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Abstract: Optical properties of a LaAlO3 single crystal doped with erbium were examined. The crystal was grown by the Czochralski method; absorption and emission spectra were measured at room and at low temperature. Decay times of main luminescence transitions were measured at 297 and 10K. Judd–Ofelt analysis was applied to calculate the oscillator strengths, radiative transitions and branching ratios. The values of the omega parameters are: Ω2 =0.962, Ω4 =0.652, Ω6 =0.352 (all Ω t values are in 10−20 cm2). RMS deviation was found to be 16.5×10−8. Emission cross-sections of the 4I13/2 → 4I15/2 and 4S3/2 → 4I15/2 were calculated. The gain of the possible 4I13/2 → 4I15/2 stimulated emission was determined. [Copyright &y& Elsevier]

Abstract: The spectroscopic properties of Er2O3-doped PbO–Ga2O3–GeO2 glasses were investigated. The measured lifetime and stimulated emission cross-section of the 4I13/2 level were 4.73±0.05ms and 6.8×10−21 cm2, respectively. The measured lifetime and stimulated emission cross-section were 0.31±0.02ms and 1.9×10−21 cm2 for the 4I11/2 level, respectively. The lifetimes of 4I13/2 levels were almost constant up to the Er3+ concentration of ∼1.3×1020 cm−3. The constant α (6) for energy migration of the 4I13/2 level was considerably higher than that of the 4I11/2 level. On the other hand, the coefficient of cooperative upconversion for the 4I13/2 level was 104 times smaller than that for the 4I11/2 level at the concentration of 2.57×1020 cm−3. These results suggest that the contribution of the migration-accelerated energy transfer among Er3+ ions to the non-radiative transition from the 4I13/2 level is larger than that from the 4I11/2 level, whereas the non-radiative transition from the 4I11/2 level is mainly due to the cooperative upconversion effect via 4I11/2:4I11/2 → 4 F7/2:4I15/2 process. The obtained results also indicate that the PbO–Ga2O3–GeO2 glass is a good candidate for short optical fiber amplifiers. [Copyright &y& Elsevier]

Polycrystalline glass-ceramic CaSiO 3 doped with Eu3+ ions was obtained by devitrification. The analysis of the photoluminescent characteristics of the obtained glass-ceramic is carried out. It was found that as a result of the devitrification of CaSiO 3 , two phases are formed, identified as pseudowollastonite (β-CaSiO 3) as the dominant phase together with a small percentage of tridymite (SiO 2). The UV–Vis optical absorption of Eu3+-doped CaSiO 3 was performed using a UV–Vis spectrophotometer. The main objective of this work was to study the effect of the pulsed corpuscular action of electrons accelerated in a field of 130 keV on energy transitions in the Eu3+ ion. It is found that, upon steady-state excitation of the photoluminescent signal in the PLE spectra of unirradiated samples at wavelengths below 300 nm, two broad excitation peaks are displayed, possibly associated with O − Eu and O − Si CT transitions. Above 300 nm the characteristic excitation band from 7F 0 ground state to 5H j , 5D 4 , 5G j , 5L 6 , 5D 3 , and 5D 2 states of the Eu3+ ions are shown. It was found that, as a result of exposure to an electron beam in the photoluminescence spectra of europium, a redistribution of the relative intensities of the 5D 0 → 7F 2 and 5D 0 → 7F 1 transitions occurs. The calculation of the asymmetry ratio of these transitions showed values for an unirradiated sample R 21 = 2.06 and irradiated R 21 = 2.52, which indicates a decrease in the symmetry of the crystal field around Eu3+ ions after irradiation. Several reasons for the decrease in the relative intensity of the Eu3+ luminescence signal after electron irradiation, caused by the effect of electrization of the material, intrinsic defects of the matrix, and inhomogeneous phase composition, are discussed. • Eu doped glass-ceramic CaSiO 3 has been produced by the devitrification method. • Absorption band is due to (O-Si) LMCT and SiOHC or NBOHC centers. • Excitation peaks at 227.5 and 244 nm could be associated with O−Eu and O−Si CT transitions, respectively. • There are several possible reasons that promote PL quenching after electron irradiation. • The increase of the R 21 ratio after electron irradiation indicates a luminescent optimization. [ABSTRACT FROM AUTHOR]

The europium ion (Eu3+) activated lithium zirconium phosphate (Li 2 Zr(PO 4) 2) phosphor samples have been synthesized by conventional solid state reaction (SSR) method at high temperature. The obtained phosphor samples crystallize in the hexagonal phase with space group R3C. Photoluminescence (PL) excitation and emission spectra have been recorded and optimum concentration was found to be 2 mol%. In the PL spectra of the synthesized phosphors, a characteristic emission peak observed at 594 nm which is ascribed to the magnetic dipole (MD) dominant transition 5D 0 →7F 1. The colorimetric parameters CCT and CIE R a values are estimated by CIE chromaticity co-ordinates. Judd-Ofelt (J-O) intensity parameters obtained from emission spectra have been used to evaluate the local site symmetry around Eu3+ ions. The J-O parameters have also been used to calculate the radiative transition probability, branching ratio and radiative lifetime. The gain bandwidth, optical gain parameter and stimulated emission cross-section are also investigated. Thermoluminescence (TL) properties of prepared phosphor have been explained in terms of glow curve and kinetic parameters. The synthesized phosphors are expected to be promising candidates for applications as solid state lighting and optical displays. • Li 2 Zr(PO 4) 2 :Eu3+ phosphors are synthesized by solid state reaction (SSR) method at high temperature. • Structural behavior thoroughly discussed by XRD, SEM, EDX and FT-IR spectroscopy. • Photoluminescence, thermo luminescence and colorimetric Properties of phosphors have been investigated. • The Judd–Ofelt parameters of Li 2 Zr(PO 4) 2 :Eu3+ phosphors have also been calculated. • The transition probability, branching ratio, radiative lifetime, gain parameter and emission cross-section are also investigated. [ABSTRACT FROM AUTHOR]

A new series of optically translucent borosilicate glasses activated with varying concentrations of Dy3+ ions were fabricated by employing melt quenching method. Spectral investigations were conducted by recording the absorption, photoluminescent (PL) excitation and PL emission for Dy3+ activated borosilicate glasses. The absorption spectral information was exposed to Judd-Ofelt (J-O) analysis to calculate various radiative properties such as transition probability, total transition probability, branching ratios and radiative lifetimes of the as synthesized glasses. The excitation spectrum recorded under 483 nm emission wavelength possess a sharp peak at 348 nm in 0.1 mol% of Dy3+ ions doped borosilicate glass. Emission spectra recorded for all the Dy3+ ions activated borosilicate glasses under 348 nm intense excitation wavelength exhibit two potential peaks in visible region at 483 nm (4F 9/2 → 6H 15/2) and 575 nm (4F 9/2 → 6H 13/2). The emission centered at 483 nm is most prominent. Radiative properties measured from the absorption spectral feature were correlated with emission spectral information to estimate emission cross-section, gain bandwidth and optical gain parameters to understand the utility of the as synthesized glasses as photonic devices. The CIE coordinates measured for all the titled glasses are in good proximity with the white light coordinates of CIE 1931 diagram. • LPZABS glasses with Dy3+ ions were prepared by using melt quench technique. • XRD recorded for all the as prepared glasses confirm the glassy nature. • The bonding nature between Dy3+ ions and the surrounding ligands is ionic in nature. • Energy transfer through dipole-dipole interaction leads to concentration quenching. • CIE of 1.5mol% of Dy in LPZABS glasses are in proximity with CIE of white light. [ABSTRACT FROM AUTHOR]

A series of ZnF 2 -WO 2 -B 2 O 3 -TeO 2 (ZWFBT) glasses doped with different concentration of Dy3+ ions were prepared by using the melt quench method. The non-crystalline behavior of as-quenched ZWFBTDy glasses was approved by XRD spectra. The presence of different functional groups were identified by monitoring FT-IR spectra of ZWFBTDy glasses. The Differential Scanning Calorimetry (DSC) was used to estimate glass transition temperature (Tg) and thermal stability (ΔT) of an un-doped glass along with doped glasses. Physical parameters were estimated for Dy3+ doped ZWFBT glasses by using the formula available in the literature. The energy band gaps of as-quenched ZWFBTDy glasses were estimated by using three different theoretical models such as Mott and Davis relation, Hydrogenic Excitonic Model (HEM), and Urbach analysis. The optical absorption spectra were used to estimate the bonding parameters (δ) for elucidating the kind of bonding amide Dy3+ ions and its nearby ligands in the as-quenched glasses. The obtained experimental data from optical absorption spectra were compared with theoretical data calculated in the ambit of the Judd-Ofelt (J-O) theory. The J-O intensity parameters were estimated and a similar trend was observed (Ω 2 > Ω 6 > Ω 4 ) for the as-prepared ZWFBTDy glasses. The results obtained using J-O intensity parameters are found consistent with the bonding parameters. The radiative parameters such as branching ratio, radiative transition, radiative lifetime, total radiative transition, absorption, and emission cross-sections were evaluated and discussed. The gain coefficient was evaluated for the NIR transitions of as-quenched ZWFBTDy glasses. The obtained results suggested that the as-prepared ZWFBTDy glasses were auspicious candidates for laser emission and optical communication applications. [ABSTRACT FROM AUTHOR]

Fluoro phosphate glasses with different contents of barium and bismuth (8, 11, 14, 17 and 20 mol %) doped with Nd3+ were prepared by melt quenching technique. Importance of these modifier ions on structural transformation were carried out using XRD, FTIR, FT-Raman and 31P MAS NMR characterizations. 31P MAS NMR spectra revealed that structural modifications due to Bi 2 O 3 are more when compared with BaF 2 in this fluoro phosphate glass matrix. Three phenomenological Judd-Ofelt (J-O) parameters Ω λ (λ = 2, 4, 6) have been derived from the absorption spectra of Nd3+ doped barium and bismuth fluoro phosphate glasses. From the Judd-Ofelt parameters, transition probabilities (A), branching ratios (β) of certain transitions and radiative lifetimes of certain excited states of Nd3+ are extracted and reported. From the emission spectra, emission cross sections (σ e), band gains (σ e xΔλ eff) and optical gain parameters (σ e xτ R) were reckoned for the observed emission bands in these phosphate glasses. It is observed that barium glass resulted higher laser spectroscopic parameters (σ e , σ e xΔλ eff , σ e xτ R) which are crucial characteristics for exploring promising laser applications. Impact of Ba2+ and Bi3+ on luminescent properties of Nd3+ doped fluoro phosphate glasses has been examined in search of solid sate gain medium for laser emitting NIR light around 1.058 μm for photonic applications. •Nd3+ doped barium and bismuth flouro phosphate glasses are prepared by melt quenching technique. •Structural analysis for present fabricated vitreous material with the help of FT-Raman, FTIR and 31P NMR spectra. •Addition of Alkaline earth fluoride BaF 2 enhance the spectroscopic properties. •The Nd3+ doped Barium flouro phosphate glasses could be promising host in the NIR region around 1.058 μm. [ABSTRACT FROM AUTHOR]

We report the luminescence and energy transfer features in (B 2 O 3) 0.55-x (Li 2 O) 0.30 (MgO) 0.10 (Gd 2 O 3) 0.05 (Sm 2 O 3) x glasses, prepared via melt-quenching rout. By employing the Judd–Ofelt (JO) theory, the spectral parameters such as oscillator strengths, stimulated emission cross-sections, radiative transition probability and branching ratios are evaluated from the absorption and emission spectra. The dipole-dipole interaction as a dominant interaction mechanism is confirmed from Inokuti–Hirayama (IH) model. The luminescent color falls in the orange part of commission International de I'Eclaiage (CIE). The ultra-violet (UV) sensitization of visible emission of Sm3+ is analyzed by the photoluminescence (PL) emission spectra and the lifetime measurement. The Gd: 6P 7/2 –8S 7/2 emission in UV range and the Sm3+:4G 5/2 –6H J luminescence at 598 nm were observed upon the excitation of Gd:4f level by λ exc = 275 nm. Moreover, the impact of energy transfer on the donor-acceptor luminescence, quantum efficiency, and donor luminescence decay kinetics are investigated. It is found that efficient orange luminescence originates from Sm3+ emitting centers. These findings show that these as-prepared luminescent glasses are promising in orange LEDs and laser applications. Schematic excitation, emission (a) and ETC mechanism (b) in the energy level diagram of Gd3+ and Sm3+ in the LMgGBSm samples. Image 1 • ➢Prepared borate glasses co-doped with Gd3+ and Sm3+ via melt quenching technique. • ➢PL excitation and emission spectra showed concentration quenching at 0.3 mol% Sm 2 O 3. • ➢Enhanced Sm3+ and diminished Gd3+ luminescence confirmed energy transfer from Gd3+ to Sm3+. • ➢The energy transfer nature verified from lifetime's decay of Inokuti–Hirayama (IH) model. • ➢95% quantum efficiency was found in LMgGBSm0.3 sample for its 4G 5/2 level of Sm3+ ions. [ABSTRACT FROM AUTHOR]

Alkaline-Earth Boro Tellurite (AEBT) glasses (AEBT) activated with trivalent neodymium (Nd3+) ions were made by employing conventional melt quenching technique to explore their structural details, optical and photoluminescence (PL) properties. Energy Dispersive X-ray spectroscopy (EDX), absorption, fluorescence and fluorescence decay were performed to identify their feasibility for photonic applications. Judd-Ofelt (J-O) studies used for the absorption spectral features reveals larger values for Ω 2 and high radiative transition rates in AEBT glasses. The emission spectra of different concentrations of Nd3+ ions doped AEBT (AEBT: Nd3+) glasses show three transitions 4F 3/2 → 4I 9/2 , 4F 3/2 → 4I 11/2 and 4F 3/2 → 4I 13/2 at the wavelengths 887 nm, 1064 nm, and 1334 nm respectively. Among the observed transitions, 4F 3/2 → 4I 11/2 is the intense one observed in near - infrared (NIR) and is useful for lasing action at 1064 nm. The optical absorption, fluorescence and decay spectral studies, reveals that one mol% of Nd3+ ions concentration is quite suitable in AEBT glasses (AEBTNd1.0) to generate lasing action at 1064 nm suitable for NIR photonic broadband amplification applications. • EDX studies of AEBTNd1.0 glass revealed the chemical composition of the titled glasses. • The Judd-Ofelt analysis exposed the covalent nature of the Nd–O bond and low symmetry around Nd3+ ions in the glass network. • The transition 4F 3/2 → 4I 11/2 at 1064 nm has the highest stimulated emission cross-section values, branching ratios values for the AEBT glass doped with 1.0 mol% of Nd3+ ions. [ABSTRACT FROM AUTHOR]

Tm3+- doped GdScO 3 single crystal was successfully grown by the edge-defined film-fed method (EFG) for the first time. The spectroscopic properties of the crystal were investigated at room temperature. The absorption cross section of Tm:GdScO 3 at 795 nm is 1.58 × 10−20 cm2. By applying the Judd–Ofelt approach, the intensity parameters Ω 2,4,6 , radiative transition rates, branching ratios and radiative lifetime were calculated. Tm:GdScO 3 exhibits strong emission at 1460 nm and 2300 nm with stimulated emission cross section of 1.8 × 10−21 cm2 and 2.7 × 10−21 cm2, respectively. The fluorescence lifetime of the 3H 4 level was measured to be 265 μs. All the results indicated that the Tm:GdScO 3 crystal is a potential laser material. • Tm:GdScO 3 crystal was successfully grown by the edge-defined film-fed method (EFG) for the first time. • The structure parameters of Tm:GdScO 3 crystal were investigated by XRD. • Spectral parameters and Judd-Ofelt parameters of Tm:GdScO 3 crystal were obtained and compared. [ABSTRACT FROM AUTHOR]

Highlights: [•] Theory of the radiative characteristics of the doped nanocrystals in nanocomposite. [•] Decay rates of optical centers in magnetodielectric nanocomposite. [•] The analytical expressions for the electric-dipole and magnetic-dipole decay rates. [ABSTRACT FROM AUTHOR]

Optical absorption, excitation and emission spectra of trivalent europium (Eu3+) ions in Bi 2 ZnOB 2 O 6 nonlinear single crystal obtained by the Kyropoulos method were investigated. Strong, orange-red emissions of Eu3+ centered at 592 and 615 nm originate mainly from the 5D 0 →7F 1 and 7F 2 transitions, respectively. Judd-Ofelt intensity parameters for f-f transitions were derived from the room temperature (300 K) emission spectra and were used to calculate the radiative transition rates (A R), lifetimes (τ R) and branching ratios β for 5D 0 excited state of Eu3+. The calculated values of τ R and β were compared with the measured values for 5D 0 level. The 5D 0 fluorescence decay in 0.5 %Eu3+:Bi 2 ZnOB 2 O 6 was exponential with time constant of 1.1 ms at room temperature. The stimulated emission cross-sections σ were also evaluated for the 5D 0 → 7F J transitions for the first time in this system. We also report on laser site selective spectroscopy of a Eu3+: Bi 2 ZnOB 2 O 6 confirming the Eu3+ distribution into two sites. The site assignments of Eu3+ ions were discussed on the base of both optical spectroscopy results and structural analysis. • Spectroscopic properties of Eu3+: Bi 2 ZnOB 2 O 6 investigation. • Judd-Ofelt formalism applied to calculate Omega parameters. • Site assignments of Eu3+ ions in Bi 2 ZnOB 2 O 6 discussed. [ABSTRACT FROM AUTHOR]

The trivalent Europium (Eu3+) ions with varied concentrations doped in sodium-based fluoroborosilicate glasses were prepared via the melt quenching method. The prepared glasses were subjected to study their structural, optical, and fluorescence properties. The bonding and J-O intensity parameters (Ω 2 , Ω 4) were calculated from the obtained absorption spectrum and emission spectra, respectively. Two phonon sidebands were observed in the vibronic excitation spectrum. Among all prepared glasses, the prepared glass doped by 1.5 mol% Eu3+ ions exhibits the maximum emission intensity. For the all prepared glasses, intensity of electric dipole transition (5D 0 → 7F 2) has been varied with proportionate to concentration of trivalent Eu ions. Radiative parameters like bandwidth (Δλ eff), radiative transition probability, experimental and calculated branching ratios and stimulated emission cross-section were calculated. Eu3+ ions excited state (5D 0 level) lifetime was calculated using fluorescence decay analysis for varying concentrations of Eu3+ ions in prepared fluoroborosilicate glasses. The results obtained reveal that the investigated fluoroborosilicate glasses could be used for the design and development of red laser (612 nm) and display device applications. • Sodium based fluoroborosilicate glasses doped with Eu3+ ions prepared. • J-O parameters evaluated from emission spectra. • SBNCEu15 glass has high intensity at 612 nm for 394 nm excitation. • SBNCEu15 glass could be a potential candidate for visible solid-state lasers/photonic displays. [ABSTRACT FROM AUTHOR]

Trivalent neodymium (Nd3+) -doped Zn-Al-Ba borate glasses of composition (60-x)B 2 O 3 +20BaO+10Al 2 O 3 +10ZnO + xNd 2 O 3 (x = 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 mol%) were prepared by a conventional melt-quenching technique and studied their physical, structural, optical and luminescence properties. The amorphous nature of the glasses has been confirmed by X-ray diffraction patterns. The EDAX data shows percent mass of elements of the glass system. FTIR spectra confirm the formation of BO 3 and BO 4 groups in the glass structure and compared them with Raman spectra. The Judd-Ofelt theory was adopted to analyze the radiative properties of Nd 2 O 3 –doped glasses to derive oscillator strengths (f), JO parameters (Ω λ=2,4,6), stimulated emission cross-sections (σ e), radiative transition probabilities (A R), and branching ratios (β R) of various transitions of Nd3+ ions. The lifetime of the 4F 3/2 level of Nd3+ ions in the glasses decreases with the increase of Nd 2 O 3 concentration due to the shortened distance between Nd3+ ion in the glass structure. The strongest emission intensity is found at 1056 nm (4F 3/2 → 4I 11/2 transition) when excited by 808 nm. The optimum concentration of Nd 2 O 3 in the studied glasses is found to be 1.0 mol% based on luminescence intensity. All these results were compared with reported research of Nd3+:glasses to determine the lasing potentiality of studied glasses. • Nd3+-doped Zn-Al-Ba borate glasses have been prepared. • Direct (3.39–3.44 eV) and indirect (3.15–3.30 eV) optical band gaps have been evaluated for these glasses. • The strongest NIR emission due to 4F 3/2. → 4I 11/2 transition of Nd3+ ions has been observed at 1056 nm with β exp of 68% and σ e of 3.74 × 10−20 cm2 for BBaAZNd0.5 glass • The developed glasses could be potential candidates for infrared emitting device application. [ABSTRACT FROM AUTHOR]

The Ge 20 Ga 5 Sb 10 S 65 glasses doped with Er3+ ions (0; 0.1; 0.5; 1.0 mol. %) are investigated with optical, fluorescence and positron annihilation lifetime (PAL) spectroscopies. The optical and fluorescence measurements were performed at room (T R) and liquid nitrogen (T LN) temperatures. Transitions of Er3+ ions from the 4I 15/2 ground energy level to their higher levels 4F 9/2 , 4I 9/2 , 4I 11/2 and 4I 13/2 are well observed at both temperatures as absorption peaks at ~660, 810, 985 and 1540 nm, respectively. At T LN temperature, it is also possible to resolve the absorption band at ~550 nm, which corresponds to 4I 15/2 →4S 3/2 transition. The most intense fluorescence emission is observed at ~1 μm and ~1.5 μm wavelengths, which are identified as 4I 11/2 →4I 15/2 and 4I 13/2 →4I 15/2 radiative transitions of Er3+ ions. It is shown by PAL spectroscopy, that the addition of Er causes an increase of positron lifetime in defects τ 2 and a decrease in the intensity I 2 of the corresponded lifetime component. These changes are explained in terms of positron trapping reduction due to the occupation of positron trapping Ga-based sites in the glass matrix by Er3+ ions. • Four absorption bands of Er3+ are observed in the 0.5–2.5 μm region. • Cooling to LN temperature allows observing the absorption band at ~550 nm. • PAL results suggest Er3+ occupation of voids in the vicinity of Ga by forming Er3+-S-Ga bridges. • Emission of Er3+ at ~1180 nm under ~660 nm excitation appears at LN temperature. [ABSTRACT FROM AUTHOR]

Multi-component phosphate glasses with various Nd 2 O 3 content have been prepared using conventional melt-quenching technique. X-ray diffraction was carried out to study the structure of the prepared samples and it was found that all the obtained samples are amorphous. Electrostatic F (2) , F (4) , F (6) , and spin–orbit parameters have been determined from the absorption spectra. Judd-Ofelt theory has been used to analyze and evaluate the radiative transition probability, branching ratio, and radiative lifetime for the metastable level 4 F 3/2. Luminescence spectra and experimental lifetimes give information regarding the absence of chemical clustering and suggest that the physical clustering is negligible making the glass a suitable candidate for photonic applications. Image 1 [ABSTRACT FROM AUTHOR]