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For the near-infrared emission, Er3+ and Er3+/Yb3+ co-activated borate based glass hosts were synthesized by the method of melting andquenching. The emission intensity was maximum for 0.5 mol% Er3+ singly activated glass in the near-infrared (NIR) region covering the telecommunication window. The 2 mol% of Yb3+ co-doping enhanced the emission gain cross-section of the glass by two times contrast to 0.5 mol% Er3+ loaded glass. This enhancement shifted to lower spectral regions when P increased from 0 to 1. The effect of Yb3+ loading on the gain cross-section of the Er3+ co-activated glasses was analyzed using the McCumber theory. The results showed that the 0.5Er2Yb glass has a flat gain in the range of 1460–1640 nm, this suggest a lower pump threshold is enough to perform the laser functioning of a 1530 nm band and optical window of telecommunication applications. [ABSTRACT FROM AUTHOR]

Sm3+ doped lithium zinc alumino borate glasses with composition 15ZnF 2 –12Li 2 CO 3 –10BaO–8Al 2 O 3 –(55-x)B 2 O 3 –xSm 2 O 3 where x = 0.1, 0.3, 0.5, 0.7 and 1.1 mol% were prepared by conventional melt quenching technique Their optical, physical, structural, mechanical and luminescence properties are investigated. UV–Vis-NIR absorption spectra showed all possible transitions of samarium ion in this glass matrix. Band gap values for all the glass samples were above 3 eV confirming the insulating nature for the glass. Densities, assessed using the Archimedes rule, were observed to be increasing with increasing samarium concentration. Increase in molar volume with addition of samarium content indicated that the extension of glass network is on account of the increase of number of Non-Bridging Oxygens created by network modifier samarium ions. Scanning Electron Microscopy (SEM) image showed a smooth surface for the synthezied glass. X-Ray Diffraction (XRD) technique was employed to verify the amorphous nature of the glasses. A Makishima and Mackenzie theoretical model gave acceptable approximation of elasticity constants viz. Young's modulus, shear modulus, bulk modulus and Poisson's ratio. The high Vickers hardness values evaluated with mechanical loads of 50, 100, 300, 500, 1000 g force, proved the stability of the glasses. Emission spectra showed a prominent transition 4G 5/2 → 6H 7/2 at 598 nm excited with 6H 5/2 → 4P 3/2 transition at 401 nm. Luminescence quenching effect was observed beyond 0.3 mol% Sm 2 O 3 addition. The chromaticity coordinates (x, y) clustered in the orange-red region, making these Sm3+ doped lithium zinc alumino borate glasses suitable candidate for applications in LEDs and solid-state lasers. • 15ZnF 2 –12Li 2 CO 3 –10BaO–8Al 2 O 3 –(55-x)B 2 O 3 –xSm 2 O 3 glasses were prepared by conventional melt quenching technique • Band gap values calculated using absorption spectra were above 3eV confirming the insulating nature of the glass. • Vickers hardness values evaluated with mechanical loads of 50 -1000 gram force proved the stability of the glasses. • Emission spectra showed luminescence quenching effect beyond 0.3mol% Sm 2 O 3 addition. • These glasses are suitable candidate for applications in LEDs and solid-state lasers. [ABSTRACT FROM AUTHOR]

The present study aims to examine the effects of beaming 7.5 MeV electron on europium-doped zinc sodium bismuth borate glasses (prepared through melt quench technique) and the resulting changes in structural and optical properties. The study also examines the structural depolymerization of irradiated glasses, analyzed using recorded Fourier transform infrared spectra. Absorbance spectra along with Tauc's plot were used to find the optical band gap of pristine and irradiated glasses. The study observes changes in photoluminescence spectra of irradiated Eu3+-doped glasses, monitored by exciting the samples at 394 nm. The study notes a decrease in emission intensity of Eu3+ ions observed from the emission spectra of electron beam treated glass samples. The thermally stimulated luminescence (TL) measurements of irradiated glasses resulted in intense glow peaks with increasing electron beam doses [4–50 kGy]. The TL glow curve exhibited two dissimilar peaks at distinct temperatures of 490 K and 610 K respectively. The obtained trap-depth (0.93 eV) using Chen's relation and intensity variation of first glow peak at 490 K as a function electron beam doses facilitates ZNBBE-4 glass for dosimetry applications. [ABSTRACT FROM AUTHOR]

• Covalent nature of bonding between Er3+ ions and their surrounding ligands was observed through bonding parameter and Judd-Ofelt parameters. • Hypersensitive transitions of Er3+ ion namely 4I 15/2 → 2H 11/2 &4I 15/2 → 4G 11/2 were interpreted through their higher oscillator strengths when compared to other transitions. Family of lithium zinc fluoroborate glasses with 15ZnF 2 -10BaO-8Al 2 O 3 –12Li 2 O-(55-x) B 2 O 3 -xEr 2 O 3 (x = 0.5, 0.7, 1.1, 1.3 and 1.5 mol%) composition were prepared by conventional melt-quench method. The glasses were characterized to study their structural, physical, optical and radiative properties. The amorphous characteristic of glass was noticed in X-Ray Diffraction pattern. A modification in structure was observed as density values increased with Er 2 O 3 content. UV–Vis–NIR transitions of Er3+ in the host matrix were identified through absorption spectra. Covalent nature of bonding between Er3+ ions and their surrounding ligands was observed through bonding parameter and Judd-Ofelt parameters. Red shift of the fundamental absorption edge in the absorption spectra and decreasing indirect and direct band gaps with increasing Er3+ concentration jointly confirmed the role of Er3+ ions as network modifier. Hypersensitive transitions of Er3+ ion namely 4I 15/2 → 2H 11/2 &4I 15/2 → 4G 11/2 were interpreted through their higher oscillator strengths when compared to other transitions. Emission spectra recorded at 980 nm excitation showed a peak corresponding to 4I 13/2 → 4I 15/2 NIR transition of erbium ion. Stimulated emission cross section of Er0.5 sample, gain bandwidth and Figure of Merit were found to be 16.79 × 10−21 cm2, 1225.83 × 10−28 cm3 and 37.36 × 10−24 cm2 s respectively. Photoluminescence decay curve of Er0.5 sample was well-fitted to single exponential first order function. The experimental decay lifetime τ exp for the 4I 13/2 level was measured to be 0.34 ms. The wide frequency range of FWHM (1.02–1.67 × 1013 Hz) and high values of radiative parameters make the glass a suitable candidate as optical amplifier and NIR laser material. [ABSTRACT FROM AUTHOR]

Abstract Authors aim to make a study on gamma (γ) rays effects over inorganic glassy materials. The Nd3+ content as well as high energetic induced radiation in the glass compositions resulted in the B O B bonds depolymerization creating NBOs (Non-Bridging Oxygens) in the matrices, interpreted through FTIR (Fourier Transform Infrared) spectra. The decrease in the T g , H r and H values obtained from Differential Scanning Calorimetry (DSC) thermograms and Vickers Microhardness Tester respectively, proved the changes in the glass structure after irradiation. The drastic decrease in the intensities of UV-VIS absorption and Photoluminescence (PL) emission peaks after irradiation, prompted the creation of defect points in the samples. The JO (Judd-Ofelt) theory was implemented to understand the asymmetric and covalent nature of the matrix and also to predict the radiative properties. The EPR (Electron Paramagnetic Resonance) spectra proved the presence of defects in the samples both pre and post irradiation. These changes were correlated with the Nd (Neodymium) and O (Oxygen) concentration ratios, studied through EDS (Energy-Dispersive X-ray spectroscopy), which showed decrease in the elemental composition post irradiation. The UV-VIS differential absorption spectra of the samples after γ irradiation depicts defects in the glass network with feasibility in valency change from Nd3+ to Nd2+ and decrease in Nd3+ ions number density after irradiation. Dipole-Dipole interactions within the ions were analyzed through lifetime decay measurement. 1.0 mol% of Nd3+ ions showed better radiation resistant nature and quality optical properties when compared to other samples both before and after γ rays interactions. Highlights • Generation of defects (color centers), through increase in disorderness (ΔE) and decreased E g values post irradiation. • Formation of NBOs after γ rays exposure with 150 kGy dose. • Covalent and asymmetrical ligand environment was analyzed in the lead fluoroborate network doped with Nd3+ ions. • The 4F 3/2 →4I 11/2 transition of the Nd4 glass sample, displayed technological traits. • These glasses exhibited a combination of morphological, structural, optical, thermal and mechanical properties that could be used in many optical and radiation shielding applications upto 180 °C temperature environment. [ABSTRACT FROM AUTHOR]

Abstract Interaction of 10ZnO-5Na 2 O-10Bi 2 O 3 –74.3B 2 O 3 -0.7Eu 2 O 3 glasses exposed to high dose gamma rays were investigated using XRD, FTIR, absorption, photoluminescence followed by thermally and optically stimulated luminescence studies. XRD analysis confirmed the amorphous nature of glasses post-irradiation. Variation in FTIR spectra revealed, structural deformation of borate groups as a result of high dose gamma irradiation. Enhanced glass absorbance and red shift in absorption edge were observed with the increase in gamma dose. Further, radiation-induced absorption coefficient confirmed the trapped charges in the forbidden energy gap supported by Tauc's plot and Urbach energy. Photoluminescence (PL) study demonstrated quenching of luminescence intensity at higher gamma doses. Lifetime of metastable 5D 0 state of Eu3+ ions were estimated by the decay curves and color purity was calculated using 1931 CIE chromaticity coordinates (x,y). Thermally and optically stimulated luminescence studies reassured the existence of charges in trap centers due to irradiation. TL glow curve exhibited two broad emission peaks with the corresponding temperature being at 490 K and 625 K. Distinct TL peaks of the material and their kinetic parameters (E, S, τ and b) were determined via Computerized Glow Curve Deconvolution (CGCD) method. Linear behaviour obtained through the dose response of the glass (0.25–3 kGy) proved their suitability for dosimetric application in the food irradiation zones in addition to red LEDs (< 1 kGy). Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract Present study reports the effects of varying concentrations of Pr3+ ions on the optical properties of 10ZnO-5Na 2 CO 3 -10Bi 2 O 3 -75-xB 2 O 3 -xPr 6 O 11 (x = 0.1–1 mol%) glasses prepared through melt-quench technique with an aim to achieve suitable optical gain medium for optoelectronic applications. Minimal changes in the measured density, X-Ray diffractogram and Fourier Transform Infrared spectra of the prepared samples confirmed the stability of the glass structure even after 1 mol% doping of the Pr3+. Bonding nature of Pr3+ ion with surrounding ligands and Judd-Oflet (J-O) intensity parameters of the glasses were determined using optical absorption spectra. The photoemission spectra exhibited reddish orange emission around 605 nm at 445 nm excitation. The calculated color chromaticity with x = 0.5847, y = 0.3701 coordinates for 0.1 mol% of the Pr3+ in the glasses suggests suitable optical gain medium for reddish orange LED applications. Metastable lifetimes of the Pr3+ ion were found-out by exponential fitting to the decay profiles. Lasing parameters of the glasses such as branching ratio, radiative transition probability and stimulated emission cross-section of 1D 2 →3H 4 transition were calculated using JO parameters indicating 0.1 mol% Pr3+-doped glasses suitable for 605 nm solid-state laser applications. The mechanism of energy transfer is determined by applying the Inokuti-Hirayama model and was found to involve a dipole-dipole type of interactions. Thermoluminescence (TL) glow curves of the gamma-ray treated 0.1 mol% Pr3+-doped zinc sodium bismuth borate glasses were de-convoluted using Computerized Glow Curve Deconvolution method to evaluate the energy storage properties of the glasses. The intensity variation of the TL component peak (CP2) at 500 K showed linear behavior up to 3 kG y suggesting application in high dose measurements. Graphical abstract Image 1 Highlights • Praseodymium doped zinc sodium bismuth borate glasses were prepared by melt quench technique. • The negative value of the bonding parameter revealed the ionic bonding between the Pr3+ ions with surrounding oxygen. • Hypersensitive transitions 3H 4 →3F 3 and 3H 4 →3P 2 of Pr3+ ions exhibited maximum values of oscillator strength values. • JO intensity parameters of 0.1 mol% Pr3+ doped glass showed very high rigidity and symmetry around Pr3+ ions. • CIE chromaticity diagram confirmed reddish orange color emission of these glasses under the 445 nm excitation. • Deconvoluted TL curve of fitted with 5 peaks and peak at 505 K showed linear dose response up-to 3 kGy gamma ray. [ABSTRACT FROM AUTHOR]

Zinc sodium bismuth borate (ZNBB) glasses doped with different concentrations of europium were prepared by conventional melt quenching method and characterized through the measurements of density, refractive index, X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectra, optical absorption, luminescence and radiative lifetimes. FTIR spectra showed seven characteristic peaks of bismuth and borate functional groups in the range of 400–1600 cm −1 . The optical band gap and bonding parameters have been calculated from absorption spectra. Photoluminescence spectra recorded in the visible region with 394 nm excitation are used to calculate the Judd-Ofelt (JO) intensity parameters (Ω 2 and Ω 4 ). The JO intensity parameters have been used to calculate the radiative parameters such as branching ratio (β), stimulated emission cross-section ( σ se ), transition probability (A) for the fluorescent level of 5 D 0 → 7 F 2 . Decay rates through single exponential are used to calculate the lifetime (τ m ) of the meta-stable state 5 D 0 of (Eu 3+ ion) these glasses. The radiative parameters measured for all these glasses show 0.7 mol% europium doped zinc sodium bismuth borate glass 5 D 0 → 7 F 2 transition has the potential for red laser applications. The quality of the colour emitted by the present glasses are estimated quantitatively by CIE chromaticity coordinates, which confirms the suitability of these glasses as a red emitting material for field emission technologies and LEDs. [ABSTRACT FROM AUTHOR]

The present study explores a new borate family glasses based on 10ZnO-5NaO-10BiO-(75 − x) BO- xEuO ( x = 0, 0.1, 0.5, 1, 1.5, 2, 3 mol%) composition, synthesized by rapid melt quench technique. Prepared glasses were subjected to the density and refractive index measurements and their values were used to calculate other physical properties of the glass matrix as a function of Eu concentration. XRD confirmed amorphous nature of the glasses. FTIR spectra in the absorption mode were recorded in the 400-4000 cm region to identify different functional groups in the glass matrix. Deconvoluted FTIR spectra showed increase in BO units with rise in europium content which confirmed the 'network strengthener' role of europium ions by creating bridging oxygens (BOs). Optical properties were investigated for their luminescence behavior through various spectroscopic techniques such as UV-Vis-NIR absorption, excitation, emission, decay profiles, and color measurements at room temperature. Lasing properties of the glasses like total radiative life time, branching ratio, emission cross section, and optical gain were obtained from the calculated Judd-Ofelt (Ω,Ω) intensity parameters. From the measured values of emission, cross sections, branching ratios, life times, strong photoluminescence features, and CIE chromaticity coordinates, 0.5 mol% of Eu ions doped ZnNaBiB glasses showed optimum performance and are potential candidate for red light generation at 613 nm. [ABSTRACT FROM AUTHOR]

In this study, highly Eu3+ doped (up to 5 mol%) 10ZnO 40Bi 2 O 3 50B 2 O 3 glasses were prepared by melt quench process. The excitation and emission results of the prepared glasses were recorded in the visible region. The Judd Ofelt intensity and CIE chromaticity parameters of the glasses were calculated and discussed. The nonlinear optical properties of glasses were studied at a pumping wavelength of 532 nm under a nanosecond regime utilizing the sensitive Z scan technique. We investigated the linear attenuation coefficient (LAC) for the prepared glasses for energies ranging from 0.296 to 1.458 MeV. According to the Z eff results, 10ZnO 40Bi 2 O 3 45B 2 O 3 5Eu 2 O 3 exhibited good attenuation properties among the fabricated samples. [ABSTRACT FROM AUTHOR]

The present work focuses on Dy3+ doped 20SiO 2 -(20-x) B 2 O 3 –10Al 2 O 3 –10ZnO–30NaF–10ZnF 2 glass ceramics (GCs), a white light emitting material prepared by conventional melt-quenching technique and thermal treatment. The glass ceramics exhibited good morphological evolution of α-Na 3 AlF 6 crystals at elevated temperatures. Bandgap values are obtained lower for glass ceramics compared to precursor glass which almost tends to come closer to the bandgap value of semiconductor. A good photoluminescence (PL) performance is monitored in glass ceramics with increased emission intensity having two dominant peaks at 482 and 575 nm. Stimulated emission cross section in glass ceramics obtained higher for the level 6H 13/2 characterize their significance in laser active media. Quantum efficiency is achieved greater than 80% for glass ceramics ensures their appropriateness for LEDs application. In particular, the yellow to blue intensity, colour coordinates and colour correlated temperature have been evaluated for glass ceramics. With the formation of α-Na 3 AlF 6 crystalline phase surrounded by Dy3+ ions, the PL properties in glass ceramics is enhanced notably. The obtained glass ceramics should be acknowledged as a promising material in white-LEDs and optoelectronic devices applications. [Display omitted] • Glass ceramics containing α-Na 3 AlF 6 crystalline phase is obtained through different annealing temperatures. • Morphological analysis shows the evolution of small crystals in the glass ceramics. • Judd-Ofelt calculation reveals the covalency character of both glass and glass ceramics. • Emission intensity and quantum efficiency of glass ceramics is improved with formation of α-Na 3 AlF 6 crystalline phase. • The prepared glass ceramics showed bright white light emissions. [ABSTRACT FROM AUTHOR]

Gamma irradiation effect on absorption, photoluminescence (PL), and nonlinear optical (NLO) features of Eu3+ doped heavy metal borate glasses was studied and elucidated in detail. With blue light excitation, the emission intensity of Eu3+ doped glass was monitored with respect to irradiated dose. The PL intensity of the glasses was reduced with a raise in gamma dose rate because of the formation of colour centres. The quality of the emission colour of the pre- and post-irradiated glasses was analysed using 1931 CIE system. The Nonlinear Optical (NLO) features were examined by the Z–scan technique in the near–infrared spectral region and using femtosecond pulse excitation. The NLO attributes were enhanced with increase gamma irradiation dose. These enhancements are ascribed to the development of defects and non–bridging oxygens when irradiated with gamma radiation. The enhancement of NLO coefficients with gamma irradiation dose suggest the high dose irradiated glasses are useful for photonic device applications, particularly for optical limiters. • Influence of gamma irradiation on the PL and NLO properties of Eu3+ doped heavy metal borate glasses was investigated. • PL properties were evaluated under blue light excitation. • PL intensity of the glasses was reduced with a raise in gamma dose rate. • NLO attributes were enhanced with increase gamma irradiation dose. [ABSTRACT FROM AUTHOR]

Herein, heavy metal borate glasses activated with different concertation of Eu 2 O 3 were prepared via the melt quench method. The Eu3+ concentration effect on photoluminescence (PL) properties of prepared glasses was investigated and discussed in detail to understand their utility in solid-state lighting and other photonic applications. The present work explains the suitability of two heavy metal oxides such as PbO and Bi 2 O 3 for Eu 2 O 3 doping to develop the glassy materials for photonic applications. The PL intensity was increased with an increase in Eu3+ content in PbO framed borate glasses while in Bi 2 O 3 containing borate glasses the PL intensity was decreased at higher concentration due to concentration quenching. The Judd–Ofelt parameters and the radiative properties suggest the heavy metal borate glass hosts activated with 1 mol % of Eu3+ were potential materials for red light-emitting devices under blue light excitations. The Lifetime values of the PbO framed glasses were greater compared to Bi 2 O 3 framed borate glasses which suggest the borate glass host containing high PbO content is more precisely suitable than Bi 2 O 3 containing borate glass for solid-state lighting applications under blue light excitation. Image 1 • Photoluminescence properties of Eu3+ ions in PbO and Bi 2 O 3 containing borate glasses were investigated. • The PbO containing glasses activated with 1 mol % of Eu 2 O 3 were exhibited improved spectroscopic and luminescence properties. • Studies suggest the PbO containing glasses are beneficial for solid state lighting application under blue light excitation. [ABSTRACT FROM AUTHOR]

• Effect of Eu2O3 on PL properties was investigated and confirmed the optimize concentration. • Efficacy of Ag NPs on PL properties of optimized Eu2O3 activated glasses were investigated. • Role of Ag NPs on enhancing the PL properties has been underlined. • The 0.6 mol% of AgNO3 embedded glasses were beneficial for the optoelectronic devices. Efficacy of silver nanoparticles on photoluminescence properties on optimized Eu 2 O 3 doped borate glasses has been studied and discussed in detail. The presence of homogeneously distributed and spherically shaped Ag nanoparticles was confirmed by electron microscopic images. With increase of AgNO 3 concentration the photoluminescence intensity of Eu3+ transitions improved up to 0.6 mol% and subsequently quenched at 0.8 mol% of AgNO 3. The enhancement in photoluminescence properties observed as the AgNO 3 concentration raised to higher level was ascribed to local field effect and transmit of energy from Ag nanoparticles to the tri–positive europium ions. While the reduction in photoluminescence properties at higher doping level of AgNO 3 was attributed to reverse transmit of energy from tri–valent europium ions to Ag nanoparticles. Other mechanisms liable for the attenuation in photoluminescence properties are also highlighted. The energy transfer from Eu3+ ions to Ag0 nanoparticles was responsible for the reduction in radiative lifetime magnitudes. The studies suggest the glass sample containing 0.6 mol% of AgNO 3 (i.e. SNBEuAg0.6) beneficial for optoelectronic and photonic applications. [ABSTRACT FROM AUTHOR]

• Photoluminescence properties were investigated under blue light excitations. • The studies recommend high Eu3+ activated glasses are beneficial for solid state lighting applications. • Optical nonlinearities and optical limiting properties were investigated using Z-scan. • Non–linear optical and optical limiting investigations suggest the glasses are beneficial for optical limiting applications. Tri–positive rare earth ions activated alkali heavy metal borate glasses were designed and synthesised using melt–quenching process. Photoluminescence (PL), nonlinear optical (NLO), and optical limiting (OL) attributes of titled glasses have been systematically investigated in order to understand the efficacy of tri–valent europium ions and the obtained results are discussed in detail. The PL attributes were assessed with the blue light pumping. The NLO and OL features were evaluated in 700–1000 nm spectral region using femtosecond laser pulses. The two–photon absorption and nonlinear refractive index coefficients were found to be increased with elevation of Eu 2 O 3 content to higher doping whereas the OL threshold factors exhibited an opposite behaviour. The PL and Judd–Ofelt analysis revealed the glass matrices containing high concertation of tri–valent europium ions are more useful for red lighting applications when excited with blue light. NLO and OL results suggest the strong Eu3+ containing glasses are ideal materials for designing optical limiters of high power to work in near infrared region with femtosecond pulses. [ABSTRACT FROM AUTHOR]

Influence of Heavy Metal Oxides (HMOs: PbO and Bi 2 O 3) on structural and photoluminescence (PL) properties Eu3+ activated lanthanum borate glasses has been analyzed and discussed in thoroughly here. When the PbO is loaded more and more in the glass system, the luminesce intensity and lifetime values of 5D 0 → 7F 2 transition of Eu3+ were improved for the excitation at 464 nm due to enhanced covalency of Eu–O bonds arose from the dual function of lead oxide in the structure of PbO varied glasses. The betterment in luminescence features are also attributed to the decrease of effective network phonon energy occurred because of the incorporation of lead oxide in the glass composition. On the other hand, the luminesce (emission intensity and lifetime values of 614 nm emission of Eu3+ under 464 nm excitation) results are completely upending as the Bi 2 O 3 content increased gradually in the glass matrix. This reduction in luminescence properties are ascribed to the decrease of covalency of Eu–O and thus crystal field in the vicinity of Eu3+ site. The reduction of covalent character of Eu–O is due to two facts, one being the newly generated NBOs owing to the generation of BiO 6 units with the incorporation of Bi 2 O 3 in the glass matrix and the second, the development of Bi–O–Bi and Bi–O–B linkages. The luminescence and spectroscopic attributes evidently reveal the lead varied borate glass hosts are more beneficial than Bi 2 O 3 varied borate glass hosts for optoelectronic applications. • Influence of PbO and Bi 2 O 3 on photoluminescence and structural properties of Eu3+ activated glasses has been investigated. • The structure–photoluminescence property correlation has been highlighted. • Results suggest the PbO containing glasses are more beneficial for solid–state and laser lighting applications. [ABSTRACT FROM AUTHOR]