Search

Bismuth Boro Tellurite (BiBT) glasses doped with Er3+ ions (i.e., Er3+ = 0.1, 0.5, 1.0, 1.5, 2.0, 2.5 mol %) were prepared by using melt quenching technique and their structural, optical absorption, emission and up-conversion properties were investigated using XRD, Raman, absorption, emission and decay spectral studies. The oscillator strengths measured from the absorption spectral features were subjected to Judd-Ofelt theory to understand the radiative properties possessed by the as prepared glasses. The titled glasses excited under 379 nm exhibited green luminescence at 547 nm (4S3/2 → 4I15/2). Upon pumping with a laser diode of 980 nm (NIR), a broad NIR emission at around 1572 nm (4I13/2 → 4I15/2) was observed for which stimulated emission cross-section (σse), effective band width (Δλp), gain band width (σse × Δλp) and optical gain (σse × τR) parameters were evaluated. The up-conversion luminescence shown by these glasses has been analysed to understand the utility of these glasses as up-conversion lasers. Among all the as prepared glasses, 1 mol% of Er3+ ions doped BiBT glass exhibits better radiative properties compared to other glasses. The gain cross-section of the 1 mol% of Er3+ ions doped BiBT glass was derived using absorption cross-section (σa) and emission cross-section (σe) for different values of population inversion (γ). The Decay spectral features recorded under 980 nm excitation were used to measure the experimental lifetimes (τexp) and quantum efficiencies. All the aforementioned studies revealed that the Er3+ ions doped BiBT glasses are quite suitable to fabricate optoelectronic devices in visible green and NIR regions.

Thulium (Tm3+) doped Zinc Lead Tungsten Tellurite (ZnPbWTe) glasses having the composition 5ZnO-15PbO-20WO3-(60-x)TeO2-xTm2O3 were prepared by using melt quenching technique and analysed with optical absorption, photoluminescence (PL) and PL decay spectral measurements. The absorption data was used to calculate oscillator strengths and the Judd-Ofelt (J-O) parameters. The emission spectra were recorded under 472 nm excitation exhibit intense fluorescent peaks 650 nm and 806 nm. The emission spectral data correlated with J-O theory was used to determine radiative parameters like radiative transition probability (AR), total radiative transition probability (AT), branching ratio (βR) and radiative lifetimes (τR) for the fluorescent levels of Tm3+ ions in ZnPbWTe glasses. The decay curves for the 1G4 → 3F4 transition under 472 nm excitation were investigated to calculate experimental lifetimes (τexp) and quantum efficiency (η). The σse and η reveals that ZnPbWTe glasses doped with 1 mol% of Tm3+ ions are most suitable for fabricating deep red emitting optoelectronic devices and lasers.

The analysis of MHD flow has been a concern of consideration for research scientists and engineers. In this treatise, the steady MHD flow of an incompressible and electrically conducting Casson fluid in a micro-channel with heat generation and viscous dissipation, in the presence of hydrodynamic slip and convective boundary conditions, is examined. Exact solutions of non-dimensional steady governing equations are obtained in closed form. Transient fluid velocity, temperature, entropy generation, and Bejan number are depicted by the line graphs whereas rate of heat transfer and skin-friction coefficient are computed in tabular form for pertinent flow parameters. It is established that the entropy generation rate and Bejan number increases for increasing values of the Casson parameter and heat generation parameter. In particular, the Casson parameter accelerates the skin-friction coefficient while it provides resistance to the rate of heat transfer near the channel walls. Casson fluid finds significant applications in biomechanics, polymer processing industries, and food processing.

Samarium ions doped barium lead alumino fluoro borate glasses were prepared by conventional melt quenching technique and characterized by using various spectroscopic techniques. The amorphous nature and functional groups present host glass were confirmed by XRD and FT-IR spectra respectively. From the measured oscillator strengths the Judd-Ofelt (J–O) parameters were evaluated and subsequently used to estimate various radiative properties for the prominent fluorescent levels. The PL spectra show three transitions 4G5/2→6H5/2, 6H7/2, and 6H9/2 at 565 nm, 602 nm and 650 nm in greenish yellow, reddish orange and red regions respectively. The experimental lifetimes correlated with radiative lifetimes to calculate quantum efficiency of the as prepared glasses. The CIE chromaticity coordinates measured establishes reddish orange emission from the as prepared glasses. Based on the emission cross-sections, branching ratios, quantum efficiency and CIE coordinates, it is concluded that the Sm3+ ions doped as prepared glasses are aptly suitable for reddish orange optoelectronics device applications.

The present work illustrates the optical absorption and fluorescence properties of Pr3+ ions doped single alkali and mixed alkali fluoro tungsten tellurite glasses prepared by using melt quenching technique. The prepared glasses were characterized by using absorption, excitation and photoluminescence (PL) spectral measurements. The energies of the absorption spectral features called oscillator strengths were calculated using area method and in turn used to evaluate the Judd-Ofelt (J-O) intensity parameters (Ω2, Ω4, Ω6). Such J-O parameters are used to estimate various radiative parameters such as radiative transition probabilities (AR), branching ratios (βR), and radiative lifetimes (τR) for the prominent fluorescent levels of Pr3+ ions in these glasses. The PL spectra of the as prepared glasses show three prominent peaks at wavelengths 488, 646 and 670 nm related to the transitions 3P0 → 3H4, 3P0 → 3F2 and 1D2 → 3H5 respectively for which emission cross-sections and branching ratios were evaluated. The variations in the spectral parameters with the variation of glass matrix composition have been examined in detailed. The decay profiles of the prepared glasses have been recorded to evaluate quantum efficiency of present series of glasses. From the measured branching ratios, emission cross-sections and quantum efficiency, it was concluded that the tungsten tellurite glasses added with potassium fluoride and doped with 1 mol% of Pr3+ions (TeWK glass) are quite suitable to produce visible red emission at 670 nm suitable to fabricate red luminescent devices.

A new series of Sm 3+ ions doped Alkaline-Earth Chloro Borate (AECB) glasses with compositions (25-x)CaO-5SrO-10BaCl 2 -60B 2 O 3 -xSm 2 O 3 (x = 0.1 mol%–2.5 mol%) were prepared by a conventional melt quenching technique and characterized with XRD, absorption, excitation, photoluminescence (PL) and fluorescence decay spectral measurements. From the absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω 2 , Ω 4 , Ω 6 ) have been measured. The PL spectra under 402 nm excitation show bright reddish-orange emission at 602 nm. The decay spectral profiles of 4 G 5/2 → 6 H 7/2 (602 nm) luminescence transition used to measure experimental lifetimes (τ R ). The Inokuti-Hirayama model used to understand the predominant energy transfer mechanism involved in the prepared glasses. The evaluated emission cross-sections ( σ se ), branching ratios ( β R ) and quantum efficiency (η) allows us to contemplate that the Sm 3+ ions doped AECB glasses are aptly suitable as potential gain mediums for visible reddish orange lasers pumped directly by commercially available 405 nm laser diodes.

Europium ions doped Oxy-Fluoro-Borate glass samples (OFB) were synthesized through the melt-quench mechanism. In order to analyze the lasing properties; absorption, photoluminescence (PL) excitation, PL emission, and PL decay curve spectral measurements were done. For europium ions doped OFB glasses, the Judd-Ofelt (J-O) parameters were evaluated from the PL spectra instead of absorption spectral data. The obtained J-O parameters follow the same trend Ω2>Ω4 for all the titled glasses. The PL spectra of all the glasses possess an intense peak in the reddish region at 612 nm. In europium doped OFB glasses, the concentration quenching is not observed up to 2.0 mol%. From the decay profiles, experimental lifetimes were measured and they are used to evaluate the quantum efficiency. Of all the glasses OFBEu20 glass has the highest values of quantum efficiency and stimulated emission cross-section. The evaluated CIE coordinates of these glasses also fall in the reddish region which can be confirmed through the con-focal images. Hence OFBEu20 glass is aptly considered as a good optical material for red color laser emission.

One-dimensional electrospun lead oxide nanofibers synthesized by a simple electrospinning technique. The prepared lead oxide nanofibers investigated by using TG/DTA, FTIR, Raman, X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analyzer, scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX), atomic force microscopy (AFM), Transmission electron microscopy (TEM), and impedance spectroscopy techniques. TG/DTA results confirmed the thermal behavior of the as-spun nanofibers. XRD, FTIR, and Raman spectra results, respectively, confirm the formation of pure orthorhombic crystalline phase and structural coordination of the lead oxide (β-PbO) nanofibers. The BET specific surface area of β-PbO nanofibers sample is found to be 51.23 m 2 g −1 . SEM and AFM micrographs showed the formation of β-PbO nanofibers with a diameter of 85–300 nm. The impedance measurements of lead oxide nanofibers as a function of temperature, 25–150 °C, was evaluated by analyzing the measured impedance data using the winfit software. The electrical conductivity of the lead oxide (β-PbO) nanofibers evaluated by analyzing the measured impedance data using the winfit software is found to be 5.68 × 10 −6 S cm −1 at 150 °C. Also, an activation energy (E a ) for the migration of the charge carrier evaluated from the temperature dependence of conductivity plot is found to be 0.27 eV. The temperature dependence AC conductivity of β-PbO nanofibers was evaluated using the measured impedance data and sample dimension. The observed variation of high-frequency AC conductivity attributed to the hopping electrons between the adjacent sites.

A new series of Er3+ ions doped Oxy Chloro Boro Tellurite glasses were prepared by melt-quenching method. Various spectroscopic properties were determined from absorption, excitation and photo-luminescence spectra. The Judd-Ofelt intensity parameters Ωλ(λ=2,4,6) were estimated based on absorption spectra. A strong luminescence band was observed at 1536nm under the excitation wavelength of 522nm. The gain coefficient of 1.53μm emission was estimated to probe the utility of glasses in broad band amplification technology. Inokuti-Hirayama model was employed to decay curves, to comprehend the nature of energy transfer between erbium ions. The stimulated emission cross-sections (σsec), branching ratios (βR), quantum efficiencies (η%) and gain cross-section (σsecxτR) for Er3+ ions doped OCBT glasses were evaluated and compared with other reported glass samples. Based on the highest stimulated emission cross-section, branching ratios, quantum efficiencies and gain cross-sections, it is suggested that 1mol% of Er3+ ions doped OCBT glass is more suitable for NIR region optical device applications.

In the present work, oxy chloro boro tellurite (OCBT) glasses were prepared with the composition 10SrO-(10−x)Al2O3-10BaCl2-60B2O3-10TeO2-rSm2O (where r = 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) using melt quenching technique. Several optical properties were studied after thorough analysis of absorption, excitation, photoluminescence (PL) and PL decay profiles of these glasses. Judd-Ofelt parameters evaluated from the absorption spectra are used to understand the asymmetry around the Sm3+ ions in the present reported glasses. An effort has been made to understand the PL properties of these glasses by evaluating the key parameters such as branching ratios and stimulated emission cross-sections and quantum efficiencies. In the process of understanding mutual interaction between the Sm3+ ions, Inokuti-Hirayama (I-H) method is applied. CIE color co-ordinates also measured to confirm the reddish orange emission from these glasses. From all obtained parameters, it can be suggested that OCBTSm1.0 glass is aptly suitable for reddish orange laser applications.

A set of Bismuth Borotellurite glasses (BiBT) doped with samarium (Sm3+) ions were successfully processed by a conventional melt quenching process and characterized by various well-known techniques such as EDX, absorption measurements, emission, spectral decay measurements. EDX have been used to analyze the structural properties. Physical properties like transmission factor (Toptical), reflection loss (Rloss), metallization criterion (Mcriterion), etc., were evaluated. By correlating the Judd-Ofelt (J-O) intensity parameters with emission spectral data, various radiative parameters were evaluated for the prominent fluorescent levels of Sm3+ ions arising from 4G5/2 to 6HJ (J = 5/2,7/2, 9/2). The emission cross-section, branching ratio, quantum efficiency values evaluated for the prominent emission band 4G5/2 → 6H7/2 observed at 599 nm indicates the suitability of the as prepared glasses for visible reddish-orange luminescent applications. The CIE coordinates evaluated from the emission spectral features were in consonance with the results obtained from the J-O analysis.

This paper reports on the sensitization of Er3+ ions near infrared emission (1.54 μm) using Yb3+ as a sensitizer in alkaline-earth chloro borate (AECB) glasses synthesized by using melting quenching method. The Er3+ NIR emission has been observed in the range 1450−1650 nm with intense peak at 1540 nm upon 381 nm excitation. The effect of Yb3+ ion concentration as sensitizer on NIR emission of Er3+ doped AECB glasses has been investigated in detailed using the photoluminescence excitation (PLE), PL emission and decay spectral studies. The enhancement in the NIR emission upon varying the Yb3+ doping ion concentration has been aptly elucidated through an energy level diagram. To check the suitability of these glasses for laser and fiber amplifier applications, the absorption, emission and gain cross-sections are also evaluated. Relatively higher values of absorption (σacs = 14.6 × 10−21), emission (σecs = 13.72 × 10−21 cm2) and gain cross-sections are observed for 0.5Er3+-1.5Yb3+ AECB optimized glass. The results obtained contemplates the superior nature of Er3+ and Yb3+ co-doped AECB glasses for the laser and fiber amplifier applications.

Lead Tungsten Tellurite (LTT) glasses doped with different concentrations of Tm3+ ions of composition (60−x) TeO2+25WO3+15PbF2+xTm2O3 (Here x=0.1, 0.5, 1.0, 1.5, 2.0, 2.5 mol%) were prepared by using melt quenching technique and characterized through optical absorption, photoluminescence and decay spectral studies to know the feasibility of using these glasses as luminescent devices in visible Red and NIR regions. Judd–Ofelt (J–O) theory has been applied to the optical absorption spectral profiles to calculate the J–O intensity parameters Ωλ (λ=2, 4 and 6) and consecutively used to evaluate various radiative properties such as radiative transition probability (AR), radiative lifetimes ( τ R ) and branching ratios ( β R ) for the prominent luminescent levels. The luminescence spectra for all the LTT glass samples have two intense peaks in bright red and near Infrared regions at 650 nm (1G4→3F4) and 800 nm (3H4→3H6) respectively for which effective band widths ( Δ λ P ), experimental branching ratios ( β exp ) and stimulated emission cross-sections ( σ s e ) are evaluated. The decay profiles for all the glasses are recorded to measure the quantum efficiency by coupling the radiative with experimental lifetimes. From the measured emission cross-sections, quantum efficiency and CIE chromaticity co-ordinates, it was found that 0.5 mol% of Tm3+ ions doped LTT glass is most suitable for generating bright visible Red and NIR lasers to operate at 650 and 800 nm respectively.

The organic NLO crystal for 4-Amino-5-Nitroindole was grown using slow evaporation method along with customized orthorhombic lattice formation and the crystal superiority was evaluated by recording XRD pattern. The framing of crystal structure using molecular planes was examined to find unit cell parameters. The space group (Pnam) for present organic molecular structure was assigned and the density of molecular structure in crystal geometry was measured using B3LYP/6–311++G (d,p). The electronic assisted optical activity of dielectric phase of material was tested and thereby efficiency of NLO activity was calculated. The organic composite geometry was clearly tested to find the molecular stacking and crystal density for stabilizing dielectric slabs. The mulliken charge domain displacement was traced and the parametric oscillation was studied for finding the crystal stabilization. The molecular cross-sectional scattering characteristics of base and allied bond network were studied from the vibrational analysis observation. The electrical assisted electronic process was examined for determining NLO activity to for test ultra-high frequency amplification. The CT complex was identified and it also found to be belonging to indole ring. The electronic and protonic depletion space was calculated from the result of molecular dipole moment and the static charge rigidity was acknowledged. The NBMO profile was keenly grafted and the transitional energy was measured at every consumed electronic energy bands. The vibrational circular dichroic enantiomer image at all vibrational regions was drafted and the sequential pattern of transmission and absorption was verified by obtained peak intensity.

Dy3+ ions doped phosphate glasses were prepared using sudden melt quench method. The studies like XRD, FT-IR, optical absorption, photoluminescence excitation, photoluminescence (PL), and PL decay were conducted to understand the spectroscopic properties. The Judd-Ofelt (J-O) parameters evaluated from absorption spectral features were employed to evaluate various radiative parameters of Dy3+ ions in phosphate glasses. Two intense bands were observed in PL spectra, in blue and yellow regions under 387 nm excitation. The emission spectra indicate concentration quenching for phosphate glass with 1 mol% of Dy3+ ions, which may be ascribed to dipole-dipole interactions between Dy3+ ions (Dexter theory). These PL spectral features were also used to estimate Y/B intensity ratio, CIE-chromaticity coordinates to understand the utility of prepared glasses in Lasers. The stimulated emission cross-sections, branching ratios, quantum efficiencies and CIE-color coordinates evaluated to validate the suitability of the prepared glasses for yellow laser applications.

This paper describes the preparation and characterization of various concentrations of Nd3+ doped B2O3–BaF2–PbF2–Al2O3 (BaPbAlFB) glasses in detailed. The glasses used in the present work are synthesized by using melt quenching process and characterized by measuring the absorption, photoluminescence (PL) and PL decay spectral profiles. The energies of the absorption spectral profiles called oscillator strengths are evaluated from the absorption spectra and subjected to Judd-Ofelt (J-O) theory to evaluate the J-O intensity parameters using least squares fit method. Under 808 nm diode laser excitation, the BaPbAlFBNd glasses exhibit three emission bands at near-infrared region around 887, 1063, 1336 nm from 4F3/2 → 4I9/2, 4I11/2 and 4I13/2 radiative transitions respectively. Among the three emissions, the one observed at 1063 nm is found to be more intense relatively. The lifetime of 4F3/2 transition has been estimated experimentally through decay measurements recorded under 808 nm excitation wavelength. Among all the BaPbAlFB glasses investigated, the one with 1.0 mol% of Nd3+ ions is showing relatively high fluorescence quantum efficiency. The measured saturation intensity (IS) values shows relatively the low threshold values. The obtained results endorsed the potentiality of BaPbAlFBNd1.0 glass for the fabrication of fiber amplifiers and solid-state lasers that can act in NIR region at 1063 nm wavelength.

The melt quenching process is adopted in fabricating the glass system 10Li2O-60B2O3-(30-x)P2O5: xCuO (0 ≤ x ≤ 2.5 mol%, where x = 0, 0.5, 1.0, 1.5, 2.0 and 2.5). The specimens are analyzed by X-ray diffraction (XRD), optical absorption, emission spectra, electron spin resonance (ESR) spectra, Fourier transform infrared (FTIR) studies and dielectric investigations. XRD reveals the glassy temperament of specimens. Optical absorption spectra exhibited bands due to Cu2+ ions. ESR spectra exhibited the peaks due to copper ions occupying the octahedral positions. Spin-Hamiltonian parameters of glasses judged the escalating ionic character of specimens with a rise in content of dopant. FTIR displayed traditional bands corresponding to borate and phosphate groups. Dielectric parameters like dielectric constant (e′), loss (tanδ) and a.c. conductivity (σac) increase with a rise in the quantity of dopant. All results brace that specimen C25 (sample doped with 2.5 mol% of CuO) has the highest semiconducting nature.

Optically transparent Barium Lead Alumino Fluoro Borate (BaPbAlFB) glasses doped with different concentrations of Ho3+ ions were prepared by using melt quench technique. Raman spectral studies were conducted to understand the structural groups present in the as prepared glasses at room temperature. Spectroscopic investigations such as optical absorption, excitation, emission and decay measurements were conducted to understand the visible photoluminescence (PL) and lasing potentialities of BaPbAlFB glasses. The bonding parameters (δ) estimated from the absorption spectral features were used to understand the nature of bonding between Ho3+ ions and the surrounding ligands. The Urbach energy values estimated from the absorption spectral data are used to verify the amorphous nature of the present glass system. The Judd-Ofelt (J-O) theory has been applied to the measured oscillator strengths of the absorption spectral features to estimate the best fit J-O parameters (Ωλ, λ = 2, 4, and 6) useful in evaluating various radiative parameters for the prominent fluorescent levels of Ho3+ ions in BaPbAlFB glasses. The experimental lifetimes (τexp) are found to be decreasing with increase in Ho3+ ion concentration owing to energy transfer. The quantum efficiency (η) of Ho3+ ions doped BaPbAlFB glasses were estimated by correlating the experimental lifetimes (τexp) with the radiative lifetimes (τR). The strong visible emission, large stimulated emission cross-section (σse), high branching ratio (βR) and relatively good quantum efficiency (η) obtained for 5S2→ 5I8 (green) transition of 1 mol% of Ho3+ ions doped BaPbAlFB glass reveals its suitability in designing and developing visible green lasers.

Olivine LiMPO4 (M = Co and Ni) nanoparticles have been synthesized by the polyvinylpyrrolidone (PVP) assisted polyol method and adopted the resin coating process for carbon coating on the surface of the nanoparticles. The X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy studies confirmed the phase and structural co-ordination of bare and carbon-coated LiMPO4 (M = Co and Ni) nanoparticles, respectively. The formation of uniform carbon layer of nanometer-measured thickness over nanoparticles is confirmed by the high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectroscopy (EDS). Wagner’s polarization study explains an improved electronic transport number (t e) for carbon-coated LiMPO4 (M = Co and Ni) cathodes as compared to bare samples. The electrochemical study of the Li-ion cells shows the first cycle discharge capacities of 180 and 97 mAh/g at 0.1 C for the cathodes LiCoPO4/C and LiNiPO4/C, respectively, which is an improvement of 21.2 and 25.8 % as compared to bare samples. The enhancement of electrochemical performance of the cells is attributed to the improved electronic properties of cathode materials due to the presence of carbon on the surface of nanoparticles.

Er3+ doped Zinc Alumino Bismuth Borate (ZnAlBiB) glasses with composition 20ZnO+10Al2O3+(10−x)Bi2O3+60B2O3+xEr2O3 (where x=0.1, 0.5, 1.0 and 2.0 mol%) were prepared by using a melt quenching technique to study their luminescence efficiency in different regions of electromagnetic spectrum using absorption, emission, up-conversion and time resolved photoluminescence spectral studies at room temperature. The Judd–Ofelt (JO) parameters evaluated by applying JO theory to the absorption spectra of Er3+ doped ZnAlBiB glasses were used to calculate the radiative properties such as transition probability (AR), Branching ratios (βR), radiative lifetimes (τR), stimulated emission cross-section ( σ s e ), gain band width ( σ s e × Δ λ P ) and optical gain ( σ se × τ R ) parameters for the prominent luminescent levels of Er3+. Visible and near infra-red (NIR) emission spectra have been recorded by exciting the glass samples at 486 nm and 980 nm respectively. Quantum efficiency (η) values for the prepared glasses were evaluated from the decay curves recorded for the NIR transition 4I13/2→4I15/2. The up-conversion luminescence shown by these glasses were recorded and analysed to understand utility of these glasses as up-conversion lasers by exciting them with 980 nm laser diode. The visible, up-conversion and NIR luminescence studies indicate that Er3+ ions doped ZnAlBiB glasses are aptly suitable for solid state lasers and optical amplifiers.

Lead Tungsten Tellurite (LTT) glasses doped with different concentrations of Ho 3+ ions have been synthesized using the melt quenching method and characterized to understand their visible emission characteristic features using optical absorption and photoluminescence spectral studies. The Judd–Ofelt (JO) parameters measured from the absorption spectral features were used to evaluate radiative properties such as transition probability ( A R ), branching ratio ( β R ) and radiative lifetimes ( τ R ) for the prominent fluorescent levels of Ho 3+ ions in LTT glasses. The photoluminescence spectra recorded for all the Ho 3+ doped LTT glasses at an excitation wavelength 452 nm gives three prominent emission transitions 5 F 4 → 5 I 8 , 5 F 5 → 5 I 8 and 5 F 4 → 5 I 7 , of which 5 F 4 → 5 I 8 observed in visible green region (546 nm) is relatively more intense than the other two transitions. The intensity of 5 F 4 → 5 I 8 emission transition in these glasses increases up to 1 mol% of Ho 3+ ions and beyond concentration quenching is observed. Branching ratios ( β R ) and emission cross-sections ( σ se ) were evaluated for the intense emission transition 5 F 4 → 5 I 8 in these glasses to understand the luminescence efficiency in visible green region (546 nm). The CIE chromaticity coordinates were also evaluated in order to understand the suitability of these glasses for visible luminescence. From the measured emission cross-sections and CIE coordinates, it was found that 1 mol% of Ho 3+ ions in LTT glasses are most suitable for visible green luminescence in principle.

Nanocrystalline Scheelite type Dy doped AMoO{sub 4} [where A = Ba, Sr and Ca] samples were prepared by acrylamide assisted sol–gel process and characterized by XRD, FT-Raman, FTIR, SEM and photoluminescence (PL). PL of undoped sample shows blue/green emission in CaMoO{sub 4} and SrMoO{sub 4} but multicolour visible emission leading to near white light in BaMoO{sub 4} nanoparticles; the origin of which is explained. It was observed that on doping 0.5 mol% of Dy{sup 3+} in molybdate samples complete energy transfer takes place in case of SrMoO{sub 4} and BaMoO{sub 4}, but host contributed substantially in Dy doped BaMoO{sub 4} sample, resulting in biexponential decay. It was also observed that symmetry around Dy{sup 3+} decreases as the size of alkaline earth ion increases. Due to combined blue, yellow and red colour emission in dysprosium doped sample; all samples showed near white light emission under UV and near UV excitation.

Nanocrystalline BaMoO 4 samples doped with varying Dy 3+ content were prepared by acrylamide assisted sol–gel combustion process. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform Raman spectroscopy (FT-Raman), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and photoluminescence (PL) techniques. The crystalline phase and structure of all the Dy 3+ doped BaMoO 4 prepared samples were confirmed from the analysis of the obtained results of XRD, FT-Raman and FTIR. The average crystallite sizes of all the prepared samples, calculated using Scherrer׳s formula and XRD data, were found to be less than 100 nm. Microstructures of all the prepared Dy 3+ doped BaMoO 4 samples were analyzed from the obtained SEM micrographs. Excitation, emission and lifetime spectroscopic studies of undoped and Dy 3+ doped BaMoO 4 were carried out. Effect of concentration of Dy 3+ on the luminescence properties of the prepared phosphors viz. emission intensity and PL decay, was also investigated. Based on critical distance calculation, mechanism for concentration quenching was proposed. Undoped sample was found to give reddish blue emission, whereas doped samples showed yellowish white emission.

Oxy-fluoroborate (OFB) glasses doped with different concentrations of Sm 3+ ions have been prepared using conventional melt quenching technique and characterised for their lasing potentialities using spectroscopic techniques such as FTIR, optical absorption, emission and emission decay measurements. The FTIR spectrum has been recorded to determine the various functional groups present in the OFB base glass. From the absorption spectra, the bonding parameters ( δ ) were evaluated to find the bonding nature present between Sm 3+ ions with its neighbouring ligands. The Judd–Ofelt intensity (J–O) parameters ( Ω λ , where λ =2, 4, and 6), measured from the experimental oscillator strengths of the absorption spectral futures, are used to evaluate the radiative parameters for the fluorescent transitions 4 G 5/2 → 6 H 5/2 , 4 G 5/2 → 6 H 7/2 , 4 G 5/2 → 6 H 9/2 and 4 G 5/2 → 6 H 11/2 of Sm 3+ ions in OFB glasses. The asymmetric ratio has been evaluated to understand the local disorder of Sm 3+ ions in the glass network. The experimental lifetimes ( τ exp ) measured from the decay curves are coupled with radiative lifetimes ( τ rad ) to measure quantum efficiency ( η ) of the prepared glasses. The experimental lifetimes ( τ exp ) for 4 G 5/2 emission state decrease with increase in Sm 3+ ion concentration due to energy transfer. In order to elucidate the nature of energy transfer mechanism, the non-exponential decay curves are well fitted to the Inokuti–Hirayama model for S =6, which indicates that the energy transfer mechanism is of dipole–dipole type. The branching ratio ( β R ), stimulated emission cross-section ( σ se ) and quantum efficiency ( η ) values measured for the most intense emission transition 4 G 5/2 → 6 H 7/2 (598 nm) optimise the concentration of Sm 3+ ions as 1 mol% to produce bright visible orange lasing emission from these OFB glasses.

Scheelite type BaMoO4 nanofibers were prepared by using acrylamide assisted sol–gel process and electrospinning technique. The prepared Scheelite BaMoO4 nanofibers were characterized by using TG/DTA, XRD, FTIR, FT-Raman and SEM–EDX techniques. Thermal behavior, crystalline phase and structure of the prepared BaMoO4 nanofibers samples were confirmed from the analysis of the obtained results of TG/DTA, XRD, FTIR and FT-Raman respectively. SEM micrographs along with EDX showed the formation of one dimensional (1D) nanofibers 100–350 nm diameters and existence of Ba, Mo and O elements in the BaMoO4 nanofibers sample. The electrical conductivity of BaMoO4 nanofibers as a function of temperature 200–400 °C under air was evaluated by analyzing the measured impedance data using the winfit software. The newly prepared Scheelite type BaMoO4 nanofibers showed electrical conductivity of 0.92 × 10−3 S/cm at 400 °C.

The Alkaline-Earth Boro Tellurite (AEBT) glasses doped with different concentrations of Erbium (Er3+) ions were prepared by sudden melt quenching technique. The prepared samples were characterized by optical absorption, visible, Up-Conversion (UC), near-infrared (NIR) luminescence and luminescence decay to understand their luminescence properties. The Judd-Ofelt (J-O) intensity parameters (Ωλ, λ = 2, 4, 6) were calculated from the absorption spectra. Different radiative properties such as total radiative transition probability (AT), radiative lifetime (τR), radiative branching ratios (βR), stimulated emission cross-section (σse), effective bandwidth (Δλp), gain bandwidth (σse x Δλp) and optical gain (σse x τR) for Er3+ ions in the titled glasses were estimated. The Decay spectral curves for the 4I13/2 level of Er3+ ions in AEBT glasses were recorded under 980 nm excitation for 1574 nm emission. The obtained results reveal that the titled glasses are suitable for the optical devices like solid state lasers and fiber amplifiers.

Bioreduction mechanism of Tecoma stans leaf extract for the extracellular synthesis of silver nanoparticles was investigated using ultraviolet-visible spectroscopy (UV–vis). Nanostructure of the bio synthesized silver particles was confirmed by transmission electron microscopic (TEM) analysis. Crystalline cubic phase of the synthesized silver nanoparticles was confirmed by X-ray diffraction (XRD) technique. Observed rapid reduction behavior of Tecoma stans leaf extract was effectively explored for the functionalization of single-walled carbon nanotubes (SWCNT) with silver nanoparticles. Scanning electron microscopic (SEM) and TEM characterization confirmed the functionalization of single walled carbon nanotubes with the silver nanoparticles and the size of silver nanoparticles were found to be in the range of ∼5–10 nm.

Lithium cobalt phosphate (LiCoPO4) nanoparticles were synthesized using modified polyol process. Shape and size of LiCoPO4 nanoparticles were controlled by using poly (vinylpyrrolidone) (PVP) stabilizer. Coating of carbon over the LiCoPO4 nanoparticles was done using the resin coating process to enhance its conductivity. XRD and FTIR results respectively confirm the crystalline phase and structure of pure and carbon coated LiCoPO4 nanoparticles. SEM-EDX results confirm size and shape and also the presence of carbon over LiCoPO4 nanoparticles. Electrical conductivity of pure and carbon coated LiCoPO4 nanoparticles were evaluated by analyzing the measured impedance data using the win fit software. More than three orders of conductivity enhancement was observed in carbon coated LiCoPO4 nanoparticles when compared to pure ones. Further, transport properties like temperature dependence conductivity, AC conductivity, dielectric constant and electric modulus studies were made to find out the bulk and relaxation properties of LiCoPO4 nanoparticles.

In situ base catalyst assisted sol–gel process is used for the synthesis of nanocrystalline CoFe2O4 deposition on SiO2 particles. The SiO2 particles were prepared using base catalyst assisted sol–gel process and the consecutive formation and deposition of nanocrystalline CoFe2O4 on SiO2 particles was monitored using Powder X ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric And Differential Thermal Analysis (TG/DTA), Scanning Electron Microscopy and Energy Dispersive X ray Spectroscopy (SEM–EDS) and High Resolution Transmission Electron Microscopy (HRTEM). The crystallite size of CoFe2O4 is calculated using Scherrer’s formula and it is found to be 8 nm. The HRTEM images and selective area electron diffraction (SAED) results confirmed the formation of nanocrystalline CoFe2O4 particles deposited over SiO2 spheres.

Nanocrystalline ZrO2 powders have been prepared using acrylamide assisted polymeric citrate combustion (autoignition) route. Process parameters (i.e., total metal ions to citric acid ratio) were varied for the formation of polymeric resin in order to obtain the final product with desired properties (organic free, smaller crystallite size, etc.). The effect of three different citric acid amounts in the formation of nanocrystalline ZrO2 powder was investigated using FTIR, XRD, TG/DTA and SEM-EDS, respectively, to identify the structural coordination, phase, thermal behavior and microstructure of the polymeric intermediates as well as the final ZrO2 powders. Organic free ZrO2 powder with two different phases of metastable t-ZrO2 and m-ZrO2 were prepared by calcining the polymeric intermediates at 600 °C. The lowest crystallite was found to be 18 and 16 nm, respectively, for the t-ZrO2 and m-ZrO2 phases prepared with total metal ions to citric acid ratio of 1:3.

The ternary 10% Li 2 O + 90% ( x As 2 O 5 + (1 − x ) SiO 2 ) ( x = 0.025, 0.05, 0.075 and 0.1) (LAS) glassy system with different compositions were prepared using sol–gel technique. All the prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry techniques. The observed peak-free XRD patterns confirm the amorphous phase of the prepared LAS compounds. Structural coordination of LAS glassy samples was confirmed by Fourier transform infrared spectroscopy. Thermal behavior of the glassy samples was characterized by differential scanning calorimetry. Bulk conductivity of all the LAS glassy samples was calculated by analyzing the impedance data measured at different temperatures. Activation energy ( E a ) is evaluated from the log σT vs. 1000/ T plot and it is found to be 0.837 eV.

Nanocrystalline LiCoO 2 powders were synthesized by combustion process using three different ammonium carboxylates named ammonium acetate (AA), ammonium citrate (AC) and ammonium tartarate (AT) as fuels and metal nitrates as the source of metal ions as well as oxidants. Effect of three different ammonium carboxylates on the synthesis of nanocrystalline LiCoO 2 powders was investigated through FTIR, XRD, TG/DTA and SEM techniques. FTIR and XRD analysis confirmed that the LiCoO 2 phase could obtain by calcining the polymeric intermediates at 450 °C for 12 h. Among the three different fuels, ammonium citrate assisted combustion process exhibited the formation of organic free phase pure nanocrystalline LiCoO 2 powders. The average crystallite size of the LiCoO 2 powder prepared at 450 °C for 12 h by ammonium citrate assisted process is found to be 24 nm.

Uniform spheres of nanocrystallite size cuprous oxide particles have been prepared by a simple polyol process using cupric nitrate as a precursor in ethylene glycol. As synthesized compound was dried at 333 K in a vacuum oven and characterized by XRD, FT-IR and SEM techniques. The crystallite size of the cuprous oxide calculated from Scherer's formula was found to be ∼11 nm.

Nanocrystalline LiMn 2 O 4 powders were synthesized by Pechini process using metal nitrates/acetates as metal ion sources, citric acid and polyethylene glycol-400. Effect of calcining temperature on the electrochemical performance of nanocrystalline LiMn 2 O 4 powders was investigated. Thermal decomposition of polymeric intermediate was investigated through DSC thermogram. FT-IR was used to identify the structural coordination of as prepared and calcined polymeric intermediate. The phase of the synthesized LiMn 2 O 4 powder was confirmed by comparing the obtained XRD patterns with the JCPDS standard. CV and battery cyclic studies showed that the better electrochemical activity for LiMn 2 O 4 compound, prepared at 750 °C, with a discharge capacity of about 110 mAh g − 1 .

Lithium samariumsilicate (LSS) was synthesized using a sol–gel process. The formation of crystalline phase and structure of the LSS compound were obtained by monitoring the dried gel heat treated, at various temperatures, from amorphous to crystalline growth through XRD and FTIR measurements. Bulk conductivity of the LSS sample was calculated from the analyzed impedance data, at different temperatures, using Boukamp equivalent circuit software. The activation energy (Ea) obtained from the slope of log σT versus 1000T−1 was 0.55 eV. ac conductivity was calculated using the measured impedance data at different temperatures and it was analyzed using Jonscher's Universal Power Law (JUP). The evaluated power law exponent s exhibits a non-linear behavior with temperature. The ion relaxation behavior was explained with the diffusion controlled relaxation model. Electric modulus (M* = M′ + iM″) was calculated from impedance data, which exhibits non-Lorentzian type peak with a relaxation frequency, ω0, and a tail extending in the region of shorter relaxation time. The peak frequency ω0 shifts towards the higher frequency with increase in temperature.

Silverarsenotellurite (SAT), silverphosphotellurite (SPT) and silvervanadotellurite (SVT) quaternary glass systems were prepared with various formers compositions by a melt quenching method. Glass nature, glass transition temperature (Tg) and structure of the prepared glasses were identified respectively by X-ray diffraction (XRD), differential scanning calorimetric (DSC) and Fourier transform infrared (FT-IR) technique. Electrical conductivity studies were carried out by impedance measurement in the frequency range 40 Hz to 100 KHz at different temperatures for all three sets of AgI–Ag2O–[TeO2–M2O5] (M2O5 = As2O5, P2O5, V2O5) glasses. The high conducting compositions of SAT, SPT and SVT glass samples were fixed from the results of total conductivity (σt). Electronic conductivity (σe) studies were made on high conducting composition of each glass system by Wagner's polarization method. Total current (it) is due to ion and electron. Electronic current (ie) due to electron were estimated through mobility studies. Ionic conductivity (σi) and ionic current (ii) were calculated respectively using the conductivity (σt and σe) and current (it and ie) results for the SAT, SPT and SVT glasses. Transport numbers due to ion (ti) and electron (te) were calculated using the conductivity and mobility results for each glass system. The high conducting composition of the SAT, SPT and SVT glasses were used as solid electrolytes with silver metal as an anode and iodine:graphite (I:C) as a cathode for the fabrication of solid state batteries (SSBs). All the fabricated batteries were characterized by measuring the open circuit voltage (OCV) and polarization properties and estimated the batteries performances.

Effect of different ethylene glycol (ethylene glycol, polyethylene glycol-400 and polyethylene glycol-4000) precursors on the Pechini process for the synthesis of nano-crystalline LiNi 0.5 Co 0.5 VO 4 powders was investigated. The structural coordination of as-prepared and calcined polymeric intermediates was investigated by FTIR analysis. Thermal behavior of the polymeric intermediates was studied by DSC thermograms. Effect of different ethylene glycols on the microstructure of polymeric intermediates was identified by SEM analysis. The inverse spinel phase of the obtained LiNi 0.5 Co 0.5 VO 4 powders was confirmed by comparing the X-ray diffraction spectra with JCPDS data and the crystallite size was calculated using XRD data and Scherrer's formula. The lowest crystallite size was found to be 49 nm for the calcined polymeric intermediate, at 450 °C for 12 h, prepared with ethylene glycol (EG).

Lithium phosphoborosilicate (LPBS) glasses were synthesized through the sol–gel process by varying nitric acid concentrations as a catalyst. The sol–gel process was monitored through XRD and DSC to optimize the LPBS glass forming treatment. Characterization of LPBS glasses was conducted using XRD, FTIR and DSC techniques. Impedance measurements were carried out at different temperatures on LPBS samples synthesized by sol–gel process with various nitric acid concentrations and impedance data were analyzed using Boukamp equivalent circuit software. The conductivity of LPBS samples was calculated from analyzed impedance data and it was found that sample synthesized with 2.5 N nitric acid concentration showed the high conductivity σ = 2.28(±0.02) × 10 −7 S cm −1 at 443 K. Activation energy ( E a ) is obtained from Arrhenius plots of dc conductivity and it is found to be 0.39 (±0.02) eV for the high conductance sample. Ac conductivity data were analyzed using Jonscher’s power law (JPL) and the power law exponent ( s ) exhibits a low s value for high conducting LPBS sample and a non-linear behavior with temperature. The electric modulus data were fitted with Kohlraush–William–Watts (KWW) stretched exponential function and modulus formalism is used to study the ionic relaxation behavior at different temperatures in LPBS glasses synthesized with varying nitric acid concentrations.

Glasses of lithium borosilicate (LBS) were synthesized by sol–gel process with various concentrations ( x = 0.01, 0.1, 1.0, 2.5 and 5 N) of nitric acid as a catalyst. LBS samples glass forming temperatures were monitor and optimized through XRD studies at different stages from gel to glass and to multicrystalline phases. XRD, FTIR and DSC techniques were used in the characterization of the LBS samples. Impedance measurements were made on LBS glasses, heat-treated at 698 K, synthesized with various concentrations of nitric acid at different temperatures and data were analyzed using Boukamp equivalent circuit software. The bulk conductivity was calculated from the analysis of impedance data and it is found that LBS glass synthesized with 2.5 N nitric acid concentration showed high conductivity σ = 1.45 (±0.02) × 10 −7 S cm −1 at 443 K. The activation energy ( E a ) was obtained from the slopes of log( σT ) versus 1000/ T plot in the region of 443–613 K and it is found to be 0.51 ± 0.03 eV for high conducting ( x = 2.5 N) LBS glass. The conductivity variations with LBS glasses synthesized with various concentrations of nitric acid as a catalyst is explained based on conductivity expression. AC conductivity were calculated from impedance data and analyzed using Jonscher's power law (JPL) exponent ( s ) for LBS glasses synthesized under various concentrations of nitric acid. The power law exponent s is found to be non-linear with the concentrations of nitric acid used in the synthesis of LBS glasses.

Quaternary silvervanadotellurite (SVT) glasses of various formers compositions ( x ) 60%AgI-26.67%Ag 2 O-13.33%[(1− x )V 2 O 5 +( x )TeO 2 ]; x = 0.0–1.0 in steps of 0.1 were prepared by a melt quenching technique. All the prepared SVT glasses were characterized by X-ray diffraction, FTIR and DSC measurements to confirm the glassy/amorphous nature, incorporation of tellurite in vanadium oxide glassy matrix and their glass transition temperature ( T g ), respectively. Complex impedance measurements were made at room temperature (RT) as well as low temperatures (99–242 K) on SVT glasses and impedance data were analyzed using the Boukamp equivalent circuit software to obtain conductivity at each temperature. Low temperatures conductivity studies were made only for the high conducting composition ( x = 0.6) of SVT glasses. Activation energy ( E a ) is obtained from Arrhenius plots of temperature dependent dc conductivity and it is found to be 0.25 eV for high conducting SVT glass. The ac conductivity was calculated using the impedance data of SVT glass measured at low temperatures and analyzed with Jonscher’s Universal Power law (JUP). The obtained power law exponent s for the SVT glass was found to exhibit a non-linear behavior with temperature and its nature of ion relaxation was explained using the DCR model. The dielectric and electric modulus ( M ∗ = M ′ + iM ″) data was calculated using impedance data for the x = 0.6 composition of SVT glass measured at low temperatures.

Nano-crystalline nickel ferrite (NiFe2O4) was synthesized using combustion process with metal nitrates as Ni and Fe ion sources and polyacrylic acid (PAA) as a chelating agent. The effect of ethylene glycol (EG) addition to polyacrylic acid on the synthesis of nano-crystalline NiFe2O4 powders was investigated through DSC, FTIR, SEM and XRD measurements. Thermal behavior, structural coordination, microstructure and crystalline phase formation of as prepared and also calcined polymeric intermediates were, respectively, obtained from the analysis of DSC, FTIR, SEM and XRD results. The crystallite size was calculated using XRD data and Scherrer's formula. The smallest crystallite size is found to be 14 nm for the phase pure NiFe2O4 powder obtained from the polymeric intermediates, calcined at 450 °C for 12 h, synthesized by PAA based gel combustion route with the total metal ions to EG ratio (M/EG) of 1:0.5.

Densified xerogels of lithium borosilicate (LBS) were synthesized through sol–gel process by varying modifier to formers (m/f) ratios. XRD and FTIR spectra were recorded for dried LBS gel samples heat-treated at different temperatures and the gel to glass to crystalline changes were studied. Also, all LBS samples were characterized by XRD, FTIR and DSC techniques. Impedance measurements were made on all LBS samples at different temperatures and the impedance data were analyzed using Boukamp equivalent circuit software. Conductivity of each m/f ratios of LBS samples were calculated from the analyzed impedance data and 20% Li2O–80% [0.2 B2O3 + 0.8 SiO2] composition showed the best conductivity σ = 8.83 (±0.02) × 10−8 Scm−1 at 443 K. The activation energy (Ea) is obtained from the temperature dependent of conductivity data fitted to Arrhenius equation and it is found to be 0.64 eV (±0.02). The observed variation of conductivity with m/f ratios of LBS samples was explained using weak electrolyte model.

Glycerol assisted gel combustion route (GGCR) was used for the synthesis of nano-crystalline inverse spinel LiNiVO 4 powders, with metal nitrates, citric acid and glycerol for three different total metal ions to glycerol ratios (M/G) as 1:1, 1:2 and 1:3. In this study, the effect of total metal ion to glycerol ratio on the formation of the nano-crystalline LiNiVO 4 phase was investigated and discussed. The thermal behavior and structural coordination of the as prepared as well as the calcined polymeric intermediates at different temperatures were investigated, respectively, using the DSC and FTIR measurements. The microstructure of the polymeric intermediates was identified by taking the scanning electron microscopy (SEM) pictures. The formation of the inverse spinel LiNiVO 4 phase, obtained from the calcined intermediates, was confirmed by comparing the observed X-ray diffraction spectra with the respective JCPDS standard. The crystallite size was calculated using the Scherrer's formula and the smallest crystallite size of 39 nm was observed for the LiNiVO 4 powders obtained from the polymeric intermediate, calcined at 450 °C for 12 h, synthesized using the GGCR with M/G=1:1.

Lithium borosilicate (LBS) glasses of different modifier to formers ( m / f ) ratios were synthesized through sol–gel process. Structural characterisation of LBS glasses were made using XRD, FTIR and DSC techniques. XRD pattern of LBS samples showed amorphous phase for gels heat treated between 573 and 698 K and further heat treatment above 698 K showed the formation of crystalline multiphases. FTIR spectra for dried LBS gels between 338 and 443 K showed the presence of hydroxyl group on the surface of silicate and borates matrix and on heat treatment, the FTIR spectra revealed the formation of silicate and borate linkages in LBS glassy matrix. DSC curve confirmed the presence of adsorbed water molecules in LBS glassy matrix. Impedance measurements were carried out on LBS samples of different m / f ratios as a function of temperature and data were analyzed using Boukamp equivalent circuit software. The conductivity of LBS glasses at different temperatures was calculated from analyzed impedance data. Activation energy ( E a ) is obtained from Arrhenius plots of the dc conductivity and it is found to be 0.64 (±0.02) eV for high conducting sample. ac conductivity is calculated from impedance data and analyzed using Jonscher's power law (JPL) exponent (s) for m / f ratios of LBS samples at different temperatures. The power law exponent s of LBS glasses exhibited a non-linear behavior with temperature. The electric modulus data were fitted with Kohlraush–William–Watts (KWW) stretched exponential function and the modulus formalism is used to study the ionic relaxation behavior in LBS samples.