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Oxyfluoride (P2O5 + Bi2O3 + Na2CO3 + SrCO3 + ZnF2) glasses doped with different dysprosium (Dy3+) ion concentrations (0.5, 1.0, 1.5 & 2 mol %) have been synthesized using conventional melt quenching technique. The Physical and optical parameters such as density (ρ), refractive index (n), polaron radius (rp), interionic distance (ri), field strength (F), electron polarizability (αe), molar refractivity (RM), reflection loss (R), etc., were evaluated. The X-ray diffractograms were recorded in the 10–900 region, showed amorphous nature. Surface morphological studies were performed with SEM and elemental analysis has also been performed with EDS. The absorption spectra consist of a few well-defined high intense bands in the UV–Vis-NIR region. The optical band gaps were estimated from the tauc’s plots drawn from the absorption spectra and obtained values exhibited nonlinear behaviour with dopant ion concentration. The emission spectra were recorded by monitoring the excitation wavelength at 453 nm which consists of three emission bands at 487, 557 and 667 nm, due to f-f characteristic transitions of Dy3+ ion. The Judd-Ofelt and radiative parameters have been calculated from absorption and luminescence spectra. It has been noticed that the concentration quenching effect was observed for higher concentrations (1.5 and 2.0 mol %) in the present glass series. The emission intensity ratio between yellow and blue color bands and CIE color coordinates were evaluated. The correlated color temperature (CCT) and color purity (CP) has been evaluated using CIE 1931 chromaticity diagram. The ZnBiNaPSr: Dy1.0 glass exhibits superior luminescent properties than other concentrations and it was found to be the most prominent device for white light applications.

Co-rich ZnCo2O4 (ZCO) two-dimensional (2D) nanosheets are decorated with highly porous, glucose-derived, zero-dimensional (0D) interconnected network-like carbon nanospheres (CNS) using an in situ hydrothermal method. The content of CNS in the reaction is varied to produce two different composites (CNS@ZCO-I and CNS@ZCO-II). Their physicochemical properties are examined and compared with those of the pristine-CNS and ZCO samples. The non-stoichiometry of the elements in ZCO of the composites is quantified by X-ray diffraction using a Reitveld refinement and X-ray photoelectron spectroscopy. CNS@ZCO-II is found to be Co-rich in ZnCo2O4 compared to the other samples. The high surface area of the CNS and non-stoichiometry of Zn/Co in the composites provide a short ion/electron transport path distance, high electronic conductivity, additional electrochemical active sites, and stable structural integrity. This viable strategy offers a good interaction between the CNS and ZCO, which translates to better electrochemical activity as an electrode material for energy storage devices. The CNS@ZCO-II composite with a higher CNS concentration shows an excellent electrochemical performance of approximately 1116.24 F g−1 at 0.35 A g−1 (compared to the pristine-ZCO and CNS@ZCO-I composite).

Sm3+ ions doped strontium lithium lead borate glasses (SLLB:Sm) were prepared using a conventional melt-quenching technique. The glasses were analyzed using X-ray diffractometry and Fourier transform infrared spectroscopy, optical absorption, fluorescence spectral analysis, and fluorescence lifetime decay. The Judd-Ofelt (J-O) parameters and radiative parameters of the SLLB:Sm10 glass (1.0 mol% Sm3+ ion-doped glass) were calculated using J-O theory. From the emission spectra, among all the synthesized glass, SLLB:Sm10 glass had the highest emission intensity for 4 G5/2 →6 H11/2 transition (610 nm). Emission parameters, such as stimulated emission cross-section and optical gain bandwidth, were calculated. For all concentrations of Sm3+ ions, the decay profile showed an exponential nature and decreased when the Sm3+ ion concentration was increased due to a concentration quenching effect. This result suggests that the synthesized SLLB:Sm10 glass could be used for application in high-density optical memory devices.

Bismuth based fluorophosphate (PBNS) glasses doped with samarium ions were fabricated by well-known melt quenching method. The structural, optical and fluorescence properties of PBNS glasses, were extensively investigated via XRD, FTIR, EDAX, optical absorption and fluorescence emission along with lifetime decay analysis. The intensity parameters (Ω2, Ω4, Ω6) were calculated using the Judd – Ofelt hypothesis, which follows the Ω4 > Ω6 >Ω2 trend. PBNSSm glasses doped with 1.0 mol% samarium ions (PBNSSm10) had a greater emission peak intensity than the produced glasses according to the emission spectra. The 4G5/2 → 6H7/2 transition emitting the radiation at 597 nm was more intense than the other transitions and got higher values for optical gain bandwidth (10.70 x 10−25 cm3), stimulated emission cross-section (10.05 x 10−20 cm2) branching ratio (0.48), and optical gain parameter (28.65 x 10−25 cm2s). The emission spectral results have been used to evaluate the colorimetric analysis of the 1931 CIE coordinates, and CCT values fall in the visible spectrum region. Moreover, the degree of protection of the synthesized PBNS glasses against gamma radiation was also evaluated. The obtained results suggested that the PBNS glass doped with 1.0 Sm3+ ions could be useful for multi-band visible laser applications. It was also concluded that 2.0% Sm3+ addition effectively increases the gamma-ray shielding properties of PBNS glasses, and therefore PBNSSm20 can be an alternative shielding material. WOS:000861371700005 Q2

Nd3+ single and Nd3+/Eu3+ co-doped ZnF2-LiF-Na2CO3-Bi2O3-H3BO3, zinc lithium fluoroborate (ZLFNBiB) glasses with good optical properties have been prepared by high temperature melt-quenching method. The single and co-doped samples exhibiting emission bands centered at 874, 1058 and 1330 nm under the excitation of 808 nm laser diode (LD). The photoluminescence spectra for co-doped glasses were recorded under the 394 and 464 nm of xenon lamp as excitation sources. The Judd-Ofelt intensity parameters were calculated from optical absorption spectrum and radiative parameters from the emission spectrum of 0.5 mol% of Nd3+ doped glass. The large stimulated emission cross-section and branching ratio values are evaluated and compared with the other Nd3+ doped systems, the energy transfer from Eu3+ to Nd3+ ions is observed and thoroughly discussed from NIR emission spectra (λexc = 394 nm) of co-doped glasses. The decay profiles are recorded for all the concentrations of co-doped samples and the experimental lifetimes (τexp) were obtained from the decay profiles. The binding energy and Urbach energy values of prepared glass samples were calculated and discussed.

A single-phase and optimized pure white light emitting Dy3+-doped and Dy3+/Mn2+ codoped Na3Y(PO4)2 phosphors (NYPO) were synthesized by traditional solid state reaction process. The as-synthesized phosphors were characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectra and photoluminescence studies. The results suggested that the NYPO: Dy, Mn phosphors were crystallized in orthorhombic structures. The presence of dopants Dy and Mn was quantified by XPS analysis. All of the phosphors were effectively excited using a light of wavelength 351 nm and emissions in two regions, blue (~482 nm, 4F9/2→6H15/2) and yellow (~573 nm, 4F9/2→6H13/2), were obtained due to the f-f transitions of Dy3+ ions. The maximum intensities of Dy and Mn obtained were 0.07 and 0.05 for NYPO:Dy and NYPO:0.07Dy, Mn, respectively. The chromaticity coordinates, color temperatures, and color rendering indices of NYPO: 0.07Dy ((0.32, 0.33), 6194 K, and 48) and NYPO:0.07Dy, 0.05Mn phosphors ((0.33, 0.33), 5688 K, and 62) were determined. The energy transfer mechanism and oxygen vacancies that arise due to the introduction of Mn2+ ions in the NYPO:Dy phosphors, are responsible for the tuning of cool white light to pure day white light. The introduction of Mn in the Dy doped NYPO phosphor enhances the emission intensity in the phosphor.

The calcium-based lead borate glasses doped with 1 mol% Sm3+ ions were prepared using melt quenching technique. The prepared glass samples were analyzed through an X-ray diffractometer, FT-IR, Optical absorption, Emission, and fluorescence decay analysis. Physical properties have been calculated for the prepared glasses. The absorption spectrum has been recorded for 1.0 mol% Sm3+ ions doped calcium-based lead borate glasses. From the absorption spectrum, oscillatory strengths and JO intensity parameters have been calculated. The visible and near-infrared emission spectra were recorded with 402 nm excitation for 1.0 mol% Sm3+ ions. The prepared glass shows that the highest emission intensity for 4G5/2 → 6H11/2 transition centered at 610 nm. Emission properties for the prepared glass were calculated. Decay profile has been analyzed and lifetime value for 4G5/2 exited level of Sm3+ ion calculated for 1.0 mol% Sm3+ ions doped Ca-based lead borate glass: decay profile was well fitted for exponential decay 2, and the lifetime of 4G5/2 excited level is 1.041 ms. The obtained results suggested that the present 1.0 mol% Sm3+ ions doped calcium-based lead borate glass could be useful for the visible lasers and or photonic display devices applications.

Effectively electrode materials with optimized morphologies have exposed promising potential in continuous development of supercapacitor electrochemical performance over the past few years. Here, we prepared a novel design of CoMoO4 (CMO) microstructures through hydrothermal/solvothermal method and obtained two different morphologies: rod-like and pebbles-like, respectively. The phase purity, structural characteristics and chemical bonding of the samples were analysed by x-ray diffraction (XRD), Fourier Transform – Infrared (FT-IR) analyses. The morphological characteristics and composition of the samples were examined using Field emission-scanning electron microscopy (FE-SEM) and Energy dispersive x-ray spectroscopy (EDS) analyses respectively. The elemental composition and chemical states of the materials was further evaluated using XPS analysis. Electrochemical behaviour of the two different CMO microstructures was evaluated using Cyclic voltammetry (CV), Galvanostatic charge discharge (GCD), and Electrochemical impedance spectroscopy (EIS) analyses. A high areal capacitance of 1.57F cm−2 for R-CMO and 2.27F cm−2 for P-CMO at 1.5 A cm−2 and superior cycling stability of 90.49% for R- CMO, 85.95% for P-CMO was retained after 2,000 cycles. The unique hierarchical architectures with good structural and electrochemical properties of the materials creates new directions in the emerging field of energy storage applications.

The oxyfluorosilicate glasses with the composition of (44-x)SiO 2 + 5Al 2 O 3 + 17 Na 2 CO 3 + 18SrF 2 + 15CaF 2 + 0.5Nd 2 O 3 + xYb 2 O 3 (x = 0.1, 0.5, 1.0 and 2.0 mol %) have been prepared by conventional melt quenching technique. The optical absorption, emission and up-conversion spectra were carried out. The strong absorption peak observed at 804 nm corresponding to the transition 4 I 9/2 → 4 F 5/2 + 2 H 9/2 . The emission spectra were recorded for Nd 3+ singly and Nd 3+ /Yb 3+ co-doped glasses with 808 nm laser diode as an excitation source. For the present investigation, the glass co-doped with 0.5 Nd 3+ , 0.5 mol% Yb 3+ ions have the highest emission intensity. PL up-conversion (UC) emission have been analysed under the excitation of 980 nm laser diode. It is observed that four intense up-conversion emission bands at around 500 nm, 537 nm, 596 nm and 662 nm ascribed to the electronic transitions 4 G 9/2 → 4 I 9/2 , 4 G 7/2 + 2 K 13/2 → 4 I 9/2 , 4 G 5/2 + 2 G 7/2 → 4 I 9/2 and 4 G 7/2 + 2 K 13/2 → 4 I 13/2 respectively. The green emission band at 500 nm ( 4 G 9/2 → 4 I 9/2 ) has the highest peak intensity for 0.5 mol % Nd 3+ and 2.0 mol % Yb 3+ ions co-doped glass. For the present work the values for n = 1.76, 1.93 and 2.25 for UC emission at 500, 596, 662 nm respectively. The value n≈2 suggesting that two photons are involved in the UC process of present glass system. The above results suggesting that the prepared glasses co-doped with Nd 3+ /Yb 3+ ions may be used for green light emitting display device applications.

Fluoroborosilicate glasses of composition 35SiO2-25B2O3-10Na2CO3-15NaF-15CaF2-xNd2O3 (where x = 0.1, 0.5. 1.0, 2.0 mol%) were prepared by melt quenching technique and various physical properties have been calculated. From the absorption spectra J-O Intensity parameters Ωλ (λ = 2, 4, 6) and radiative properties are evaluated by using J-O theory. The high values of Ω2 = 4.213 × 10−20 cm2, Ω4 = 5.345 × 10−20 cm2, Ω6 = 5.526 × 10−20 cm2 suggest that among the prepared glasses 0.5 mol% Nd glass is more asymmetric, more covalent and rigid in nature. The emission spectra were recorded with 808 nm laser as excitation source. The strong NIR emissions were observed at 876 nm, 1056 nm, 1328 nm corresponding to the transitions 4F3/2 → 4I9/2, 4F3/2 → 4I11/2, 4F3/2 → 4I13/2 respectively. Stimulated emission cross -section (σemi) and Gain bandwidth (σemi × Δλeff) were calculated. For 0.5 mol% Nd these values are found to be 3.30 × 10−20 cm2, 11 × 10−26 cm2. From the decay curve analysis the lifetime values for 4F3/2 level have been determined and these values are decreased with increase in Nd3+ ions concentration. These results may suggest that the prepared SBNCNd05 (Nd = 0.5 mol%) glass could be useful for 1056 nm laser applications.

In this study, a new green emitting CaZn2(PO4)2:Tb3+ phosphors were synthesized through solid-state reaction route. The phosphors were characterized structurally by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). All the synthesized phosphors were crystallized in triclinic crystal structure with P 1 ¯ space group. The phosphate groups in the phosphors were confirmed by FTIR analysis. The surface elements O 1s, P 2p, Ca 2p, Zn 2p and Tb 3d were studied by high-resolution XPS spectra. Upon excitation at 378 nm, the dominant green emission of CaZn2(PO4)2:Tb3+ phosphors at 542 nm were noticed in the emission spectra. For various emission wavelengths (at 435 and 489 nm) and constant excitation wavelength (at 378 nm), the decay curves have shown two different decay dynamics of phosphors. The lighting properties such as Commission International de l’Eclairage (x = 0.319, y = 0.398) and color temperature (5995 K) were calculated.

A high-temperature solid state reaction route was employed to synthesize the phosphate based new orange-red emitting trivalent samarium (Sm3+) ions doped calcium zinc phosphate (CZP: CaZn2(PO4)2) phosphor. The crystalline phase formation was studied by X-ray diffraction analysis. The surface properties of the phosphor were investigated by X-ray photoelectron spectroscopy. Under the excitation of 402 nm, the emission spectra of CZP:Sm3+ has several peaks and the dominant peak at 596 nm was ascribed to 4G5/2 → 6H7/2 transition. The concentration quenching effect of Sm3+ in CZP phosphor was observed for 5 at%. The mechanism of energy transfer between similar Sm3+ ions was determined to be quadrupole-quadrupole interaction. The decay curves of all phosphors were well fitted to the first-order exponential function. The chromaticity coordinates were located in the orange-red region of the chromaticity diagram. Therefore, these results suggest that the orange-red emitting new CZP:Sm3+ phosphor to be used in the phosphor-converted white light emitting diodes.

Er 3+ doped SiO 2 -Al 2 O 3 -Na 2 CO 3 -SrF 2 -CaF 2 oxyfluoride glasses have been prepared by melt quenching method and were investigated by optical absorption spectra. Judd-Ofelt intensity parameters were calculated and used to predict radiative properties of 1.0 mol% of Er 3+ ions doped glass. The visible photoluminescence and lifetime spectra were recorded under the 379 nm excitation source. In the near infrared region the emission spectra and their decays corresponding to 4 I 13/2 → 4 I 15/2 laser transition of Er 3+ ions, were recorded by excitation source of laser diode at wavelength of 980 nm. The lifetime of 4 I 13/2 level has been decreased (6.38–1.95 ms) with increasing of Er 3+ ion concentration from 0.1 to 2.0 mol%. The upconversion studies were investigated as a function of Er 3+ ions concentration in oxyfluoride glasses. The mechanism involved in the energy transfer process corresponding to an increase in the green and red emission upconversion intensities with increasing of Er 3+ ions concentration were discussed. The spectroscopic characteristics of 1 mol% of Er 3+ doped oxyfluorosilicate glasses were compared with other host materials. The stimulated emission cross-section and gain bandwidth have been calculated and found to be 9.8 × 10 −21 cm 2 and 0.52 × 10 –25 cm 3 for the 4 I 13/2 → 4 I 15/2 (1.535 µm) transition and is most useful for optical amplifier applications.

The fluoride-based bismuth phosphate (PBNS) glasses are doped with Dysprosium ions are fabricated by using the method conventional melt quenching. For synthesized PBNS glasses physical parameters were evaluating, moreover, the structural, optical, and fluorescence properties were analyzed/studied by XRD, FTIR, EDAX, photoluminescence study analysis, and optical absorption. The optical band gap is estimated based on the tauc's curve extracted from the absorption spectrum, and the value obtained shows a non-linear behavior with the concentration of doping ions. The intensity parameters (Ω2, Ω4, Ω6.) were evaluated using Judd – Ofelt theory and which follows Ω2 > Ω4 > Ω6 trend. From the emission spectra, the PBNSDy glasses doped with 1.0 mol% Dysprosium ions (PBNSDy10) attains the higher emission peak intensity among the prepared glasses. The 6H15/2 → 6F11/2 transition emitting the radiation at 473 nm was more intense than the other transition and attains a higher value for optical gain bandwidth (28.66 × 10−25 cm2S), Stimulated emission cross-section (5.45 × 10−21 cm2) and branching ratio (0.63). The emission spectra are used to evaluate by colorimetric analysis of the 1931 CIE color coordinates, Y/B intensity ratio, and CCT values to see the adaptability of the fluorophosphate glass to solid-state white light LED applications.

Effect of Nd 2 O 3 concentrations on optical properties and upconversion studies were investigated for oxyfluorosilicate glasses with composition of SiO 2 -Al 2 O 3 -Na 2 CO 3 -SrF 2 -CaF 2 . The Judd-Ofelt (JO) intensity parameters, Ω λ (λ = 2, 4 and 6) as well as radiative properties for the 4 F 3/2 level of Nd 3+ ion have been evaluated from the absorption spectra of 1.0 mol% Nd 2 O 3 -doped glass. For all the glass samples, the strong NIR emissions were observed at 891, 1058 and 1330 nm and have been attributed to 4 F 3/2 → 4 I 9/2 , 11/2, 13/2 transitions respectively. The stimulated emission cross-section for the 4 F 3/2 → 4 I 11/2 transition is evaluated and found to be 4.24 × 10 –20 cm 2 . From the decay curves, experimental lifetimes (τ exp ) of the 4 F 3/2 level have been determined and are found to be 363, 340, 205, 134, 122 and 54 μs for 0.1, 0.5, 1.0, 1.5, 2.0 and 3.0 mol% Nd 3+ ions doped glasses, respectively. By exciting the prepared glass samples at 808 nm, the upconversion of infrared light into blue, green, yellow and red emission have also observed. These results indicate that the present glasses could be useful for opto-electric devices and solid state laser applications.

The various concentrations of trivalent samarium ions activated SiO 2 +B2O3 + Na2CO3 + NaF + CaF2 (SBNC) glasses have been prepared with the conventional melt quenching method. Various physical parameters like density, refractive index , thickness, etc were evaluated/calculated for prepared glasses. The synthesized glasses were subject to analysis through FTIR, absorption, photoluminescence excitation, emission and fluorescence decay measurements. Judd-Oflet parameters (Ω 2, Ω4 and Ω6) were estimated for all investigated SBNCSm glasses and calculated various radiative parameters. The fluorescence emission spectra consist of four sharp peaks centered at 564 nm (4G5/2 →6H5/2), 600 nm (4G5/2 → 6H7/2), 660 nm (4G5/2 →6H9/2), and 710 nm (4G5/2 →6H11/2). The glass doped with 0.5 mol % Sm3+ ions (SBNCSm05) has the highest emission intensity for 4G5/2 →6H7/2 transition (600 nm (orange)). The characteristic fluorescence emission parameters were calculated. The SBNCSm05 glass attains the higher values of stimulated emission cross-section ( σ emi = 11.23 × 10−20 cm2), the gain bandwidth ( σ emi x Δλeff = 16.22 × 10−25 cm3) and optical gain parameter ( σ emi x τR = 19.85 × 10−25 cm2s). The lifetime of excited of Sm3+ ions (4G5/2) was estimated using the least square fitting method. The CIE chromaticity coordinate values of investigated glasses confirmed the emitted radiation fall in the visible reddish-orange region of the EM spectrum. Moreover, the shielding capacity of SBNCSm glasses against gamma photons and fast neutrons were extensively evaluated using Py-MLBUF online software. The results clearly shows that the different concentrations of Sm3+ ions into SBNC glasses improved both shielding and optical properties. The obtained values suggested that the SBNCSm05 and SBNCSm20 glasses can be used as a potential candidate in photonic device applications and radiation shielding applications.

Over the past few decades, increasing attention has been focused on overcoming the scarcity of fresh water resources, with the rapid effluents of dyes from modern chemical industries causing issues in photosynthetic activity of aquatic organisms. In the process of recycling wastewater, the degradation of dye pollutants such as 4-nitrophenol, methylene blue, and methyl orange has become more crucial. Noble metal (silver, gold, palladium, and platinum) materials have significant potential applications in the areas of water purification, conversion of automobile exhaust emissions, and catalysis. Ultra-small alkylamine-capped palladium nanoparticles (APd NPs) with sizes below 10 nm are synthesized using hexadecylamine (HDA) as a stabilizing material, and HDA can prevent the irreversible aggregation of small-sized nanoparticles in solution-based reactions. The fabricated ultra-small APd NPs are investigated using UV–Vis, XRD, SEM, TEM, FTIR and TGA studies. In the presence of NaBH4 as a reducing agent, the APd NPs achieve high catalytic performance toward the degradation of dye pollutants such as 4-nitrophenol, methylene blue and methyl orange. Catalytic activity of alkylamine capped palladium nanoparticles for organic pollutant degradation.

A single-phase white-light-emitting phosphor, K3ZnB5O10:Dy3+, has been synthesized by a conventional solid-state reaction method. X-ray diffraction (XRD) analysis was used to determine the monoclinic crystal structure of phosphors. The surface states, B 1s, O 1s, K 2p, Zn 2p, and Dy 3d of the phosphor was quantified by X-ray photoelectron spectroscopy (XPS). Diffuse reflectance spectroscopy (DRS) revealed double absorption edges at 3.27 and 5.46 eV for K3ZnB5O10 matrix. The formation of defect-levels, zinc interstitials ( Z n i ) , zinc vacancies ( V Z n ) , oxygen antisites ( O Z n ) and oxygen vacancies ( V O ) in K3ZnB5O10:Dy3+ phosphors were identified by photoluminescent (PL) spectroscopy. The emissions at 405 nm (violet-I), 434 nm (violet-II), and 467 nm (blue) are due to intra-band transitions of ( F X → V Z n ) , ( Z n i → V Z n ) and ( Z n i → O Z n ) of the host, respectively. Similarly, the emission at 517 nm (green) corresponds to the transition from free excitons to the oxygen vacancies in the host ( F X → V O ) . The emissions at 575 and 665 nm are assigned to the f-f transitions of Dy3+ ions within the host matrix. An energy level diagram is proposed to describe the host emission and possible energy transfer from the host to dopant ions in the single-phase phosphor. The phosphor shows good thermal stability with activation energy of 0.52 eV. The combined emissions in the blue, green, yellow, and red regions resulted in white light emission with CIE coordinates of (0.256, 0.258) on the CIE diagram.

A trivalent rare-earth ion (Sm3+ )-doped LiNa3 P2 O7 (LNPO) phosphor was synthesized using a conventional high-temperature solid-state reaction route. A predominant orthorhombic phase of LNPO was observed in all X-ray diffraction patterns. The surface states of the LNPO:Sm phosphor were confirmed by X-ray photoelectron spectroscopy. Under 401 nm excitation, the Sm-doped LNPO phosphors showed sharp emission peaks at 563, 600 and 647 nm that are related to the f-f transition of Sm3+ ions. The optimum concentration of Sm3+ (9 mol%) produced Commission Internationale de l'Eclairage chromaticity coordinates, color rendering index and correlated color temperature of (0.564, 0.434), 42 and 1843 K, respectively.

The spectroscopic properties of Tellurium Calcium Zinc Niobium oxide Borate (TCZNB) glasses of composition (in mol%) 10TeO2 + 15CaO + 5ZnO + 10 Nb2 O5 + (60 - x)B2 O3 + Nd2 O3 (x = 0.1, 0.5, 1.0 or 1.5 mol%) have been investigated experimentally. The three phenomenological intensity parameters Ω2 , Ω4, Ω6 have been calculated using the Judd-Ofelt theory and in turn radiative properties such as radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes have been estimated. The trend found in the JO intensity parameter is Ω2 > Ω6 > Ω4 If Ω6 > Ω4 , the glass system is favourable for the laser emission 4 F3/2 → 4 I11/2 in the infrared (IR) wavelength. The experimental values of branching ratio of 4 F3/2 → 4 I11/2 transition indicate favourable lasing action with low threshold power. The evaluated total radiative transition probabilities (AT ), stimulated emission cross-section (σe ) and gain bandwidth parameters (σe × Δλp ) were compared with earlier reports. An energy level analysis has been carried out considering the experimental energy positions of the absorption and emission bands.

In this study, various concentrations of Pr3+ doped LiPbB5O9 phosphors were synthesized via solid state reaction technique. For the prepared phosphors, X- ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric study (TG-DSC), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) characterizations were performed. Crystallinity nature of LiPbB5O9:Pr3+ phosphor was studied by XRD analysis. Morphology of the prepared phosphors was investigated by SEM studies. Various functional groups present in LiPbB5O9:Pr3+ phosphor were identified through FTIR analysis. Variation in weight of the prepared phosphor with the temperature (endo- and exothermic temperatures) was studied by TG-DSC studies. Optical energy band gaps for different concentrations of Pr3+were obtained from DRS studies. Photoluminescence (excitation and emission) spectra were investigated at λemi = 609 nm and λexc = 443 nm, respectively. From energy transfer studies, it was identified that the energy transfer between Pr3+ ions in LiPbB5O9 phosphor was ascribed to dipole-dipole interaction. Lifetime decay curves of 1D2 level were studied at λemi = 609 nm and λexc = 443 nm wavelengths. CIE colour coordinates of LiPbB5O9:Pr3+ phosphors were calculated from the emission data. From all these studies, it can be mentioned that LiPbB5O9:0.05Pr3+ phosphor may be utilized for the blue light converting red phosphor in white LED applications.

Self-assembled hierarchical rhombus-, spindle-, and peanut-like zinc cobaltite (ZnCo2O4, ZCO) microstructures have strategically engineered using an effective solvothermal approach. The various morphology-regulated ZCO samples have obtained by altering the concentration of precursors in the solvent. Effective strategic methods led to various regulated morphologies, as well as different physicochemical properties, such as the surface area/pore size/volume, crystalline nature, and non-stoichiometry of Zn and Co in the ZCO samples. The metal (Zn/Co)/O deficiencies have quantitatively estimated via X-ray photoelectron spectroscopy and confirmed by the Rietveld refinement of ZCO samples using X-ray diffraction data. A mechanistic study has performed to investigate the formation mechanism of the precursor concentration-dependent self-assembled ZCO microstructures. We demonstrate that the specific capacitance of ZCO has proportional to the Zn-deficiency/Co-excess. The Co-deficient-dependent electrochemical properties have studied for three samples and a decline in the following order: P-ZCO (1608.95 F g−1 at 0.35 A g−1) > S-ZCO (1007.48 F g−1 at 0.35 A g−1) > R-ZCO (629.05 F g−1 at 0.35 A g−1). The simple and inexpensive method of synthesized non-stoichiometric ternary metal oxides micro/nanostructures will introduce new directions in this emerging energy field.

In this investigation, the synthesis of glass ceramics of Sr1-xBaxBi2B2O7 (for 0 ≤ x ≤ 1.0) and its structural, morphological and vibrational properties are presented. Sr1-xBaxBi2B2O7 glass ceramics are fabricated through standard melt-quenching method followed by annealing at temperatures below its glass transition temperature. The fabricated glass ceramic compounds are studied through X-ray diffraction technique for the structural characterization where the glass like nature with an indication of crystalline peak is observed. There is a shift in the observed peak with the increase in the barium concentration indicating the changing local crystal lattice parameters. The samples were studied through Scanning Electron Microscopic imaging to visualize its morphology, where it is evident that large grain are grown indicating mixed glassy and crystalline nature. The structure of synthesized glass ceramics was determined using quantum chemical calculations carried out by density functional theory (DFT) employing B3LYP functional in conjunction with SDD basis set. FTIR and Raman spectra were recorded and vibrational analysis of these materials was made using potential energy distribution (PED) obtained in DFT computations. NLO behaviour and HOMO-LUMO energies of these glass ceramics were also evaluated.

Near white-light emitting LiNa 3 P 2 O 7 :Dy 3+ phosphors were prepared by a conventional solid-state reaction method. The orthorhombic crystal structure of the phosphors was confirmed using X-ray diffraction (XRD), and the valence states of the surface elements were determined from the binding energies of Li 1s, O 1s, Na 1s, P 2p, and Dy 3d by X-ray photoelectron spectroscopy (XPS). Attenuated total reflectance (ATR) - Fourier transform infrared (FT-IR) spectroscopy was employed to identify the pyrophosphate groups in the phosphors. Diffuse reflectance spectra (DRS) show the absorption bands of the Dy 3+ ions in the host material. Intense blue (481 nm) and yellow (575 nm) emissions were obtained at an excitation wavelength of 351 nm and are attributed to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions of Dy 3+ ions, respectively. The combination of these two intense bands generates light emission in the near-white region of the chromaticity diagram.

In this paper, for the first time, the visible fluorescence properties, resonance energy transfer mechanism responsible for non-radiative decay rates of 5D4 → 7F5 transition and also quenching of fluorescence intensity of the 5D3 → 7F5 transition of various concentrations of Tb3+ ions in LBZLFB glasses are reported. Optical absorption, fluorescence spectra and quantum efficiencies are measured and analysed. Green fluorescence related to 5D4 → 7F5 (548 nm) transition is registered under excitation of 378 nm of Tb3+ ions. Based on excitation and fluorescence measurements, several spectroscopic parameters for Tb3+ ions are examined as a function of concentration by Judd–Ofelt theory to judge the suitability of studied glasses for display devices and fibre lasers.

In this paper we have reported the effect of co-doped on the luminescence properties of Y 2 O 3 :Eu 3+ phosphors. The Y 2 O 3 :Eu 3+ phosphors prepared by different methods such as combustion synthesis, precipitation methods, Pechini sol–gel method. XRD, SEM and FTIR analysis were carried out for the confirmation of phase purity, surface morphology and M O vibration in host lattice. Here we focused on the more desired route of synthesis of Y 2 O 3 :Eu 3+ phosphor for high lumen output with low cost synthesis route. Detailed study has been presented on the emission properties of Y 2 O 3 :Eu 3+ (Eu = 1 m%) due to various concentration of Li + and Zn 2+ by urea combustion method, precipitation method and Pechini sol–gel method. In this investigation, we found that PL intensity strictly depends on the method of preparation and concentration of co-dopant Li/Zn, in sample Y 2 O 3 :Eu 3+ (Eu = 1 m%), and intensity of red emission peak enhances by, accountable factor by adding Li + and Zn 2+ in Y 2 O 3 :Eu 3+ . Thus the prepared phosphor is a promising red phosphor used in lamp industries.

Trivalent rare earth ions show interesting optical properties and such properties have high technological applications of rare earth doped materials such as energy saving lighting devices, optical displays, optical fibers, amplifiers and lasers. Among these materials rare earth ions doped glasses are of great important to optoelectronics and are widely used in fiber amplifiers and solid state high power lasers for telecommunications and light emitting diodes. Near-infrared luminescence for high power lasers is a current requirement in modern fiber optic telecommunication network and emphasis has to put in recent advances of NIR emitting materials for amplifiers, fiber lasers and waveguides. We make an effort to satisfy the above needs by preparing the LCZSFB glasses doped with Sm3+, Dy3+, Eu3+, Tb3+ and Nd3+ rare earth ions. In this review, optical properties of LCZSFB glasses doped with Sm3+, Dy3+, Eu3+, Tb3+ and Nd3+ rare earth ions and the current status of their applications is given.

The alkaline phosphate based LiNa3P2O7:Tb3+ phosphors are prepared by solid state reaction method. X-ray diffraction (XRD) analysis shows that all the powders possess orthorhombic structure. Fourier transform infrared (FTIR) spectroscopy studies suggest that the phosphor belong to the diphosphate family. The morphology of the phosphors is identified by scanning electron microscopy (SEM). Upon 378 nm excitation, the LiNa3P2O7:Tb3+ phosphors shown emission bands at 482, 545, 588 and 620 nm corresponding to the transitions 5D4→7F6, 5D4→7F5, 5D4→7F4 and 5D4→7F3, respectively. The optimized concentration of Tb3+ in LiNa3P2O7 phosphor is found to be 9 mol%. The concentration quenching mechanism was proved to be the exchange interaction between two nearest Tb3+ ions with the critical distance (Rc) of 1.18 nm. The Commission International de l'Eclairage (CIE) coordinates evidence that the phosphors emit in the green light region. Thermoluminescence properties of the prepared phosphors are studied by pre-irradiating the powders with different doses of UV irradiation. The kinetic parameters of TL glow curves are calculated using Chen's peak shape method.

The oxyfluoroborosilicate (SiO2-B2O3- Na2Co3-NaF-CaF2) glasses activated with varied concentrations of trivalent Erbium ions have been prepared by using conventional melt quenching method. The structural, optical and luminescence properties were examined with X-ray diffraction, X-ray Photoelectron, Fourier Transform Infrared, Optical absorption, fluorescence emission spectra and lifetime decay analysis. From the absorption spectra of the prepared glasses, oscillatory strength of each band was calculated and evaluated the bonding parameters (β, δ) values. Judd-Ofelt theory had been used to determine the spectral intensity parameters (Ωλ = 2,4 and 6) and some important radiative parameters like total radiative transition probability (AT), radiative lifetime (τR) and radiative branching ratios were also calculated for 4I15/2 → 4I13/2 transition. Optical band gap energy (Eopt) estimated/determined for direct and indirect allowed transitions. From the NIR emission spectra, 0.5 mol% Erbium ions activated glass possesses maximum intensity for 4I13/2 → 4I15/2 transition and evaluated the stimulated emission cross-section (σemi) (9.47 × 10−21 cm2), Gain bandwidth parameter (σemi x ∆λeff) (0.823 × 10−25 cm3) and gain per unit length (σemi x τmes) (51.65 × 10−25 cm2s) for this prepared glass and compared with other reported glasses. Using Mc Cumber theory, σemi was calculated for 4I13/2 → 4I15/2 transition from the absorption spectrum of 0.5 mol% Er3+ ions doped glass. The lifetime (τm) of 4I13/2 level was decreased from 6.94, 6.61, 5346, 5.44 and 2.74 ms with the increase in Erbium ions concentrations from 0.05, 0.1, 0.5, 1.0 and 2.0 mol% respectively. This decrease may be due to concentration quenching effect. The high values of (σemi) (9.47 x 10−21 cm2), (σemi x ∆λeff) (0.823 × 10−25 cm3) and τm (5.45 ms) for 0.5 mol% of Er3+ ions activated oxyfluoroborosilicate glass suggesting that the glasses could be used as potential candidate for 1.53 μm optical amplifier applications.

A novel bioactive glass of the composition B2O3–SiO2–Na2O–ZrO2: MO is synthesized through conventional melt quenching technique. Role of some modifier oxides (Li2O, MgO, ZnO, and CaO) on bioactive behaviour through optical and spectroscopic properties of these samples is investigated after immersing in simulated body fluid (SBF) for about a month. XRD pattern and SEM pictures of the post-immersed sample in SBF solution suggested the deposition of HAp layer on surface of the samples. pH of the test solution is enhanced in the course of immersion and showed a linear increase at the initial stage and attained saturation after a period of about 10 days. The comparison of pH of the remnant solution of the glasses mixed with different modifier oxides indicated the maximal value for Li2O mixed glasses. The IR spectra of post immersed samples exhibited vibrational bands related to carbonated hydroxy-apatite groups. The optical band gap estimated from the optical absorption spectra indicated considerable increase due to immersion in SBF and it is attributed to the deposition of HAp layer on the glass surface. Overall analysis of the results indicated Li2O mixed glasses are more efficient bioactive glasses when compared with the glasses mixed with other modifier oxides.

The varied trivalent Samarium ions activated lead borate glass with composition 40B2O3+35PbO+15Ba2CO3+(10-x)Li2CO3+ xSm2O3 (where x = 0.0, 0.1, 0.5, 1.0, 1.1, 1.5, 2.0 mol %) have been prepared by adopting melt-quenching method. For investigated glass matrices physical properties like thickness, density and refractive indices, polaron radius etc. were measured/calculated. The investigated glasses are characterized through the X-ray diffractometer (XRD), Fourier Transform Infra-Red (FT-IR), Absorption, Emission and fluorescence lifetime analysis. The radiative properties for the optimized BPbBaLiSm10 glass have been calculated using J-O spectral intensity parameters. The luminescence spectra consist of four bands at 573, 610, 657 and 718 nm, which were assigned to 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of trivalent Sm3+ ions respectively. In the present investigated glasses, BPbBaLiSm10 glass has highest emission peak intensity for the transition 4G5/2 → 6H5/2 at 610 nm. The high values of Stimulated emission cross-section (σemi = 7.56 × 10−22 cm2), gain band width parameter (σemi x τexp = 15.25 × 10−28 cm3) and fluorescence lifetime (τexp = 0.951 ms) for 4G5/2 → 6H5/2 transition of BPbBaLiSm10 glass strongly suggesting that the present investigated BPbBaLiSm10 glass may be potential candidate for development of visible lasers and photonics display (red colour) device applications.

We report on an efficient Ho3+ and Ho3+/Nd3+ co-doped oxyfluorosilicate glasses upon excitation with an 808 nm laser diode. The detailed fluorescence have been studied under this excitation source and energy transfer mechanisms in Ho3+/Nd3+ co-doped oxyfluorosilicate glasses. The upconversion peaks at 486, 547 and 596 nm were observed in Nd3+/Ho3+ co-doped sample. The intensity of upconversion emission transitions in Ho3+ depends on the neodymium codopent concentration. These results indicate that Nd3+ ions can be potentially used as sensitizer for Ho3+ ions to stimulate the intense upconversion emission. The energy transfer mechanism between Nd3+ and Ho3+ was analyzed pursuant to the absorption spectra, upconversion spectra and the energy level structures of Nd3+ and Ho3+ ions have been briefly discussed.

A series of Er3+ ions doped tellurium calcium zinc niobium borate glasses were prepared by the melt quenching technique. The prepared samples were investigated by optical absorption and near infrared fluorescence spectroscopic studies. The obtained Judd–Ofelt intensity parameters Ωλ (λ=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from absorption spectra and their results are studied and compared with reported literature. The stark-level energies of 4I13/2 excited and 4I15/2 ground states were evaluated by using both the absorption and emission measurements. The effect of Er3+ ion concentration on the emission intensity of 4I13/2→4I15/2 transition was discussed. Intense and broad 1.53 µm infrared fluorescence is observed at 980 nm diode laser excitation. Photoluminescence (PL) and its decay behavior studies were carried out for the transition 4I13/2→4I15/2 at 1.53 µm emission. The broad emission together with higher values of the bandwidth (81 nm), stimulated emission cross-section (32.25×10−22 cm2) and lifetime (530 µs for 1.0 mol% of Er3+) of level 4I13/2 make these glasses attractive for broadband amplifiers. From the analysis of spectroscopic data, the present glass is a prospective photonic material for practical applications in the visible and NIR region.