Gd2O3-modulated borate glass for the enhancement of near-infrared emission via energy transfer from Gd3+ to Nd3.

(Li2O)0.20(SrO)0.30(Nd2O3)0.01(B2O3)0.49-x(Gd2O3)x, where x = 0, 3, 5, 7, and 10 mol%, glass was melt-quenched to test it as a laser source in the near-infrared (NIR) region. The structural modification, absorption spectra, Judd-Ofelt (J-O) parameters, luminescence spectra, radiative laser parameters, lifetimes, XRD, and FTIR spectra were studied. Luminescence spectra excited at λexc = 584 nm revealed the highest intensity peak at 1073 nm due to the transition of 4F3/2 → 4I11/2. An important phenomenon of concentration quenching was observed and optimized luminescence was achieved with the sample having the concentration x = 07 mol%. The lifetimes of the donor and acceptor and energy transfer from gadolinium to neodymium were obtained from the luminescence decay kinetics. The findings show that Nd-doped Gd2O3-modified glass materials have potential as NIR laser sources.

Luminescence properties and energy transfer of Nd3+- Er3+/ Nd3+-Pr3+ co-doped LFP glasses system.

The motivation for this research is that the emission spectra using directly pumped laser diodes have not yet been found. We want to explore the luminescence properties of a co-doped laser material utilizing a diode laser as an optical pump. The research method used standard melt-quench and was stimulated by a laser diode (808 and 980 nm). The double doped of Nd3+- Er3+/Nd3+-Pr3+ ions with glasses system of lithium-fluorophosphate (LFP) had a strong band emission at 1056 nm, which transitioned at 4F3/2 â†’ 4I11/2 and showed a drop in intensity from co-doping with Er3+ and Pr3+ ions. The fluorescence width at half maximum (FWHM) of the glasses is calculated to identify whether the sample may be used as a laser application. The FWHM values are found to be 22-28 nm. Decay time values were shown to decrease with increasing concentrations of Er3+ and Pr3+ ions and were used for energy transfer calculations. The Quantum Yields (QYs), efficiency in the transfer of energy and the possibility transfer energy were measured and calculated that confirm the possibility of energy transfer from Nd3+ to Er3+ and Pr3+ ions. Since, the emission spectrum at 1535 nm was found, this is a good reason for it to be used as an optical device.

Hazardous radiation protective glasses for medical and research laboratories.

In the current study, the bismuth oxide (Bi2O3) content was inter-substituted with gadolinium oxide (Gd2O3) in sodium borate glass. Glass sample density and molar volume values show a reverse trend. The optical transparent radiation shielding glasses are more commonly used materials in hospitals or any hazardous radiation working environments, the glasses used in this work are more emphasized on their superior transmittance and acceptable for shielding materials for commercial purposes. The optical band gap value was calculated using the Tauc plot and absorption fitting method. Radiation shielding parameters like mass attenuation co-efficient, effective atomic number, effective electron density, equivalent atomic number, lead equivalent thickness, half value layer, tenth value layer, Geometric-Progression fitting parameters like (b, c, a, XK, and d), γ-ray build-up factor, and exposure build-up factor have all been evaluated. In the current work, photoluminescence studies for Gd3+ ions were investigated and discussed.

Red emission material from Eu3+ ion doped in oxy-fluoroborate glass system.

The aim of the work is to prepare (51-x)B2O3 + 23CaF2 + 10Li2O + 10Na2O + 6BaO + xEu2O3 glasses with various concentration, analyse the optical/radiative properties and compare with other reported literature. In this work, the Judd-Ofelt analysis was employed to evaluate oscillator strength, JO parameters. Using JO parameters, radiative properties of the prepared samples were evaluated to understand their branching ratios, stimulated emission cross-section and radiative lifetime. The phonon coupling constant was evaluated using phonon sideband and compared with other literatures. The present glasses doped with Eu3+ ions find a potential use in orange red light emitting optical display device applications.

The influence of CeF3 on radiation hardness and luminescence properties of Gd2O3-B2O3 glass scintillator.

The effect of CeF3 concentration and γ-irradiation on the physical, optical and luminescence properties of Gd2O3-B2O3-CeF3 glasses were studied in this work. Before irradiation, the addition of CeF3 in glass degraded the network connectivity observed from FTIR and possibly created the non-bridging oxygen (NBO) in glass structure. This NBO caused the reduction of Ce3+/Ce4+ ratio in XANES, the red-shift in transmission spectra and the raise of refractive index with addition of CeF3 content. Such red-shift also was influenced by 4f-5d transition of Ce3+ dopant. This ion generated the strongest photoluminescence (PL) and radioluminescence (RL) in 0.3 mol% CeF3-doped glass with nanoseconds decay time. The irradiation with γ-rays damaged the glass structure, broke the chemical bonds, and created color center in the glass network. The non-bridging oxygen hole center (NBOHC), that absorbed photons in the visible light region, caused the darkening, color change and increment of refractive index. These irradiation effects on glass were mitigated by the addition of CeF3 that the electron donation of Ce3+ decreased the number of NBOHC. The Ce3+/Ce4+ ratio in most glasses after irradiation then reduced compared to them before irradiation, resulting to the decrease in PL and RL intensity. Our results confirm that CeF3 can enhance the radiation hardness of glass and the 0.3 mol% CeF3-doped glass is a promising glass scintillator.

Luminescence characteristics of Sm3+-doped lithium barium gadolinium silicate glasses for Orange LED's.

Traditional melt-quenching technique is adopted for synthesis of Sm2O3 doped lithium barium gadolinium silicate (LBGS: Li2O-BaO-Gd2O3-SiO2) glasses. These glass samples are characterized by different spectroscopic techniques under ambient conditions. Density and molar volume of the present LBGS glass samples increase with increasing Sm3+ ion-concentration. JO intensity parameters Ωλ (where λ = 2, 4 and 6) are evaluated by using Judd-Ofelt theory and Ω4 > Ω2 > Ω6 trend is observed. Furthermore, these parameters are used to evaluate radiative properties like radiative transition probability, branching ratio, radiative lifetime and stimulated emission cross-section for state 4G5/2 of Sm3+ ion. The measured color coordinates for the title glass fall within orange region of CIE diagram. For the present LBGS glasses, the correlated color temperature values are less than warm. The lifetime for the 4G5/2 decreases from 2.468 to 0.566 ms when concentration increases from 0.1 to 2.0 mol% of Sm3+ ions. The analysis of non-exponential behavior of the decay profile through Inokuti-Hirayama model for S = 6 indicates that the energy transfer between Sm3+ ions is due to dipole-dipole interactions. Further energy transfer parameters (Q), critical distance (Ro, Å) and donor-acceptor interaction parameters (CDA x 10-40 cm6/s) of Sm3+ ions doped LBGS glasses were evaluated and compared to other glasses. From the evaluated results it is suggested that the present novelty of the work emphasizes on new matrix LBGS doped with Sm3+ ions showing increasing energy transfer rate with increasing in concentration of Sm2O3 content indicating these glasses are potential candidate for orange-light emitting device applications.

Energy transfer phenomenon of Gd3+ to excited ground state of Eu3+ ions in Li2O-BaO-Gd2O3-SiO2-Eu2O3 glasses.

Li2O-BaO-Gd2O3-SiO2 glasses with different concentration of Eu3+ ions were developed by the traditional melt quenching technique and characterized via FTIR, absorption, excitation, emission and CIE color coordinates analysis for visible red emission application. The FTIR shows strong band at position 740 cm-1 which is attributed to Si-O-Si symmetric stretching mode. Density and molar volume of LBGSEu glasses increases with Eu3+ ions concentration. The covalent nature of bond between the Eu3+ ions and surrounding ligands was confirmed from the bonding parameter (δ). From absorption spectra JO-parameters and oscillator strength are evaluated for LBGSEu6 glass. From JO-parameters, Eu3+ ions have asymmetric coordination environment and stronger covalency. The phonon line PSB (22,522 cm-1) confirm the phonon energy ≈971 cm-1, that corresponds to the energy of one phonon associated with maximum energy of the vibrational mode couple to Eu3+ ions. Under 275 nm and 393 nm excitation, intense red emission was observed at 613 nm, we observe efficient energy transfer phenomena from Gd3+ → Eu3+ in these glasses. Increasing trend of IR with increasing concentration of Eu2O3 indicates the asymmetric environment around Eu3+ ions in LBGS. Moreover, from JO analysis, LBGS glasses have high capability for red laser device with high lasing power and energy extraction ratio. The fluorescence lifetimes show decreasing trend in lifetime with increasing concentration of Eu2O3 is due to radiative transition. From CIE color coordinate, the CIE color coordinates of LBGSEu6 glass fall in reddish region close to orange region and can be useful for optical display devices.

Crystal growth and scintillation properties of YAG:Ce3+ for γ and α detection.

A bulk single crystal of yttrium aluminum garnet (Y3Al5O12:Ce3+, YAG:Ce3+) with good optical quality and free of cracks has been grown successfully by the Kyropoulos method. The dimension of the as grown crystal boule was Ø 20 × 30 cm3. The cut and polished crystal sample of dimensions 1 × 1 × 0.5 cm3 was used for further measurements. The phase purity was confirmed by powder X-ray diffraction pattern analysis. The scintillation properties, such as X-ray emission spectrum, pulse height spectra, energy resolution, and scintillation decay time, were investigated using a 137Cs γ-ray source. The recorded X-ray emission spectrum shows a broad band between 500 and 700 nm with a peak at around 540 nm, which is attributed to the 5d-4f transition of the Ce3+ ion. The pulse-shape discrimination (PSD) of α and γ signals in a YAG:Ce3+ crystal has been studied by using different pulse shapes. The grown YAG:Ce3+ crystal which is non-hygroscopic, chemically inert, fast inorganic scintillator could be used for radiation detection application in nuclear, and high energy physics.

Non-proportionality study of CaMoO4 and GAGG:Ce scintillation crystals using Compton coincidence technique.

In this study, the CCT technique and nuclear instrument module (NIM) setup for the measurements of coincidence electron energy spectra of calcium molybdate (CaMoO4) and cerium doped gadolinium aluminium gallium garnet (Gd3Al2Ga3O12:Ce or GAGG:Ce) scintillation crystals were carried out. The (137)Cs irradiated gamma rays with an energy (Eγ) of 662keV was used as a radioactive source. The coincidence electron energy spectra were recorded at seven scattering angles of 30°-120°. It was found that seven corresponding electron energies were in the range of 100.5-435.4keV. The results show that, for all electron energies, the electron energy peaks of CaMoO4 crystal yielded higher number of counts than those of GAGG:Ce crystal. The electron energy resolution, the light yield and non-proportionality were also determined. It was found that the energy resolutions are inverse proportional to the square root of electron energy for both crystals. Furthermore, the results show that the light yield of GAGG:Ce crystal is much higher than that of CaMoO4 crystal. It was also found that both CaMoO4 and GAGG:Ce crystals demonstrated good proportional property in the electron energy range of 260-435.4keV.

Nonproportionality of electron response using CCT: plastic scintillator.

The scintillation response of a plastic scintillator (NE102) has been characterized using compton coincidence technique. The coincidence technique allowed detection of nearly monoenergetic internal electrons resulting from the scattering of incident 662keV gamma-rays within a primary NE102 detector. Scattered gamma-rays were detected using a secondary NaI(Tl) detector in a coincidence mode. The electron response nonproportionality of NE102 plastic scintillator was measured using this technique for electron energies ranging from 28 to 436keV, by varying the scattering angle. The NE102 showed a good proportionality of light yield within 3% at energies between 90 and 436keV. Below 90keV, the light yield decreases by about 20% upon lowering the electron energy to 28keV. The electron energy resolution of NE102 was also measured using this technique in the energy range from 68 to 436keV. It has been found that the energy resolution varies from 25.2% at 68keV to 11.8% at 436keV.