap as compared to unsoaked glasses. Their oxygen molar volume was also higher than for Y 2O 3 and Cr 2O 3 glasses. The change in composition affects the cross-link formation in the glass matrix and finally its durability and bioactivity in SBF. The results show that M 2O 3 plays an important role in controlling chemical durability and bioactivity of the glasses.

Characterisation of glasses in the TeO 2–WO 3–PbO system

As potential candidates for photonic devices, non-linear materials and coatings, 22 glasses in the TeO 2–WO 3–PbO system have been formulated and prepared by conventional melting at temperatures ranging between 710 and 750 °C. The glass forming area has been determined for a wide region of the corresponding ternary diagram. Structural characterisation of the glasses was conducted through FTIR spectrometry and the variation of density values, which allowed calculation of the glass molar volume and the oxygen molar volume. UV–VIS spectra were recorded to determine optical absorption/transmission and energy gap values. Likewise, such results were correlated with the glasses composition and their ability for optical materials. DTA curves yielded data of transition temperature ( T g), onset crystallisation temperature ( T c) and the thermal stability range of glasses. Crystalline phases formed in devitrified and partially devitrified glasses were detected by X-ray diffraction. The properties and structural features of glasses were discussed in terms of their relative proportion of former/modifier oxides. The main glass former oxide is TeO 2, which arranges [TeO 4] groups with tetrahedral coordination, while PbO plays as glass modifier oxide. Tungsten oxide is incorporated as network former, alternating with TeO 2 and forming mixed linkages Te–O–W and W–O–W. WO 3 is the component that contributes most to increase the glass transition temperature, and to decrease both the oxygen molar volume and the thermal expansion coefficient.

Compositional dependence of the electrical conductivity of calcium vanadate glassy semiconductors

Scanning electron microscopy (SEM), X- ray diffraction (XRD), density (d), oxygen molar volume ( V m) and dc conductivity of different compositions of calcium vanadate glasses are reported. SEM exhibits a surface without any presence of a microstructure which is a characteristic of the amorphous phase. The overall features of these XRD curves confirm the amorphous nature of the present glasses. Density was observed to decrease with an increase in V 2O 5 content. The experimental results were analyzed with reference to theoretical models existing in the literature. It has been observed that the high-temperature conductivity data are consistent with Mott's nearest–neighbor hopping model. However, both Mott variable-range hopping (VRH) and Greaves intermediate range hopping models are found to be applicable. The hopping at high temperatures in the calcium vanadate glasses occurs by non-adiabatic process in contrast to the vanadate glasses formed with conventional network formers. The hopping model of Schnakenberg can predict the temperature dependence of the conductivity data. The percolation model of Triberis and Friedman applied to the small polaron hopping (SPH) regime is also consistent with data. The various model parameters such as density of states, hopping energy, etc., obtained from the best fits were found to be consistent with the glass compositions.

Structural and Polaronic transport properties of semiconducting CuO–V 2O 5–TeO 2 glasses

Ternary semiconducting glasses in the CuO–V 2O 5–TeO 2 system have prepared by the press-quenching technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), infrared (IR) spectra, density ( d) and oxygen molar volume ( V m) and dc conductivity ( σ) of these glasses were reported. The overall features of XRD curves confirm the amorphous nature of the present glasses. SEM exhibits a surface without any presence of microstructure which is a characteristic of the amorphous phase. Density was observed to decrease with an increase in V 2O 5 content. The network structure for the glass compositions with 57.5 mol% V 2O 5 is built up of the VO 5 polyhedra, while the other glass compositions consist of VO 4 polyhedra. The temperature dependence of the conductivity data has been analyzed in terms of different polaronic models. In high-temperature region above θ D/2 the Mott model of SPH between nearest neighbors is consistent with the conductivity data, while at intermediate temperature the Greaves VRH (variable-range hopping) model was found to be appropriate. The conduction was confirmed to obey the adiabatic SPH and was mainly due to electronic transport between V ions. The dominant factor determining conductivity was the hopping carrier mobility in these glasses.

Physical and structural properties of glasses in the TeO 2–TiO 2–Nb 2O 5 system

Twelve glasses in the TeO 2–TiO 2–Nb 2O 5 system have been prepared. The glass forming region in the TeO 2–TiO 2–Nb 2O 5 ternary system was determined. The structural role of each component was studied by FTIR and some of their physical properties (density, molar volume, oxygen molar volume, transition temperature, thermal expansion coefficient, optical absorption and energy gap) were determined. The glass structure is mainly built by [TeO 4] groups, while Nb 5+ and Ti 4+-ions play as network modifiers. As the Nb 2O 5 and TiO 2 concentration increases, [TeO 4] groups progressively change to [TeO 3] groups as a consequence of the network opening. The contribution of the three ions to the oxygen molar volume follows the order: Te 4+ > Ti 4+ > Nb 5+. TiO 2 incorporation and even more Nb 2O 5 improve the glasses thermal stability and the network reinforcement. TiO 2 is the component which contributes in the highest extent to decrease the glass energy gap.

EFFECT OF B2O3 ON PHYSICAL AND OPTICAL PROPERTIES OF ZINC PHOSPHATE GLASSES

Zinc-phosphate glasses with the addition of B 2 O 3 were prepared by using the melt quench technique. These glasses had a mol% composition of 30 ZnO -x B 2 O 3 - (70-x) P 2 O 5. The quantity x had values of 10–40 mol%. The mass density of these glasses was found to be in the range of 2.4912–3.0142 g/cm3. The oxygen packing density and molar volume were estimated to lie in the range 192.385–286.026 g-atom/liter and 46.78–31.46 cm3 respectively. The absorption spectra of these glasses were recorded in the range of 190 to 1100 nm. No sharp edges were found in the optical spectra, which confirms the amorphous nature of these glasses. The optical band gap energies were determined to be in the range of 2.40–3.00 eV. A decreasing behavior in optical band gap energy was seen due to the increasing concentration of B 2 O 3. The extent of band tailing was worked out from the Urbach plots, which showed an exponential dependence of absorption coefficients on photon energies.