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In this work, the visible luminescence of P 2 O 5 -KF-Al 2 O 3 glasses with Tm 2 O 3 was studied. The Tm3+ ion can have a strong blue emission, which allows the development of LEDs in this color region. This study refers to the synthesis of oxyfluorophosphate glasses, 38P 2 O 5 +(50-x)KF+12Al 2 O 3 +xTm 2 O 3 (PKAl:Tm), with x = 0.25, 0.50, 0.75, and 1.00 mol%, by the melt-quenching method. The prepared materials showed amorphous characteristics verified by XRD data. The absorption spectra shown six main bands characteristic of Tm3+ ions, from ground state 3H 6 to excited levels 3F 4 , 3H 4 , 3H 5 , 3F 3,2 , 1G 4 and 1D 2 , in which the intensities increased with the concentration of Tm 2 O 3. In the FTIR spectra, it was verified that the profiles of the PKAl samples are similar to glasses based on phosphate systems. The Judd-Ofelt parameters were calculated, where for PKAl glasses the trend was Ω 2 >Ω 4 >Ω 6. The excitation spectra of PKAl:Tm glasses shown an intense band centered at 358 nm (3H 6 →1D 2). The luminescence spectra with excitation at 358 nm shown two bands at 453 nm (1D 2 →3F 4), and 480 nm (1G 4 →3H 6); the highest emission intensity was observed to the sample doped with 0.75 mol% of Tm 2 O 3. The calculated CIE diagram shown that the doped samples have coordinates close to the primary blue color, which favors the application for the development of blue LEDs and wLEDs. The decay curves for the 1D 2 level were fitted by single exponential with lifetime values decreasing with increasing concentration of Tm 2 O 3. These results show that the PKAl:Tm glasses are potential candidates for applications in LEDs. [Display omitted] • 38P 2 O 5 -(50-x)KF-12Al 2 O 3 -xTm 2 O 3 glasses, x = 0.25, 0.50, 0.75, and 1.00 mol%. • The optical parameters, transition probability and radiative lifetimes were evaluated using the Judd-Ofelt theory. • CIE coordinates appeared in the deep blue regions under 357 excitation, with main emission at 454 nm. • Oxyflorophosphate glasses doped with Tm 2 O 3 are candidates for photonic applications in blue emitters. [ABSTRACT FROM AUTHOR]

Abstract: The spectroscopic properties of tellurite glasses of composition (in mol%) TNKNd: (70− x)TeO2–15Nb2O5–15K2O–xNd2O3 (x =0.1, 1.0, 1.5, 2.0 and 2.5) and TNLNd10: 69TeO2–15Nb2O5–15Li2O–1.0Nd2O3 and lithium metaborate glass of composition LBNNd10: 89LiBO2–10Nb2O5–1.0Nd2O3 have been investigated using absorption and emission spectra and decay curve analysis. An energy level analysis has been carried out considering the experimental energy positions of the absorption and emission bands, using the free-ion Hamiltonian model. The spectral intensities have been calculated by using the Judd–Ofelt theory and in turn the radiative properties such as radiative transition probabilities, emission cross-sections, branching ratios and radiative lifetimes have been estimated. The decay curves at the lower concentrations are exponential while they show a non-exponential behavior at higher concentrations (⩾1.0mol%) due to energy transfer processes. The effective lifetimes for the 4F3/2 level are found to decrease with increase in Nd2O3 concentration for all the glasses under investigation. The non-exponential decay curves have been well-fitted to the Yokota–Tanimoto model with S =6, indicating that the nature of energy transfer is of dipole–dipole type and energy migration also plays an important role. The results obtained have been compared with Nd3+-doped phosphate, fluorophosphate, lead borate, tellurite, germanate and silicate glasses and Nd3+-doped YAG ceramic and Ca2Nb2O7 crystals. [Copyright &y& Elsevier]

Abstract: This article reports the effect of mixed alkalis on the optical absorption and emission spectra of Sm3+ and Dy3+ doped chloroborate glass matrices of the compositions 69.5B2O3 xLiCl(30− x)NaCl0.5R2O3 and 69.5B2O3 xLiCl(30− x)KCl0.5R2O3 (where R=Sm and Dy and x =5, 10, 15, 20 and 25). Using Judd–Ofelt theory, the spectral intensities and Judd–Ofelt intensity parameters (Ω 2, Ω 4 and Ω 6) were obtained from the measured absorption bands of the spectra. Using these intensity parameters, total radiative transition probabilities (A T), radiative lifetimes (τ R), branching ratios (β) and peak emission cross-sections (σ P) were obtained for the two rare earth ions in these two glass matrices. Variation of these parameters with x in the glass matrix has been discussed. It is found that for Sm3+ ion, the transition, 4G5/2 → 6H9/2 shows highest emission cross-section and is maximum at x =10mol% in lithium–sodium and at x =20mol% in lithium–potassium glass matrices. For Dy3+ ion, the transition, 4F9/2 → 6H13/2 shows highest emission cross-section and is maximum at x =20mol% in lithium–sodium and at x =10mol% in lithium–potassium glass matrix. [Copyright &y& Elsevier]

Abstract: Structural and spectroscopic properties of neodymium doped sodium borate and fluoroborate glasses of composition (in mol%) (99− X) B2O3 + XNa2O+1Nd2O3, X =49.5, 39.5 and 29.5 and 49.5B2O3 + XNa2O+(49.5− X) NaF+1Nd2O3, X =0 and 24.75 have been investigated using XRD, FTIR, absorption and emission spectra and decay curve. The XRD of the glasses confirm their glassy nature and the FTIR spectra reveal the presence of BO3 and BO4 units along with the strong OH− groups in the glasses. The UV–vis-NIR absorption spectra were used to calculate the bonding parameters ( and δ), to identify the ionic/covalent nature of the glasses. The spectral intensities have been calculated by using Judd–Ofelt analysis and inturn used to estimate radiative properties such as radiative transition probabilities, radiative lifetimes, branching ratios, peak stimulated emission cross-sections. Branching ratios and stimulated emission cross-sections show that the 4F3/2 → 4I11/2 transition of the glasses under investigation has the strong emission around 1060nm. The decay from the 4F3/2 level of Nd3+ ions is found to be single exponential. Multiphonon relaxation and quenching due to OH− groups play a governing role in the luminescence quenching of 4F3/2 level of Nd3+ ions in the titled glasses. The results obtained are compared with reports on similar glasses. [Copyright &y& Elsevier]

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]