Melt quenched borosilicate glasses with fixed Sr2+ ions Strontium alumino-borosilicate doped with CuO (SABSC) glasses with the composition 35SrO–(5–x)Al₂O₃–20B₂O₃–40SiO₂:xCuO (0.1 ≤ x ≤ 0.8 mol SABSC glasses were synthesized by melt quench process. The emission properties of Cu+ and Cu2+ ions were studied with 290 nm pumping. Suitable for optical devices due to narrow intense emission band at 575 nm. CIE coordinates from PL spectra provided scope for photonic applications.

Tailoring the wavelength of lanthanide sources with transition metal oxides as luminescent probe for luminescence and NIR imaging is still challenging in medical field. In this context, the role of copper ions was analyzed in tailoring the wavelength of emission in melt quenched series of copper doped holmium lead Boro phosphate glasses. To confirm the amorphous nature, the series of glasses were characterized by XRD. To realize the symmetrical and asymmetrical vibrations in glasses to support luminescence, the FTIR studies were carried out for the samples. The traces of DTA demonstrated thermal stability and the XRD analyses demonstrated the nature of all the glasses as amorphous character. The ground state orbital is d(xy)(2)(B-2(1g)) for Cu2+, and the ligand environment around Cu2+ is made up of tetragonally distorted octahedral sites, according to the Spin-Hamiltonian parameters (SHP) of the EPR spectra. The Cu2+-Ho3+ ions co-doped glass's absorption spectra revealed surface plasmon resonance (SPR) for Cu2+ ions at about 537 nm. The B-2(1g) -> B-2(2g) transition is attributed to the distinctive broad bands observed in the optical absorption spectra. Ho3+ ions are responsible for ten absorption transitions in the visible-NIR regions of the optical absorption spectrum. Furthermore, the octahedral absorption transition between B-2(1g) (D) -> B-2(2g) (D) of the Cu2+ ions was discovered to be responsible for a strong transition in the visible spectrum at about 864 nm. The luminescence spectra of glasses containing Cu ions have shown a peak at around 765 nm, owing to octahedral lattice of Cu2+ ions. Among all the emission transitions of Ho3+ ions, the S-5(2) + F-5(4) -> I-5(7) (763 nm) transition intensity was enhanced when compared to that of Cu2+ ions free glass, with a progressive increase in CuO mol%. The data analysis suggests that there is an increase in the energy transfer from octahedral Cu2+ ions to Ho3+ ions (Cu2+ -> Ho3+) at mol% of 0.5 (HC5). The time decay curves at 763 nm also supported the proposed energy transfer mechanism. Hence the synthesized glass HC5 can be a potential candidate for 763 nm light source for NIR imaging.

Na2O-SiO2-ZrO2 glasses doped with V2O5 were prepared with the melt quenching method, and were then analyzed using various techniques; in particular, with X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and optical absorption, photoluminescence, electron spin resonance (ESR), and Fourier transform infrared (FT-IR) transmission spectroscopy. The obtained results indicate that, in the studied glasses, vanadyl complexes tend to undergo a reduction from V5+ ions to V4+ ions. XRD and EDS data suggest that the glasses have amorphous nature with randomly distributed grains within the glass matrix. The optical absorption spectra show two transitions: 2B2g→2B1g and 2B2g→2Eg. The photoluminescence spectra exhibit a broad band from 750-900 nm, indicating the 2E→2T2 transition of vanadyl ions. The energies of the band gaps decreased gradually with increasing V2O5 content. The ESR spectra suggest that V4+ ions are situated in octahedral sites with tetragonal compression. The FT-IR spectra confirm the presence of various structural units within the glasses. Finally, the dielectric properties of the glasses were also measured, showing that the dielectric constant (ε′) and the loss tangent (tan δ) increase as the content of vanadium ions increases, indicating presence of V4+ ions within the glass matrix.

In this work, the conventional melt quenching approach is used to synthesize the Pr3+ doped NaF-Bi2O3-B2O3-SiO2 (NBBS) glasses. The influence of Pr3+ ions on their spectroscopic and structural characteristics in glass network is investigated. The amorphous nature of the samples has been amply verified by X-ray diffraction patterns. FTIR spectra show distinct basic vibrational bands in borate and silicate structural components (in the range from 500 to 3750 cm− 1). In the UV-visible range, the absorption spectra showed four Pr3+ ion absorption bands. Furthermore, in the absorption spectra, four Pr3+ ion absorption bands were observed in the NIR regions (1300–2470 nm). While utilizing Tauc plots to assess optical bandgap (Eg), it is observed that as the concentration of Pr3+ increases from 0 mol

A series of aminated PMMA/GO polymer nanocomposite (PNG) were synthesized by solution mixing in two step process. The synthesized PNG samples were analysed using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning Electron Microscope (SEM), energy dispersive X-ray analysis (EDAX), Thermo-gravimetric, differential thermal analysis (TG-DTA), UV–Visible spectroscopy (UV-Vis) and impedance spectroscopy. The X-ray diffraction (XRD) data indicated the existence of crystalline nature in PMMA and the reduction of graphene oxide (GO) which is also confirmed by TGA and DTA results. The interaction between graphene oxide nanoparticles and the functionalized polymer matrix has been validated using FTIR investigations. The SEM and EDAX measurements demonstrated the homogeneous dispersion of graphene oxide (GO) over the surface of the produced samples. The UV-Vis spectroscopy analysis revealed that the optical energy gap values of nano composites decrease as the amount of graphene oxide nanoparticles increases. All samples exhibited higher relative permittivity at low frequencies which is a key factor for high energy density. As the concentration of GO increases, the maximum peak of dielectric loss tangent also shifted to higher frequency due to increase in interfaces. The β relaxation is dominant in non-polar PMMA due to the functionalisation and dispersion of GO. The AC conductivity values increased with increase in concentration of GO. The single semicircle in plot from impedance spectroscopy and the drop in bulk resistance values of PNG samples made them as a good material for energy storage devices like supercapacitors.

These days green laser is preferred as a flexible tool for welding direct bonded copper plates used in power electronics to improve electrification of automotive industry. As terbium is known for green emission, Tb3+ doped strontium zinc borate glasses are melt quenched. The broad hump in x-ray diffraction spectra revealed the amorphous nature. Structural modifications and stability of glasses was shown from fourier transform infrared spectra and differential thermal analysis traces. The Judd-Ofelt intensity parameters are calculated to realize the ligand environment among Tb3+ ions in host glass. The Tb3+ concentration dependent fluorescence properties in visible region and the non-radiative decay rates of D-5(4)-> F-7(5) transition due to resonant energy transfer apart from intensity quenching of D-5(3)-> F-7(5) transition in green region was studied. A strong peak registered at 542 nm for the transition D-5(4)-> F-7(5) in the green region of emission spectra under the excitation of 378 nm. The radiative properties for the prominent luminescent transitions D-4(5)-> F-7(J (J=6,5,4,3)) of Tb3+ ions are measured using Judd-Ofelt parameters. The values sigma(e,) beta(R,)eta (%), life- time decay and CIE co-ordinates for the transition D-5(4)-> F-7(5) confirms that this transition is appropriate for potential green laser. (C) 2022 Elsevier B.V. All rights reserved.

A series of single (Sm3+, Eu3+) and co-doped (Sm3+- Eu3+) Yttrium alumino bismuth borosilicate (YABiBS) glasses have been prepared by basic melting quench method and the emission properties of synthesized glasses were investigated. To analyze the optical and energy transfer mechanism of these glasses the characterizations viz, absorption and luminescence are done. The absorption spectral data is used to observe the electronic band structure by direct and indirect optical band gaps. Bonding Parameters ((beta) over bar,delta) were evaluated to explain the ionic (or) covalent nature of the metal-ligand bonds in the present glass network. Near ultraviolet (n-UV) and blue excitations such as 392 nm, 400 nm, 457 nm, and 488 nm are used to record the emissions of single (Sm3+) and co-doped (Sm3+-Eu3+) glasses to achieve the tuneable emissions. Sm3+ ions show the reddish-orange emission mainly through (4)G(5/2) -> H-6(7/2) (597 nm) and Eu3+ ions show the intense red emission of transition D-5(0) -> F-7(2) (612 nm). For the Sm3+-Eu3+ glasses by using different excitations, we will achieve the emission changes from orange to reddish-orange and then to red. Decay curves were analysed to know the process of interaction involved in the energy transfer among co-doped RE3+ ions. CIE coordinates and CCT values for all the prepared glasses by various excitations were calculated.

The Tm3+/Ho3+ co-doped sodium-sulfo lead phosphate glasses (GTmHo-x) were synthesized by melt-quenching technique. The basic characterizations like XRD, FTIR are performed to analyse the structural behaviour in the glasses. The optical absorption studies were carried out. The NIR and MIR photoluminescence (PL) spectra were recorded at 797 nm excitation for GTmHo-x (x = 0.3, 0.6, 0.9, 1.2 and 1.2 mol%) glasses. The properties of emission bands at 1.4 mu m, 1.8 mu m and 2.0 mu m corresponding to Tm3+:H-3(4), Tm3+:F-3(4), and Ho3+:I-5(7) transitions respectively, were studied. The NIR, Tm3+:H-3(4) (1.4 mu m) emissions with broad full width half-maxima for single Tm3+ (121 nm) and Tm3+/Ho3+ co-doped (126 nm) were noticed in sodium-sulfo lead phosphate glasses. The highest PL emission intensity was obtained for GTmHo-0.9 glass. Moreover, the intensities of the Tm3+:1.8 mu m and Ho3+:2.0 mu m exhibited reverse trend in GTmHo-x glasses. To analyse the fluorescence behaviour, the energy transfer mechanism from various levels of Tm3+ -> Ho3+ ions have been figured out and discussed. Further, the stimulated emission cross-section of Tm3+:1.8 mu m and Ho3+:2.0 mu m in single Tm3+ and Tm3+/Ho3+ co-doped glasses were calculated. The highest emission intensity, gain coefficient and emission cross-section of 0.9 mol % Ho3+ ion concentration suggests that GTmHo-0.9 glass is the favourable glass to perform highest MIR 2.0 mu m emission. In short, the prepared GTmHo-x glasses might be a promising material for S-band (1.4 mu m) amplifier in telecommunications and MIR (2.0 mu m) solid-state lasers.

Switching of three trivalent ions in a host glass may tailor the emission properties. In this direction, singly Ce3+, Tb3+, Sm3+ doped and Ce3+/Tb3+/Sm3+ tri-doped barium gallium borosilicate (CTS) glasses were synthesized and spectroscopic studies viz., optical absorption and photoluminescence were performed to investigate the emission properties. The amorphous nature, thermal stability and functional groups in the glass are identified by x-ray diffraction, differential thermal analysis (DTA), FTIR spectra, respectively. The optical absorption (OA) spectra of triply doped glasses have shown Ce(3+)ion transition 4f (F-2(J)) -> 5d ((2)A(1g)) at 416 nm, four bands from F-7(6) ground state of Tb3+ ions and nine bands from H-6(5/2) ground state in the visible and NIR regions of Sm3+ ions. The evaluated values of optical band gap (E-g) have shown inverse proportionality with Ce3+ ion concentration in Tauc plots and correlated with optical basicity of glasses. The photo luminescence (PL) spectra of Ce3+/Tb3+/Sm3+ tri-doped Ba Ga B Si glass with 0.6 mol % Ce3+ ions (0.6 CTS) have shown maximum emission when excited at 350 nm. The energy transfer (ET) mechanism with dipole-dipole as main interaction between Ce3+ -> (Tb3+ -> Sm3+) ions is evident from all non-exponential time decay curves fitted with I-H (Inokuti-Hirayama) model. The ET efficiency 'eta' is varied from 36.8 to 57.6 %. The colour chromaticity coordinates at 350 nm excitation and emission covered blue (Ce), reddish orange (Sm) and green (Tb) regions. The CCT values of glasses are varying from 1636 K to 6412 K provides the scope for white LED applications.

The properties of glass materials with CuO are suitable for both optical and photovoltaic applications. The role of CuO hinges on the structural properties of glass network. The structural and luminescence properties of melt quenched strontium bismuth borosilicate glasses containing Sm2O3 with varying amounts of CuO (referred as N: SmCu) were studied. Two valence states of Cu ions are possible due to more amount of silica in glass. The amorphous nature of glass was confirmed by XRD and thermal parameters were explained through DTA curves. FTIR spectrum indicated the variation of asymmetric vibrations of SiO4 units with change in SrO and CuO concentration which influence the valence state of Cu2+. The absorption spectra have shown peaks due to 3 d(10)-> 3 d(9) 4s(1) transition of Cu+ ions, H-6(5/2) -> P-6(3/2) transition of Sm3+ and broad B-2(1g)-> B-2(2g) transitions of Cu2+ ions. The NIR region has peaks of Sm3+ ions. The Photo Luminescence (PL) spectra of N: SmCu glasses exhibited cyan bluish emission at 485 nm followed by intense emission peaks of Sm3+ at 312 nm excitation. The emission of N: SmCu10 and N: SmCu12 glasses are quenched due to Cu2+ ions. Moreover, maximum range of emission is exhibited by 'N: SmCu8' glass. The shortening of life time decay observed in 'N: SmCu' glasses was inferred to the process of energy transfer. The profiles of life time decay curves are fitted with the help of bi-exponential function. The CIE and CCT values of all glasses are calculated. The white light emission is quite possible in N: SmCu10 glass and the remaining glasses covered Orange - red regions with CCT values ranging from 1892 K-2351 K.

Over the past decades, phosphate glasses show ample advantages in laser technology because of their excellent optical properties like a low glass transition temperature, low phonon energy, large infrared transmission window, and high gain density. The inclusion of lead and alkali earth metals to these phosphate glasses also improves the chemical durability of glasses, which have more advantages in smart cards, medical applications, and micro-batteries. The optimum environment for chemical durability and incorporating rare earth ions can be achieved by the interaction between sulphate and phosphate ions. Moreover, phosphate glasses mixed with alkali sulphate provides scope for micro battery applications. The presence of network modifiers like Pb2+, Zn2+ in phosphate glasses introduces structural modifications and increases the number of non-bridging oxygens (NBOs) in glass network. The metal oxides like PbO, Bi2O3 makes phosphate glass suitable for rare earth ion incorporation by softening the glass and provides better distribution by controlling the formation of clusters. The wide variety of rare earth ions in the phosphate glasses leads to wide range of applications in optoelectronic devices. To overcome the difficulty associated with lack of a useful absorption band at 980 nm of Ho3+ ion (easy excitation by commercial laser diode (LD)), rare earth ions such as Tm3+, Yb3+, and Er3+ can be introduced. Especially, among them, Er3+ exhibit strong absorption at 980 nm. Due to the narrower energy gap between Er3+: 4I13/2 and Ho3+: 5I7 states, the emission of Ho3+ ions can be enhanced by addition of Er3+. So, the Er3+/Ho3+ co-doped glasses have promising applications in mid-infrared (MIR) laser applications with 980 nm LD. In view of this, the set of the Er3+/Ho3+ co-doped sodium-sulfo lead phosphate glasses was prepared with the molar composition of (20-x-y) Na2SO4-20PbO-60P2O5-xEr2O3-yHo2O3 (x=0.5, y= 0.2, 0.4, 0.6, 0.8, 1.0 mol %) named as GEH-y glass and coded as GExHy. To explore various possible applications, all prepared glasses are characterised by EDS, XRD, FTIR, absorption, photoluminescence and lifetime profiles. All results are computed and few of them are compared with other glasses. We present results focused on both mid infrared and visible emission properties of Er3+/Ho3+ions in sodium-sulfo lead phosphate (GExHy) glasses. These materials exhibit simultaneously DC (down-conversion) and UC (up-conversion) photoluminescence (PL) by excitation at 379 nm and 980 nm. The favourable concentration of Ho2O3 was estimated from the analysis of NIR PL spectra for Ho3+: 2.0 mm and Er3+: 1.5 mm. In GExHy glasses, the increase in intensity near 2.0 mm with decrease in intensity at 1.5 mm infers to energy transfer process between Er3+ and Ho3+ ions. Under lexc= 379 nm the Er3+ ions are pumped to the 4G11/2 excited state and depopulate {via multi phonon relaxation MPR1} at lower 4S3/2, 2H11/2, and 4F9/2 levels and then relaxed to the 4I15/2 ground state by emitting weak and strong green emission bands along with weak red emission related to 4S3/2→4I15/2 (522 nm), 2H11/2→4I15/2 (544 nm), and 4F9/2→4I15/2 (657 nm) transitions, respectively. The up-conversion energy transfer (ET) analysis with 980 nm LD excitation, undergoes the following mechanism: Ground state absorption (GSA) : Er: 4I15/2 + hν → Er: 4I11/2 Excited State Absorption (ESA1) : Er: 4I11/2+ hν → Er: 4F7/2 Excited State Absorption (ESA2) : Er: 4I13/2 +hν → Er: 4F9/2 CR1 (Cross Relaxation) : Er: 4I11/2+Ho: 5I6→ Er: 4I15/2+Ho: 5F4 CR2 (Cross Relaxation) : Er: 4I13/2+Ho: 5I6→ Er: 4I15/2+Ho: 5F5 ET1: Er: 2S3/2+Ho: 5I8→ Er: 4I15/2+Ho: 5S2+5F4 ⇒ Ho: 5S2+5F4 → 5I8 (545 nm) ET2 : Er: 4F9/2+Ho: 5I8→ Er: 4I15/2+Ho: 5F5 ⇒ Ho: 5F5→5I8 (659 nm) MPR2: Ho: 5S2+5F4 → 5F5 ET3: Er: 4I11/2+Ho: 5I8→ Er: 4I15/2+Ho: 5I6 ⇒ Er: 4I13/2 → 4I15/2 (1554 nm) ET4: Er: 4I13/2+Ho: 5I8→ Er:4I15/2+Ho Fig. 1 Schematic energy level diagram of GE0.5H0.8 glass. The maximum energy transfer efficiency of GExHy samples is 75.5% and with the increase of Ho3+ ions, the lifetime decay has been reduced from 5.06 ms to 1.24 ms. The absorption and stimulated emission cross-sections of Er3+:1.5 mm and Ho3+: 2.0 mm were calculated. Moreover, the FWHM × σemi was estimated for Ho3+:5I7→5I8 transition to estimate the probable MIR laser emission. The CIE color coordinates were estimated from both DC and UC PL spectra. All the results indicated that the prepared GExHy glasses have promising material applications in mid-infrared solid-state lasers and telecommunications. In addition, efficient green and red emission makes these glasses attractive for the phosphor applications. Figure 1

BACKGROUND:The accurate ranking of analogs of lead molecules with respect to their estimated binding free energies to drug targets remains highly challenging in molecular docking due to small relative differences in their free energy values.METHODS:Free energy perturbation (FEP) method, which provides the most accurate relative binding free energy values were earlier used to calculate free energies of many ligands for several important drug targets including Fructose-1,6-BisphosPhatase (FBPase). The availability of abundant structural and experimental binding affinity data for FBPase inhibitors provided an ideal system to evaluate four widely used docking programs, AutoDock, Glide, GOLD and SurflexDock, distinct from earlier comparative evaluation studies.RESULTS:The analyses suggested that, considering various parameters such as docking pose, scoring and ranking accuracy, sensitivity analysis and newly introduced relative ranking score, Glide provided reasonably consistent results in all respects for the system studied in the present work. Whereas GOLD and AutoDock also demonstrated better performance, AutoDock results were found to be significantly superior in terms of scoring accuracy compared to the rest.CONCLUSION:Present analysis serves as a useful guide for researchers working in the field of lead optimization and for developers in upgradation of the docking programs.

Ni 0.5 Cu 0.25 Zn 0.25 Gd x Fe 2 - x O 4 ( x = 0.0, 0.025, 0.05, 0.075, 0.1) ferrites were synthesized using an oxalic-based precursor method. A single phase Ni-Cu-Zn-Gd ferrite was observed from X-ray diffraction (XRD) data except for higher Gd content. For x = 0.1, a secondary phase due GdFe2O3 was observed. The particle size was observed to decrease and the lattice constant to increase with increasing Gd doping concentration. The IR spectra confirmed the existence of bands corresponding to spinel ferrites. The IR band positions were observed to shift towards higher positions with increasing Gd doping concentration. The saturation magnetization, coercivity and remanence magnetization were observed to increase as a result of Gd doping. The substitution of Gd ions in the place of Fe ions resulted in changes in the structural and magnetic properties due to replacement of smaller ionic radii Fe ions by larger ionic radii Gd ions.

Strontium Bismuth Borosilicate (SrBiBS as N) glasses doped with Tb3+ ions (N: Tb) and co-doped with Sm3+/Tb3+ (N: SmTb) were synthesized through the process of classical melt quenching. The structural and optical properties are investigated through energy dispersive spectroscopy; X-ray diffraction, Differential thermal analysis (DTA) and Fourier transform infrared spectra (FTIR), Optical absorption (OA) and photoluminescence (PL) spectral studies. X-ray diffraction indicates amorphous nature of glass. DTA curves explained the thermal stability and stress parameters of glasses. FTIR spectrum indicates existing vibrations of borate and silicate units. The absorption spectra have shown nine absorption bands of Tb3+ ions in the visible and NIR regions, due to transitions from ground state F-7(6). In visible region, absorption spectra of co-doped glasses exhibited two bands of Tb3+ and three bands of Sm3+ with hyper sensitive transitions at 375 nm (F-7(6)->(5)G(6)) and 401 nm(H-6(5/2)-> P-6(3/2)). Photo Luminescence (PL) spectra of N: Tb and N: SmTb glasses is recorded at 375 nm excitation. N: Tb glasses have shown green emission corresponding to D-5(4) -> F-7(5) transition. In all N: SmTb glasses, addition of Tb3+ ions has enhanced Sm3+ emission which is connected to quenching of Tb3+ emission. Moreover, 0.8 mol% of Tb3+ ions in co-doped glass (N: SmTb8) has shown maximum emission. The energy transfer process was inferred from shortening of decay times observed in N: SmTb glasses. The decay profiles fitted with Inokuti-Hirayama model suggests that the electric dipole-dipole interaction(S=6) between Sm3+ and Tb3+ might dominate in energy transfer mechanism with probability PET and energy transfer parameter Q of 113-173 S-1 and 9.9-12.0 respectively. The color chromaticity (CIE) coordinates from PL emission of N: Tb & N: SmTb glasses have covered Green, Orange red and yellow (warm-light) regions with coordinates in ranges of x = 0.39-0.62 and y = 0.34-0.56. The color temperatures in range of 1713 K-4258 K. (C) 2019 Elsevier B.V. All rights reserved.

Glasses of the composition 30BaO-2Ga(2)O(3)-(27.8-x)B2O3-4OSiO(2)-xCe(2)O(3) (0 <= x <= 1.0) were synthesized by conventional melting and quenching process. The samples were characterized by XRD, EDS, TG-DTA, FT-IR and Raman studies. Optical absorption (OA) and photoluminescence (PL) spectral studies were performed. X-ray diffraction patterns of samples have clearly confirmed the amorphous nature of the samples. Differential thermal analysis indicated thermal stability of glasses. Raman and FTIR spectra have exhibited different fundamental vibrational bands of borate and silicate structural units. The absorption spectra exhibited four absorption bands of Tb3+ ions from the ground state F-7(6) in the visible and NIR regions. In addition, a feeble band corresponding to 4f (F-2(J)) -> 5d ((2)A(1)g) absorption transition of Ce3+ ions at 416 nm is also located in these spectra. Optical bandgap (E-g) evaluated using Tauc plots, is observed to decrease with increase of Ce2O3 up to 0.6 mol%. Luminescence spectra (recorded at lambda(exc) = 329 nm) of glass co-doped with 0.6 mol% CTb exhibited the maximal PL output. The non-exponential time decay profiles are finely fitted to Inokuti-Hirayama (I-H) model for S = 6. This observation suggests that the energy transfer mechanism between Ce3+ -> Tb3+ is connected with the dipole-dipole interaction. The CIE coordinates of 0.6CTb glass are estimated to be (0.257, 0.307). These values are found to be nearer to the standard values of ideal white light and hence it is concluded that the glass of this composition is useful for white LEDs. (C) 2019 Elsevier B.V. All rights reserved.

Stupendous progress in realizing optical materials is due to extreme strides which were adapted so far in understanding optical properties of materials. Keeping this in view a series of Bismuth Borosilicate glasses modified with strontium and doped with various concentrations of Sm3+ (SrO-Bi2O3-B2O3 -SiO2-Sm2O3) have been prepared by classical melt quench technique. These glasses were structurally characterized by XRD to confirm amorphous nature. Vibration mode analysis of samples has been analyzed by infrared transmission spectroscopy. This paper show cases various optical phenomena such as absorption and luminescence which plays a key role in design of engineered optical materials. To understand absorption, optical excitation, emission and time decay process optical spectroscopy measurements were done. Judd-Ofelt (JO) theory was employed to determine intensity parameters Omega(lambda= 2,4,6) for symmetry of ligand environment existing among Sin(3+) ions. From emission spectra various radiative parameters like transition probability (A(r)), branching ratios (beta(r)) and radiative time were determined. Emission bands of (4)G(5/2) -> H-6(5/2) (560 nm), (4)G(5/2) -> H-6(7/2) (599 nm) (4)G(5/2) -> H-6(9/2) (636 nm) and (4)G(5/2) -> H-6(11/2) (708 nm) have been recorded with excitation at 401 nm. Above all emission wavelengths 599 rim is more intense and has shown a bright orange emission. Among four emission bands corresponding to (4)G(5/2) -> H-6(7/2) transition in emission spectra shows high (sigma(E)) peak stimulated emission (22.85 x 10(-22) cm(2)) and optical gain (O.G) is (28.33 x 10(-25) cm(2)s) assure optoelectronic applications. The life time tau( exp )of excited level (4)G(5/2) was determined through decay and non-exponential decay curves. Inokuti-Hirayama model was used to fit non exponential curve for the analysis of luminescence quenching, quantum efficiency (96%), transfer mechanism of energy among Sin(3+) ions to ensure Laser applications. CIE colour chromaticity coordinates of present Sm3+ doped glasses also suggest the synthesized glasses are suitable improvement of orange-red lasers.

The (NPbPEr) glasses of the composition (20-x) Na2SO4–20PbO–60P2O5-xEr2O3 (x = 0.1, 0.3, 0.5, 0.7, 1.0 mol %) are synthesized by melt quenching process. The basic characterization studies like XRD and EDS have confirmed amorphous nature and contents of the samples. The spectroscopic studies viz., optical absorption, photoluminescence (PL) and decay profiles were carried out. The PL spectra exhibited an intense sharp green emission peak at 544 nm due to 4S3/2 → 4I15/2 transition of Er3+ ions both in down-conversion (DC, λexc = 377 nm) and up-conversion (UC, λexc = 977 nm) PL spectra. The spectra also exhibited a broad intense NIR band at 1532 nm ascribed to 4I13/2→4I15/2 transition of Er3+ ions at λexc = 977 nm. The analysis of the spectra indicated 0.5 mol% of Er2O3 is the optimal concentration for achieving maximal PL output both in the green and in NIR regions. The CIE color coordinates and the corresponding CCT (K) values were estimated from both UC and DC emission spectra. Overall analysis of the results suggested that the investigated glasses are potential candidates for getting intense green light emission and are quite suitable as optical fibre amplifiers in the green and NIR (around 1.5 μm) regions.

Yttrium alumino bismuth borosilicate (YABiBS) glasses doped with RE3+ ions (Eu3+, Dy3+, Dy3+ - Eu3+) have been synthesized via standard melt quenching technique and their emission properties were investigated. Optical analysis of these glasses is characterized by absorption and luminescence. XRD spectra reveal that these glasses have amorphous nature. The absorption spectra of these co-doped glasses consist five bands of Dy3+ which are assigned to H-6(15/2) -> F-6(3/2) (750 nm), F-6(5/2) (796 nm), F-6(9/2) (1085 nm), F-6(11/2) (1264 nm), H-6(11/2) (1677 nm) and another four bands of Eu3+ assigned to F-7(0)-> L-5(6) (393 nm) Meza-Rocha et al. (2017) [5], D-5(2) (464 nm), F-7(6) (2097 nm), and F-7(1) -> F-7(6) (2202 nm). It is also witnessed a broad band having electronic transition S-1(0) -> P-1(1) is due to Bi3+ ions. Optical band gaps, nephelauxetic ratio, and bonding parameters are discussed by using optical absorption data. Eu3+ single doped glasses show five emission bands, with the n-UV excitation wavelength 393 nm, in which characteristic feature red emission (612 nm) is recognized with transition (Meza-Rocha et al., 2017 [5]) D-0 -> F-7(2). At the same time, Dy3+ single doped glasses illuminated with the excitation wavelength of 385 nm shows their known natural emissions blue (481 nm) and yellow (574 nm), having transitions F-4(9/2) -> H-6(15/2) and F-4(9/2) (->) H-6(13/2) respectively. Emission for co-doped glasses Dy3+-Eu3+ are excited with the different selected ultraviolet wavelengths such as 464 nm, 392 nm, 385 nm, 363 nm, and 348 nm. It can be observed that tunable emission from both the ions (Dy3+, Eu3+) from orange reddish emission to white emission. The energy transfer from Dy3+ to Eu3+ is manifested by the quadrupole-quadrupole mechanism, which is confirmed by Inokuti-Hirayama (I-H) modal based on lifetime decay curves. Also, the efficiencies and probabilities of energy transfer are determined based on the results of decay curves. The CIE color coordinates of DE1.0 glass with the excitation 348 nm gives x, y coordinates as (0.332, 0.342) which confers the good white emission. CCT value for this glass is around 5520 K shows that useful for cool WLED applications.

Trivalent europium ions doped yttrium alumino bismuth borosilicate glasses (YABiBS) of the composition are synthesized by the melt - quenching method. The structural, thermal and spectral properties of the prepared glasses have been investigated by XRD, EDS, FT-IR, DTA, optical absorption, photoluminescence and decay profiles. XRD indicated the amorphous nature of the samples. From the DTA traces thermal Parameters like Delta T, S and H are evaluated to verify the thermal stability of the titled glasses. ETIR spectra exhibited bands due to various fundamental vibrational units of borate and silicate groups. The optical absorption spectra exhibited the bands due to F-7(0) -> (5)G(4), F-7(0) -> L-5(6), F-7(0) -> D-5(2), F-7(0) -> F-7(6), and F-7(1) -> F-7(6) transitions of Eu3+ ions. In addition the absorption spectra also exhibited a band due to S-1(0) -> P-1(1) transition of Bi3+ ions. From the absorption spectra, the optical band gap and Urbach energies and also nephelauxetic ratios were evaluated. The emission spectra (excited at 392 nm) exhibited five lumines- cence bands at 577, 590, 612, 651 and 700 nm assigned to D-5(0) -> F-7(0), D-5(0) -> F-7(1), D-5(0) -> F-7(2), D-5(0) -> F-7(3), and D-5(0) -> F-7(4) transitions of Eu3+ ions, respectively. The absorption and emission spectra were char- acterized using Judd-Ofelt (J-O) theory and radiative parameters viz., radiative transition probability (A(R)), branching ratio (beta(R)), and luminescence quantum efficiency (eta), radiative life time (tau), stimulated emission cross-section (sigma(E)(P)) were evaluated. The values of radiative parameters are found to be the highest for the transition D-5(0) -> F-7(2) of 0.6mol% Eu3+ doped YABiBS glass (BE0.6). The co-doping of Bi3+ ions (10.0mol%) caused a substantial enhancement (nearly three times) in the intensity of this red emission. These results suggested the energy transfer between Bi3+ ions and Eu3+ ions. The energy transfer efficiency has been explained in terms of structural modifications taking place in the glass network. (C) 2018 Elsevier B.V. All rights reserved.