Lead Borophosphate Glasses Research Articles

Efficient Tm3+ up-conversion in lead borophosphate glasses for visible emission

Thulium oxide (Tm2O3) doped lithium lead borophosphate glasses have been synthesised and analysed to probe their structural and luminescence properties. X-ray diffraction data confirmed the non-crystalline nature of the prepared glasses. Participation of Tm2O3 in the structure is established by the variation in density and molar volume with increasing concentration of Tm2O3. Fourier transform infrared spectroscopy revealed the various structural units present due to B2O3, P2O5 and PbO. Ultraviolet-visible near infrared absorption spectra showed peaks/bands at 466 nm (G41), 684 nm (F33), 790 nm (H43) and 1210 nm (H53), originating from ground state H63 of thulium while Ytterbium showed its characteristic peak at 978 nm. Indirect band gap, calculated from Tauc's curve showed decreasing trend with increasing concentration of Tm2O3. The other optical parameters like molar refractivity, molar polarizability, electronic polarizability and dielectric constant also showed variation with increase in concentration of Tm2O3. Judd-Ofelt parameters followed Ω2>Ω4>Ω6 trend and oscillator strengths have also been evaluated. For luminescence studies, upon 790 nm excitation, visible peaks at 454 nm, 485 nm, 529 nm, 624 nm and 665 nm were observed while at 684 nm excitation, wavelength of 542 nm and 610 nm is emitted. Excited state absorption up-conversion mechanism is responsible for the observed visible emission. Commission Internationale de I'Eclairage (CIE) chromaticity coordinates have also been calculated and coordinates lie near the white light region. Up-conversion results indicated that the prepared glasses are potential host for up-conversion and can be used in colour displays.

Effect of silver oxide additives on structural, optical dispersion and protection features of lead boro-phosphate glasses

This work presents the structural, optical, refractive index dispersion, and shielding properties of Ag-containing lead-boro-phosphate glasses. The glasses were prepared using the classic melt-quenching method, in which the Ag2O concentration was varied in each synthesis. The precipitation of Ag NPs was proved by the appearance of the (200) crystal plane in the XRD patterns and confirmed by the homogeneous distribution of spherical agglomerates observed in TEM images. FTIR and Raman analyses have revealed a network depolymerization process resulting from the distortion of the PO4 units and the formation of Ag NPs. Therefore, the Ag ions contribute at high concentrations to an increase in the glass density and a reduction in the optical band gap energy. Ellipsometry parameters indicate that the glass becomes more optically dispersive due to the Ag NPs formation, which improves its performance for several potential applications in multi-functional optical devices. The mass attenuation factors are determined in the energy range of 15 keV–15 MeV and are very sensitive to the silver content at low energies. The Half value layer (HVL) decreases with the amount of Ag2O, indicating the improvement in the material's ability to attenuate radiation. The results show that the glass sample with the highest Ag content has the highest shielding effectiveness.

Structural, spectral and Judd–Ofelt intensity parameters of Pr3+ ion doped in sodium lead borophosphate glasses for visible LED applications

Structural, spectral and Judd–Ofelt intensity parameters of Pr3+ ion doped in sodium lead borophosphate glasses for visible LED applications

Structural and optical studies on Dy3+ ions doped alkali lead borophosphate glasses for white light applications

Dy3+ ions doped alkali lead borophosphate glasses with chemical compositions of (45-x) H3BO3+20P2O5+10Al2O3+10PbO+15Li2CO3+xDy2O3 (where x = 0.0, 0.1, 0.25, 0.50, 1.0 and 2.0 wt%) have been prepared by conventional melt quenching technique and their physical, structural and spectroscopic behavior were studied systematically through XRD, FTIR, SEM with EDAX, optical absorption, luminescence and decay measurements. The density and refractive index increase with increasing of Dy3+ ions concentration and accordingly creating more non-bridging oxygen (NBOs) into glass matrix. X-ray diffraction study proves the amorphous nature of the prepared glasses. The FTIR study reveals the presence of BO4, PO4 vibrational groups and the bending of B–O–P, P–O–P units. The surface morphology and existence of elements in the prepared glasses have been studied through SEM with EDAX. The absorption spectra exhibit nine peaks with hypersensitive transition corresponding to 6H15/2→6F11/2 at around 1270 nm. The Judd-Ofelt (JO) theory is used to calculate the calculated oscillator strengths, JO intensity parameters, radiative transition probabilities, stimulated emission cross-section and branching ratio for the present glasses. The JO intensity parameters follow the trend as Ω2>Ω6>Ω4. The luminescence spectra of the glass sample displayed three emission peaks with high intensity are centered at 478 nm and 574 nm respectively. These attractive luminescence features of the proposed glasses in the white region verified using CIE 1931 diagram useful for the development of white light applications. The decay measurements of the prepared glasses for the state 4F9/2 were measured and exhibits both single and non-exponential behavior.

Radiation Shielding Investigation of Lead Borophosphate Glasses Modified by Tungsten Oxide

Abstract The effect of tungsten trioxide (WO3) on the shielding properties of the lead(II) oxide–boron trioxide–phosphorus pentoxide–WO3 system was investigated. The mass attenuation coefficients (μ/ρ) were evaluated using the XCOM program (National Institute of Standards and Technology, Gaithersburg, MD) in the energy range of 0.015–10 MeV. The μ/ρ values were then used to calculate the mean free path (MFP) and half value layer (HVL). In addition, the macroscopic effective removal cross section for fast neutrons (ΣR) was calculated for the present glass system. It was found that the μ/ρ values increase with increasing WO3 concentration, while HVL and MFP values decrease with increasing WO3 content. The present glass system showed good radiation shielding properties by providing shorter MFP than some glass systems, such as 70TeO2-30V2O5 and 80TeO2-20MoO3 glasses. In addition, it was found that the ΣR values for the present glasses lie within the range of 0.1100–0.1132 cm−1.

Ionic conductivity, dielectric and optical properties of lithium lead borophosphate glasses combined with manganese ions

Multi–component transparent glasses of composition 20Li2O–20PbO–45B2O3–(15–x)P2O5–xMnO, with 0 ≤ x ≤ 3 mol% (x = 0, 0.2, 0.4, 0.6, 1, 2 and 3), were fabricated by the melt quenching technique. The amorphous nature of the samples was asserted by X–ray diffraction. FTIR analysis disclosed the bands due to Mn–O specific vibrations along with conventional borate and phosphate groups. EPR and optical absorption spectra were recorded at ambient temperature. The results demonstrated that manganese ions exist in Mn2+ and Mn3+ states and occupy octahedral sites in the glass network. Dielectric studies such as dielectric constant (ε′), loss (tanδ) and a.c. conductivity (σac) in the frequency range 103–106 Hz in the temperature range 30–300 °C were also carried out on these samples. These studies have revealed that the glasses exhibited semiconducting nature and such nature increases with increase in the concentration of MnO.

Characterization and structural investigation of lead borophosphate glasses modified by tungsten oxide

The effect of WO3 on the properties and structure of PbO–B2O3–P2O5–WO3 quaternary system was studied. Glasses containing up to 60 mol% WO3 were prepared and the variation of several physical properties was determined with respect to chemical composition in a broad compositional range. Chemical durability of WO3-containing glasses is very high and their thermal stability as well. Glass transition temperature increases with increasing WO3 content up to 566 °C. Glass structure was studied by Raman spectroscopy and 31P and 11B MAS NMR spectroscopy. NMR spectroscopy reveals the formation of B–O–W linkages and also the existence of tetrahedral BO4 units and trigonal units BO3 in the glass structure. With increasing WO3 content in the glasses, the number of starting tetrahedral B(OP)3O units decreases and B–O–P bridges are replaced gradually by B–O–W and B–O–B bridges, while the number of BO3 units increases. Raman spectra of the studied glasses possess a doublet of strong vibrational bands in the range at 800–1000 cm−1, assigned to vibrations of W–O− and WO bonds in tungstate structural units. In glasses with a higher WO3 content WO6 octahedra form tungstate clusters interconnected by W–O–W bridges as reflected in the Raman spectra. The formation of strong P–O–W and B–O–W linkages in the studied glasses explains high chemical durability of the glasses and the observed increase in the glass transition temperature.

Eu3+ ion doped sodium–lead borophosphate glasses for red light emission

Sodium–lead borophosphate glasses doped with different concentrations of Eu3+ ion are prepared by using the melt quenching technique to study their physical, XRD FTIR and luminescence properties to understand the lasing potentialities of these glasses. The XRD studies confirm the amorphous nature of the glasses. FTIR spectrum indicates the presence of BO3 and PO4 structural units. From the emission spectra, Judd–Ofelt (J–O) intensity parameters have been evaluated from the transition 5D0→7FJ (J=2 and 4). The evaluated (J–O) intensity parameters have been used to calculate the radiative transition probabilities, luminescence branching ratio and radiative decay times. The intensity ratio (R) value due to 5D0→7F2/5D0→7F1 transition intensity of Eu3+ ions, increase with increasing concentrations suggesting higher asymmetry and covalent bonding character between rare earth ion and oxygen ligands. The chromaticity coordinates were calculated and analyzed with Commission International deI’Eclairage color diagram. The lifetimes of 5D0 metastable state for the samples with different concentrations were also measured and discussed. The predicted and experimental lifetimes for the 5D0 level in sodium lead borophosphate glasses were compared and discussed in detail.

UV–visible and infrared absorption spectra of lead boro-phosphate glasses containing lithium oxide

Lead boro-phosphate glasses containing lithium oxide of the system xLi2O-(50-x)B2O3-40PbO-10P2O5 mol% were prepared by melt quenching technique. The infrared absorption spectra of the studied phosphate glasses indicate the presence of phosphate units with metaphosphate groups, triangular borate groups together with the sharing of PbO vibrations as the main structural constituents. The optical absorption spectra of these glasses were measured at room temperature in the wavelength range between 190 and 1100 nm. The optical band gap decreases with gradual increasing of Li2O mole content and Urbach energy of the tested glass samples increased with the increase in Li2O mol%. Density and molar volume is discussed and correlated with the structural changes within the glassy matrix.

The structural role of tellurium dioxide in lead borophosphate glasses

Lead borophosphate glasses formulated with TeO2 were prepared and studied in the compositional series (1−x)[50PbO-10B2O3-40P2O5]-xTeO2 with x=0–0.7 and glasses with 20 and 60mol% TeO2 with also the B2O3/P2O5 ratio of 5/45 and 15/35. Structural studies by 31P and 11B MAS NMR and Raman spectroscopies revealed the formation of P–O–Te bonds. The addition of TeO2 resulted in the depolymerisation of phosphate chains as revealed from the 31P MAS NMR spectra. The addition of TeO2 to the parent lead borophosphate glass resulted in the formation of B–O–Te bonds and B(OP)4−n(OTe)n mixed structural units, the number of which increases with increasing TeO2 content and also with the increasing B2O3/P2O5 ratio in the glasses. Only a small number of BO3 units (less than 4%) are formed in glasses with a higher TeO2 content and at a high B2O3/P2O5 ratio. The Raman spectra also indicated that at low TeO2 concentrations, tellurium atoms form preferentially TeO3 structural units, whereas at higher TeO2 content, TeO4 units are predominant in the glass network. With the replacement of P2O5 by B2O3 in the studied glasses, TeO4 units are converted into TeO3 units as the number of oxygen atoms in the glass decreases when the B2O3/ P2O5 ratio increases.

White light emission from Dy3+ doped sodium–lead borophosphate glasses under UV light excitation

Sodium–lead borophosphate glasses doped with different Dy3+ concentrations have been prepared and characterized through, XRD, FTIR, optical absorption and photoluminescence techniques. FTIR spectrum indicates the presence of BO3 and PO4 structural units. The optical absorption spectrum has been studied at room temperature and several bands have been observed. These bands have been assigned to the ground state 6H15/2 to several excited states. The bonding parameters have been evaluated based on the observed band positions. From the absorption spectrum, Judd–Ofelt (J–O) intensity parameters have been evaluated. By using J–O parameters radiative parameters such as transition probabilities, branching ratios and absorption cross section have been evaluated. The emission spectra have been studied for different concentrations of Dy3+ ions. The yellow/blue values due to 4F9/2→6H13/2/4F9/2→6H15/2 luminescence intensity ratios of Dy3+ ions, increase with increasing concentrations, suggesting higher asymmetry and more covalent bonding character between Dy and oxygen ligands. The chromaticity coordinates were calculated from emission spectra and analysed with Commission International deI’Eclarige Color diagram. The life time of the 4F9/2 level has been measured and found to decrease with increase in Dy3+ ions concentration.

Structural and magnetic properties of Gd3+ ions in sodium–lead borophosphate glasses

Glasses in the (30−x) (NaPO3)6+30PbO+40B2O3+x Gd2O3 system with x=0.5, 1.0, 1.5, 2.0, 2.5, and 3.0mol% have been prepared by the melt quenching method. The electron paramagnetic resonance (EPR) and FT-IR spectra of these glasses have been studied. The EPR spectra of sodium–lead borophosphate glasses at room temperature exhibit three prominent features with effective g-values of ≈5.99, 2.85 and 1.98 and weaker features at g≈3.60 and 4.77. The EPR spectra of these glasses containing 1.0mol% Gd3+ ions have been studied at different temperatures (93–303K). The spin concentration (N) participating in resonance for g≈5.99 resonance signal has been calculated as a function of Gd content and temperature. It is observed that N increases with Gd content. A linear relationship is established between logN and 1/T and the activation energy is calculated from the graph. The paramagnetic susceptibility (χ) is calculated from the EPR data at various temperatures and the Curie constant (C) and paramagnetic Curie temperature (θp) have been evaluated from the 1/χ versus T graph. The emission and excitation spectra are measured and it is found that the Gd3+ ions doped glasses exhibit good UV-excited luminescence. The IR spectra of the borophosphate glasses reveal prominent IR absorption spectrum which is characterized by well-defined bands in the far- and mid-IR region. The IR results depict the presence of BO3, BO4, and PO4 structural units. The theoretical values of optical basicity (Λth) of the glasses have also been evaluated.

Spectral studies on Cu2+ ions in sodium–lead borophosphate glasses

Electron Paramagnetic Resonance (EPR) and optical absorption spectra of Cu 2+ ions in sodium–lead borophosphate glasses doped with different concentrations of Cu 2+ ions have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of Cu 2+ ions. The values of spin-Hamiltonian parameters indicate that the Cu 2+ ions in sodium–lead borophosphate glasses are present in octahedral sites with tetragonal distortion. The optical absorption spectra of all the glass samples show a single broad band, which has been assigned to the 2 B 1g → 2 B 2g transition of Cu 2+ ions. The optical band gap energy ( E opt ) and Urbach energy (Δ E ) are calculated from their ultraviolet absorption edges. The emission bands observed in the ultraviolet and blue region are attributed to 3d 9 4s→3d 10 triplet transition in Cu + ion. The FT-IR spectra show that the glass system contains BO 3 , BO 4 and PO 4 structural units.

Use of Fe3+ ion probe to study the structural coordination in sodium–lead borophosphate glasses by utilizing electron paramagnetic resonance and optical spectroscopy

Electron paramagnetic resonance (EPR) and optical absorption spectral investigations have been carried out on Fe3+ ions doped in sodium–lead borophosphate glasses. The EPR spectra exhibit resonance signals with effective g values at g≈1.99, g≈4.30 and g≈8.40. The resonance signal at g≈8.40 has been attributed to Fe3+ ions in axial symmetry sites whereas the resonance at g≈4.30 is due to rhombic symmetry site. The g≈1.99 resonance is due to Fe3+ ions coupled by exchange interaction in a distorted octahedral environment. The EPR spectra at different temperatures (93–303K) have also been studied. The intensity of the resonance signals decreases with increase in temperature whereas linewidth is found to be independent of temperature. The paramagnetic susceptibility (χ) was calculated from the EPR data at various temperatures and the Curie constant (C) and paramagnetic Curie temperature (θp) have been evaluated from the 1/χ versus T graph. The optical absorption spectrum exhibits three bands characteristic of Fe3+ ions in octahedral symmetry. The crystal field parameter (Dq) and the Racah interelectronic repulsion parameters (B and C) have also been evaluated and discussed. The optical band gap energy (Eopt) and Urbach energy (ΔE) are calculated from their ultra-violet absorption edges. Photoluminescence spectra show prominent blue emission peaks under near band edge UV excitation. The FT-IR spectrum shows that the glass system contains BO3, BO4 and PO4 structural units.

Structural Investigations on Sodium–Lead Borophosphate Glasses Doped with Vanadyl Ions

Electron paramagnetic resonance (EPR), optical absorption, and FT-IR spectra of vanadyl ions in the sodium-lead borophosphate (Na(2)O-PbO-B(2)O(3)-P(2)O(5)) (SLBP) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO(2+) ions. The spin Hamiltonian parameters g and A are found to be independent of the V(2)O(5) content and temperature. The values of the spin Hamiltonian parameters indicate that the VO(2+) ions in SLBP glasses are present in octahedral sites with tetragonal compression. The population difference between Zeeman levels (N) is calculated as a function of temperature for an SLBP glass sample containing 1.0 mol % VO(2+) ions. From the EPR data, the paramagnetic susceptibility (χ) is calculated at different temperatures, and the Curie constant (C) is calculated from the 1/χ versus T graph. The optical absorption spectra of the glass samples show two absorption bands, and they are attributed to V(3+) and V(4+) ions. The optical band gap energy (E(opt)) and Urbach energy (ΔE) are calculated from their ultraviolet absorption edges. It is observed that, as the vanadium ion concentration increases, E(opt) decreases and ΔE increases. The study of the IR absorption spectrum depicts the presence of BO(3), BO(4), PO(3), PO(4), and VO(5) structural units.

Spectral studies on Mn 2+ ions doped in sodium–lead borophosphate glasses

Electron paramagnetic resonance (EPR), optical absorption, and luminescence spectral studies of Mn 2+ ions doped in (30− x) (NaPO 3) 6+30PbO+40B 2O 3+ xMnO 2 ( x=1.0, 2.0, 3.0, 4.0, and 5.0 mol%) glasses have been studied. The EPR spectra exhibit resonance signals with effective g value at g eff≈2.02 with six line hyperfine structure. A weak resonance signal with effective g value at g eff ≈4.3 is also observed for higher concentrations of Mn 2+ ions. The EPR spectra of x =3.0 mol% of Mn 2+ in sodium–lead borophosphate glass sample have been studied at various temperatures. It is observed that the resonance signal intensity decreases with increase in temperature. The optical absorption spectrum exhibits bands characteristic of Mn 2+ ions in octahedral symmetry. From the analysis of the bands, the crystal-field parameter Dq and the Racah interelectronic repulsion parameters B and C have been evaluated. The emission spectrum exhibits single broad band in the green region.

Spectral studies on Cr 3+ ions doped in sodium–lead borophosphate glasses

Electron paramagnetic resonance (EPR), optical absorption and emission spectra of Cr 3+ ions doped in (30− x) (NaPO 3) 6+30PbO+40B 2O 3+ xCr 2O 3 ( x=0.5, 2.0, 3.0, 4.0 and 5.0 mol%) glasses have been studied. The EPR spectra exhibit resonance signals with effective g values at g≈4.55 and g≈1.97. The EPR spectra of x=3.0 mol% of Cr 2O 3 in sodium–lead borophosphate glass sample were studied at various temperatures (295–123 K). The intensity of the resonance signals increases with decrease in temperature. The optical absorption spectrum exhibits four bands characteristic of Cr 3+ ions in octahedral symmetry. From the analysis of the bands, the crystal-field parameter Dq and the Racah interelectronic repulsion parameters B and C have been evaluated. The emission spectrum exhibit one broad band characteristic of Cr 3+ ions in octahedral symmetry. This band has been assigned to the transition 4T 2g (F)→ 4A 2g (F). Correlating EPR and optical data, the molecular bonding coefficient ( α) has been evaluated.

Study of structure and properties of modified borophosphate glasses

A review on the investigation of the structure and properties of zinc and lead borophosphate glasses is given. Structural studies with the application of Raman and infrared spectroscopy and 31P and 11B MAS NMR spectroscopy are manifested on several borophosphate glasses. Structural studies were realized in several compositional series and thus compositional dependencies and the evolution of basic structural units in the glasses was established. The modification of phosphate and borophosphate glasses with other oxides e.g. Sb2O3 and transition metal oxides like TiO2 and Nb2O5 is presented.

Structure and properties of mixed sodium–lead borophosphate glasses

Mixed sodium–lead borophosphate glasses were prepared in two compositional series xNa2O–(50−x)PbO–10B2O3–40P2O5 and xNa2O–(50−x)PbO–20B2O3–30P2O5 with x=0, 10, 20, 30, 40 and 50mol% Na2O. Their density decreases and molar volume increases slightly with increasing Na2O content. Chemical durability decreases steeply for glasses containing 40–50mol% Na2O, whereas glass transition temperatures reveals a minimum at the glasses with 30–40mol% Na2O. The 31P MAS NMR and Raman spectra of the first series show that with increasing Na2O content the ratio of structural units Q2/Q1 slowly increases and the Q2 phosphate units and BO4 units prevail in the structure of these glasses. In the second series of glasses Q1 diphosphate units together with BO4 and small number of BO3 units form structural network of glasses. The replacement of PbO by Na2O results in higher ionicity of bonding interactions between compensating cations and the anionic network. The lower cation field strength of Na+ ions results in the observed downfield shift of δ (31P) values in Na-rich glasses and narrower vibrational bands in their Raman spectra.