Lead Alumino Borate Glasses Research Articles

Enhanced visible green and 1.5 μm radiative emission of Er3+ ions in Li2O-PbO-Al2O3-B2O3 glasses for photonic applications

A series of Er3+ ions doped lithium lead alumino borate (LiPbAlB) glasses were synthesized via melt quench method and their structural, physical and optical properties were studied. Judd-Ofelt theory in correlation with the emission and absorption profiles was performed for the measurement of various radiative parameters for different transitions of Er3+ doped glasses. The as-prepared glasses show deep green (550 nm) as well as NIR (1532 nm) emission at 380 and 980 nm excitation wavelengths, respectively. The intensity of emission spectra increases with Er3+ ions concentration up to 1.5 mol% and beyond quenching is observed. The Dexter theory applied to the emission profiles reveals the interaction between Er3+ ions as dipole-dipole in nature. CIE color coordinates are found to fall in the green region of the visible spectrum. It is observed that 1.5 mol% of Er3+ ions concentration is optimum to exhibit the maximum quantum efficiency, branching ratios, gain bandwidth, emission cross-section, gain cross-section and aptly suitable for visible and NIR photonic applications.

Photon and neutron shielding characteristics of samarium doped lead alumino borate glasses containing barium, lithium and zinc oxides determined at medical diagnostic energies

Abstract In the present work, we studied the radiation shielding parameters such as mass attenuation coefficients, effective atomic number, half value layer, mean free path, macroscopic effective removal cross-sections and neutron transmission function for samarium doped lead alumino borate glasses containing barium, lithium and zinc oxides at medical diagnostic energies (between 20 and 150 keV) using MCNPX code. The results showed that the photon attenuation depends on the type of modifier used (i.e. ZnO, BaO or Li2O) and also, upon the energy of the photon. The higher mass attenuation coefficients were found for the glass containing BaO. The results also revealed that the glass containing Li2O has the maximum effective atomic number between 20 and 40 keV. In addition, some important neutron shielding parameters such as macroscopic effective removal cross-sections (ΣR) and neutron transmission function (N/N0) have been calculated for investigated glass samples.

Spectroscopic investigations on Dy3+ ions doped zinc lead alumino borate glasses for photonic device applications

This paper presents the structural, optical absorption, photoluminescence (PL) and decay spectral properties of Dy3+ ions doped zinc lead alumino borate (ZPAB) glasses to elucidate their possible usage in photonic devices such as w-LEDs and lasers. A broad hump shown by the XRD spectrum recorded for an un-doped ZPAB glass confirms its non-crystalline nature. The Judd-Ofelt (J-O) intensity parameter evaluated from the measured oscillator strengths of the absorption spectral features were used to estimate various radiative parameters and also to understand the nature of bonding between Dy3+ ions and oxygen ligands. Under 350 nm excitation, the as-prepared glasses are exhibiting two emission bands 4F9/2 → 6H15/2 (blue), and 4F9/2 → 6H13/2 (yellow) at 483 and 575 nm, respectively. From the PL spectra, the Y/B ratio values, CIE chromaticity color coordinates and color correlated temperature (CCT) were evaluated. The experimental lifetimes measured from the decay profiles are decreasing with increase in Dy3+ ions concentration in these glasses which may be attributed to the cross-relaxation and non-radiative multiphonon relaxation process. Decay profiles observed for higher concentration were well fitted to Inokuti-Hirayama (I-H) model to understand the energy transfer process and subsequent decrease in experimental lifetimes. The higher values of radiative parameters, emission cross-sections, quantum efficiency, optical gain and gain band width suggest the suitability of 0.5 mol% of Dy3+ ions in these ZPAB glasses for the photonic device application.

Spectral studies of Eu3+ doped lithium lead alumino borate glasses for visible photonic applications

Quaternary lithium lead alumino borate (LiPbAlB) glasses doped with different concentration of Eu3+ ions have been synthesized by melt quench technique and characterized by using XRD, Photoluminescence (PL), PL decay and CIE-chromaticity co-ordinates to understand their luminescence behavior. A broad hump observed in the XRD spectrum confirms glassy nature of the as-prepared un-doped glasses. By applying Judd-Ofelt (J-O) theory to the emission spectra, various radiative parameters for the prominent fluorescent levels of Eu3+ have been evaluated. An intense excitation peak observed at 393 nm matches well with the excitation wavelength of n-UV LED chip. The PL intensity increases up to 7 mol% of Eu3+ in LiPbAlB glasses and beyond quenching observed. The decay profiles observed for the prominent emission line 5D0 → 7F2 were well fitted to bi-exponential function and lifetime are decreasing with increase in Eu3+ ion concentration which may be due to efficient energy transfer between Eu3+-Eu3+ through cross relaxation channels. CIE chromaticity co-ordinates evaluated from the emission spectra, are found to be in red region of the visible spectrum. The enhanced color purity and quantum efficiency values were also evaluated from the emission spectral data. From the emission cross-sections, branching ratios, quantum efficiency, CIE coordinates and color purity, it was concluded that 7 mol% of Eu3+ ion concentration (glass C) is optimum in LiPbAlB glasses for visible red photonic device application.

Intense green emission from Tb3+ ions doped zinc lead alumino borate glasses for laser and w-LEDs applications

Zinc Lead Alumino Borate (ZPAB) glasses doped with varying concentrations of Terbium (Tb3+) ions have been prepared via melt quenching technique. Structural studies like XRD and FT-IR were performed to ascertain the amorphous nature and functional groups present in the as prepared glasses respectively. Photoluminescence (PL) properties of the as prepared glasses were investigated by performing excitation and emission spectral studies under 545 nm and 369 nm wavelengths respectively. Under n-UV excitation, these glasses exhibit four emission peaks due to transitions from the excited 5D4 level of Tb3+ to 7FJ (J = 3 to 6) ground level. Among all, the intense emission band was observed at 545 nm corresponding to the 5D4→7F5 transition and the emission intensity increases up to 1 mol%, beyond concentration quenching took place. The Dexter theory confirms the possibility of energy transfer via electric dipole-dipole interaction between Tb3+-Tb3+ ions. The CIE chromaticity coordinates and color purity were evaluated which falls in intense green region and close to European Broadcasting Union illuminant green. The PL decay studies were carried out to know the experimental lifetimes of the fluorescent levels of Tb3+ ions. The lifetime measured for 5D4→7F5 transition of the as prepared glasses decreasing with increase in Tb3+ ions concentration, may be due to efficient energy transfer between Tb3+-Tb3+ ions. The aforementioned results confirm potentiality of these glasses in solid state green laser and as a green component in tricolor w-LEDs.

Spectroscopic investigations of Nd3+ doped Lithium Lead Alumino Borate glasses for 1.06 μm laser applications

Neodymium doped lithium lead alumino borate glasses were synthesized with the molar composition 10Li2O10PbO(10-x) Al2O370B2O3x Nd2O3 (where, x = 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 mol %) via conventional melt quenching technique to understand their lasing potentialities using the absorption, emission and photoluminescence decay spectral measurements. The oscillator strengths measured from the absorption spectra were used to estimate the Judd-Ofelt intensity parameters using least square fitting procedure. The emission spectra recorded for the as-prepared glasses under investigation exhibit two emission transitions 4F3/2 → 4I11/2 (1063 nm) and 4F3/2 → 4I9/2 (1350 nm) for which radiative parameters have been evaluated. The emission intensity increases with increase in Nd3+ ion concentration up to 1 mol % and beyond concentration quenching took place. The decay profile shows single exponential nature for lower Nd3+ ion concentration and non-exponential for higher concentration. To elucidate the nature of energy transfer process, the non-exponential decay curves were well fitted to Inokuti-Hirayama model. The relatively higher values of emission cross-sections, branching ratios and quantum efficiency values obtained for 1.0 mol% of Nd3+ ions in LiPbAlB glass suggests it's aptness in generating lasing action at 1063 nm in NIR region.

Spectroscopic studies of single near ultraviolet pumped Tb3+ doped Lithium Lead Alumino Borate glasses for green lasers and tricolour w-LEDs

Terbium ions (Tb3+) doped Lithium Lead Alumino Borate (LiPbAlB) glasses with the chemical composition 10Li2O – 10PbO – (10-x) Al2O3 – 70B2O3 – xTb2O3 (where x = 0.5, 1.0, 1.5, 2.0 and 2.5 in mol%) were synthesized via melt quench method and characterized by absorption, photoluminescence (PL) and PL decay spectral measurements. The Judd-Ofelt (J-O) intensity parameters evaluated from the oscillator strength values are further used to evaluate the radiative parameters for the prominent fluorescent levels (5D4→7Fj) of Tb3+ ions. The intensity of all the emission bands increases up to 2mol% of Tb3+ and beyond concentration quenching took place. The decay profiles of 5D4 show single exponential for lower concentration and non-exponential for higher concentration resulting decrease in experimental lifetime (τexp) with increase in rare earth ion concentration. Such decrease in τexp and decay conversion from single to non-exponential has been attributed to the cross-relaxation processes and subsequent concentration quenching observed. The Inokuti-Hiryama (I-H) model applied to the decay spectral profiles confirms the energy transfer process between Tb3+-Tb3+ ions as dipole-dipole in nature. Higher values of stimulated emission cross-section, quantum efficiency, gain bandwidth and optical gain obtained for 5D4→7F5 transition of LiPbAlB glass with 2mol% of Tb3+ ions suggests its suitability for green lasers. The CIE-chromaticity co-ordinates, color purity (CP) and correlated color temperature (CCT) confirms the suitability of these glasses in tricolor w-LEDs.

Structural and luminescence properties of samarium doped lead alumino borate glasses

The study reports the effect of samarium concentration on the physical, structural and spectroscopic characteristics of samarium doped lead alumino borate glasses having composition 20PbO-(10-x)Al2O3-70B2O3-xSm2O3; x = 0.1, 0.5, 1.0 and 2.0 mol %. The glasses were fabricated by conventional melt-quenching technique and then characterized by XRD, FTIR, optical absorption and fluorescence spectra. X-ray diffraction studies confirmed the amorphous nature of the prepared glasses. FTIR spectra indicate the presence of BO3, BO4, AlO6 and a few other structural groups. Various physical properties such as density, molar volume, refractive index, rare earth ion concentration, boron-boron distance and polarizability etc. were determined using conventional methods and standard formulae. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. The value of Ω2 was found to be highest for glass with 1 mol% Sm2O3 and attributed to the asymmetry of the ligand field at the rare earth ion site and the rare earth oxygen (Sm-O) covalency. The calculated intensity parameters and fluorescence spectra were further used to predict the radiative transition probability (A), radiative lifetime (τR), branching ratio (βR), peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σ) for the characteristic 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 transitions of the Sm3+ ion. Concentration quenching was observed for 2 mol% concentration of Sm2O3 and ascribed to energy transfer through various cross-relaxation channels between Sm3+ ions. Reasonably high values of branching ratios and stimulated emission cross-section for the prepared glasses points towards their utility in the development of visible lasers emitting in the reddish-orange spectral region. However, the glass with 1 mol% Sm2O3 was found to show better radiative properties.

Photoluminescence and energy transfer studies of Dy3+ ions doped lithium lead alumino borate glasses for w-LED and laser applications

Lithium Lead Alumino Borate (LiPbAlB) glasses doped with Dy3+ ions with varying concentration were synthesized by using the melt quenching technique to understand their feasibility in solid state lighting and laser devices. From the absorption spectra, bonding parameters (δ) were evaluated to understand the nature of bonding between Dy3+ ions and its surrounding ligands. Judd-Ofelt intensity parameters estimated from the experimental oscillator strengths were used to evaluate various radiative parameters for the fluorescent levels of Dy3+ ions. From the decay curves, the experimental lifetimes were measured and coupled with the radiative lifetimes to evaluate the quantum efficiency. The decay profile changes from exponential to non-exponential with increase in Dy3+ ion concentration resulting decrease in experimental lifetimes. Inokuti-Hirayama model applied to the decay spectral profiles confirm dipole-dipole interaction responsible for their conversion from exponential to non-exponential. By exciting the glasses with different n-UV radiations, the CIE chromaticity coordinates and correlated color temperatures (CCT) were calculated to understand the utility of as-prepared glasses in cool white light generation. From the evaluated radiative parameters, CIE co-ordinates, CCT temperatures, emission cross-sections, quantum efficiency and confocal images, it was observed that LiPbAlB glass with 0.5mol% Dy3+ ions are more suitable for the development of w-LEDs and Lasers.

Spectroscopic studies of Sm3+ ions activated lithium lead alumino borate glasses for visible luminescent device applications

Photoluminescence (PL) characterization of Lithium Lead Alumino Borate (LiPbAlB) glasses doped with Sm3+ ions at varying concentrations have been studied by using absorption, excitation, emission, time resolved and confocal image measurements. From the absorption spectra, Judd-Ofelt (J-O) intensity parameters were evaluated and in turn used to estimate various radiative parameters for the fluorescent levels of Sm3+ ion doped LiPbAlB glasses. The PL spectra of Sm3+ ions exhibit three emission bands corresponding to the transitions 4G5/2 → 6H5/2, 6H7/2 and 6H9/2, for which the emission cross-sections and branching ratios were evaluated to know the potentialities of these materials as visible luminescent devices. The decay spectral profiles measured for 4G5/2 → 6H7/2 transition level were used to estimate quantum efficiency of the as-prepared glasses. The non-exponential decay curves observed for higher Sm3+ ion concentrations were well fitted to Inokuti-Hirayama model to understand the predominant energy transfer mechanism involved in the as-prepared glasses. CIE chromaticity coordinates and correlated color temperatures (CCT) were evaluated to understand the utility of the titled glasses in cool white light generation. The confocal images captured under 405 nm CW laser excitation show intense reddish-orange color. From the evaluated radiative parameters, emission cross-sections, quantum efficiency, CIE co-ordinates, CCT temperatures and confocal images, it was observed that LiPbAlB glass with 0.5 mol% Sm3+ ions are more suitable for w-LEDs and reddish-orange luminescent device applications.

Spectroscopic studies of Pr3+ doped lithium lead alumino borate glasses for visible reddish orange luminescent device applications

Abstract Lithium Lead Alumino Borate (LiPbAlB) glasses doped with Pr 3+ ions were prepared via melt quenching technique to study their luminescence behavior using absorption, excitation, photoluminescence (PL) and decay spectral studies. A broad hump observed in XRD confirms the amorphous nature of the as-prepared glass. The glass transition temperature (T g ) and thermal stability (ΔT) were measured from Differential Scanning Calorimetry (DSC). FT-IR and Raman studies were performed to understand the network functional groups involved in the host glass. Various radiative parameters for the prominent fluorescent levels of Pr 3+ were evaluated with in the frame work of Judd-Ofelt theory. PL and confocal images recorded under 445 nm Continuous Wave (CW) diode laser excitation were used to understand the visible emission characteristic features of the as-prepared glasses. The decay profiles of 1 D 2 → 3 H 4 show single exponential for lower concentration and non-exponential for higher concentration resulting decrease in experimental lifetime (τ exp ) with increase in concentration. Such decrease in τ exp and decay conversion from single to non-exponential with increase in rare earth ion concentration has been attributed to the cross-relaxation processes and subsequent concentration quenching observed. From the emission cross-sections, branching ratios, quantum efficiency, CIE coordinates and confocal images, it was concluded that 1 mol % Pr 3+ ion concentration is optimum in LiPbAlB glasses to develop visible reddish orange luminescent devices.

White light emission of Ce3+ sensitized Sm3+ doped lead alumino borate glasses

In present work, Ce3+ activated Sm3+ doped lead alumino borate glasses have been synthesized by melt quench method. Photoluminescence spectra were measured under different excitation wavelengths. The co-doped samples show enhanced Sm3+ ions emission at the cost of Ce3+ emission with the increasing Ce3+ ions concentration which shows that Ce3+ is acting as a sensitizer. This kind of luminescent behavior is discussed with respect to energy transfer process. The investigation based on excitation spectra and decay curves demonstrated that the energy transfer is nonradiative in nature taking place between Ce3+ and Sm3+ clusters. It is governed by dipole–dipole interactions as explained in terms of donor lifetime. The results showed that the white light has been achieved under excitation at 400nm when concentration of Ce3+ is in the range of 0.5–1.0mol%. An efficient energy transfer from Ce3+ to Sm3+ ions (up to around 42%) with decay times approaching 22ns has been observed at 400nm excitation. The UV–Vis absorption spectra shows an increase in intensity and a significant red-shift of the optical absorption edge with increasing rare earth ions concentration in lead alumino borate glass and the FTIR study depicts the conversion of trigonal BO3 units into more stable tetrahedral BO4 units.

Low frequency Raman investigations of lead borate and lead alumino borate glasses

Lead borate and lead alumino borate glasses in the systems xPbO·(100-x)B2O3 (0 ≤ x ≤ 75 mol%) and xPbO·(95-x)B2O3, 5Al2O3 (0 ≤ x ≤ 80 mol%), respectively, have been prepared and investigated by Raman spectroscopy. Using the Martin-Brenig model, structural correlation lengths were determinated from Boson peak positions of temperature reduced Raman spectra and transversal sound velocities. Vv polarized spectra contain information about the nature of the PbO component within the network.