The investigation of the influence of lead oxide on the formation and on the structure of lithium diborate glasses A.A. Solimana,∗, E.M. Sakra, I. Kashifb (original) (raw)
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Pseudo-binary (100 x)Li2B4O7–xPb3O4, with x = 0–70 mol% PbO have been prepared and their properties investigated. The glass transition temperature, density and molar volume have been determined as a function of composition. The values of Tg and the molar volume decrease non-linearly while the density increases as the Pb3O4 content is raised. Infrared spectra of the glasses reveal that a strong network consisting of diborate units breaks up by the addition of Pb3O4. The absorption bands below 620 cm1 show that PbO is one of the network formers of the glasses 70PPb3O4P10; as they can be associated with vibrations of (PbO4)2 grouping. PbO plays a dual role in the glass network. The calculated values of N4 [the fraction of borons which are tetrahedral] slightly decrease with PbO content up to 30 mol% and then increase with Pb3O4 content up to 50 mol%, then followed by a decrease as the Pb3O4 content rises further. The Vickers hardness of the glasses varies as a function of the PbO content in the same manner as the variation of N4. The dc conductivity decreases with the Pb3O4 concentration up to about 30 mol% and then increases thereafter.
The role of lead oxide on structural and physical properties of lithium diborate glasses
Pseudo-binary (100 x)Li2B4O7–xPb3O4, with x = 0–70 mol% PbO have been prepared and their properties investigated. The glass transition temperature, density and molar volume have been determined as a function of composition. The values of Tg and the molar volume decrease non-linearly while the density increases as the Pb3O4 content is raised. Infrared spectra of the glasses reveal that a strong network consisting of diborate units breaks up by the addition of Pb3O4. The absorption bands below 620 cm1 show that PbO is one of the network formers of the glasses 70PPb3O4P10; as they can be associated with vibrations of (PbO4)2 grouping. PbO plays a dual role in the glass network. The calculated values of N4 [the fraction of borons which are tetrahedral] slightly decrease with PbO content up to 30 mol% and then increase with Pb3O4 content up to 50 mol%, then followed by a decrease as the Pb3O4 content rises further. The Vickers hardness of the glasses varies as a function of the PbO content in the same manner as the variation of N4. The dc conductivity decreases with the Pb3O4 concentration up to about 30 mol% and then increases thereafter
Materials Science and Engineering: B, 2009
a b s t r a c t Pseudo-binary (100 − x) Li 2 B 4 O 7 ·xPbO, where x = 0, 5, 15, 25, 35, 45, 55 and 65 mol%. PbO have been investigated. The glass transition temperatures, density and molar volume have been determined. Both T g 's values and molar volume decreased non-linearly while the density increased by increase the PbO content. Infrared spectra of the glasses reveal that the strong network consisting of diborate units is break open by PbO. The absorption bands below 620 cm −1 show that PbO is one of the network former of glasses 65 ≥ PbO ≥ 5 which can be associated with vibrations due to [PbO 4 ] 2− type of grouping are become sharp and high intensities by increase PbO content. PbO plays the dual role in the glass network. The calculated values of N 4 slightly decreased by increase PbO content up to 25 mol% and then increased up to 45 mol% PbO, then decreases above it. Proving that three-coordinated boron atoms are predominant in these glass samples. The Vicker's hardness values of the glasses vary as a function of the PbO content in a manner that N 4 varied. The dc conductivity decreased by increase PbO concentration up to about 25 mol% and then increased by increase the concentration of lead oxide. Published by Elsevier B.V. (A.A. Soliman).
Journal of Non-crystalline Solids, 2007
Pseudo-binary sodium borate glasses containing (1 À y)Na 2 B 4 O 7 -yM a O b (where M a O b = PbO, Bi 2 O 3 and TeO 2 ) (y = 0.25, 0.5, 0.67 and 0.79) have been investigated. Sound velocities (longitudinal and shear) have been measured at 10 MHz frequency using quartz transducers. Density increases with increase of y and the molar volume decreases. Sound velocities also decrease with increasing y till y % 0.66 above which it increases slightly. Steeper decrease in velocities has been observed in TeO 2 containing glasses. Elastic moduli, Poisson's ratio and Debye temperature have been calculated. Glass transition temperatures have also been determined and it decreases with increase of y. T g also exhibits a dependence on the cationic charge in M a O b . Infrared spectra of the glasses reveal that the strong network consisting of diborate units is affected only by PbO and only very marginally by Bi 2 O 3 and TeO 2 . Only glasses with high concentrations of Bi 2 O 3 and TeO 2 reveal the presence of mixed bridges such as Bi-O-B and Te-O-B. Consistent with the IR spectral observations, the N 4 values of 11 B MAS-NMR remain close to the ideal value of 0.5 of the diborate composition in most of the glasses. A structural model based on the observation that the diborate network is unaffected by Bi 2 O 3 and TeO 2 where as PbO opens up and breaks the diborate units is shown to be consistent with all of the experimental observations including mechanical properties.
Lithium diobate based bismuth glasses containing erbium oxide were prepared by melt quenching technique. The density found increaseswith the increase of Bi 2 O 3 content while the molar volume is decreased. The increase in density is directly linked with the substitution of higher molecular weight of Bi 2 O 3 by lower Er 2 O 3 content. The structural groups of the glass matrix were analyzed using FTIR spectroscopy. The addition of Er 2 O 3 does not cause much to the structure of lithium diborates FT-IR spectrum revealing the absorption bands of BO 3 , BO 4. BiO 6 groups. The decrease in glass transition temperature and optical band gap energy with an increase of Bi 2 O 3 content has been explained on the basis of an increase in the formation of non-bridging oxygen atoms in the glass network.
The glass composition (90 mol% Li2B4O7–10 mol% Nb2O5) was prepared by the melt quenching technique. The quenched sample was heat treated at 480C, 545C and 630C for 5 h and heat treated at 780C with different time. The times were 5, 10, 15, 20, 28, and 36 h. The glass and glass ceramics were studied by differential thermal analysis (DTA), X-ray diffraction (XRD), and dc conductivity as a function of temperature. Lithium niobate (LiNbO3) and lithium diborate (Li2B4O7) were the main phases in glass ceramic addition to traces from LiNb3O8. Crystallite size of the main phases determined from the X-ray diffraction peaks are in the range 5100 nm. The fraction of crystalline (LiNbO3) phase increases with increase the heat treatment temperature and time. The relation between physical properties and structure were studied
Lead modified properties of molybdenum doped lithium borate glasses
Journal of Non-Crystalline Solids, 2018
The current scientific investigation deals with some significant results pertaining to the effect of substituting lead oxide on properties of lithium borate glasses having composition xPbO•(30-x)Li 2 O•70B 2 O 3 + 2 mol% MoO 3 (x = 0, 2, 5, 7, 10, 12 and 15 mol%, PLBM1-7). These glasses have been synthesized through appropriate meltquench route and the non-crystalline phase formation has been confirmed through peak free X-ray diffraction measurements. Theoretical optical basicity (Λ th), density (ρ) and molar volume (V m) are observed to increase with increase in PbO content. dc conductivity has been observed to exhibit mixed electronic-ionic behaviour. DTA has been carried out to determine glass transition (T g), crystallization (T x) and liquidus (T l) temperature. FTIR spectra depicted that PbO is modifying the structure of lithium borate matrix. The optical absorption spectra reveals that optical band gap (E opt) decreases with increasing contents of PbO at the cost of Li 2 O.
Influence of heat treatment on structure and some physical properties of lithium boro-niobate glass
The glass composition (90 mol% Li2B4O7–10 mol% Nb2O5) was prepared by the melt quenching technique. The quenched sample was heat treated at 480C, 545C and 630C for 5 h and heat treated at 780C with different time. The times were 5, 10, 15, 20, 28, and 36 h. The glass and glass ceramics were studied by differential thermal analysis (DTA), X-ray diffraction (XRD), and dc conductivity as a function of temperature. Lithium niobate (LiNbO3) and lithium diborate (Li2B4O7) were the main phases in glass ceramic addition to traces from LiNb3O8. Crystallite size of the main phases determined from the X-ray diffraction peaks are in the range 5100 nm. The fraction of crystalline (LiNbO3) phase increases with increase the heat treatment temperature and time. The relation between physical properties and structure were studied.
Effect of La2O3 on the structure of lead borate glasses
Journal of Non-Crystalline Solids, 2010
mol%) glasses have been investigated by Fourier transform infrared spectroscopy, and ultrasonics. Deconvolution of infrared spectra reveals a small increase with x in the fraction of four-coordinated boron atoms. These results show that La 3+ ions have priority to form BO 4 units at the expense of Pb 2+ ions. A minimum in the sound velocity, elastic properties and transition temperature of glasses observed at 5 mol% La 2 O 3 is correlated with the change in the packing of glass. Higher rate of increase in density for x ≥ 5 mol% is considered due to an increase in the concentration of PbO 4 units.