Doped Zinc Phosphate Glasses Research Articles

Novel synthesis and spectroscopic analysis of gallium oxide doped zinc phosphate glass

Phosphate glasses are known for their wide applications in the field of optical fiber, lasers, seals and sensors. Glass system containing (40-x) ZnO-xGa2O3-50P2O5- Na2O, where x=0 to 10mol % were prepared. The effect of gallium oxide on the properties of these glasses were studied. To observe the structure of prepared phosphate glasses FTIR was used under the wavelength range of 400-4000 cm-1 . The prominent peaks appeared in region 400 cm-1 to 2500 cm-1 . The glasses were transparent up to 1500 cm-1 which make them suitable in the field of lasers. The FTIR also confirmed that Q2 structure dominates these glasses

A DFT-based model to the interpretation of DC conductivity in transition metals doped zinc phosphate glass

Ternary zinc–sodium–phosphate glasses doped with transition metal of the composition Na2MxZn1−xP2O7(x = 0, 1, 2 and 5 mol %) (where M = Ni, Cu and Co) were prepared by the traditional quenching method. The ac conductivity measurements at different temperatures for the prepared glasses have been investigated, and the activation energy for dc conduction has been determined in each transition metal doped sample. The results showed that the evolution of the activation energy of the conductivity depends on the nature of the dopant ions. A model based on formal density functional theory concept in which the electrical charge exchanged between the transition-metal cations and the surrounding material surface is proposed. The outcome is a “simplified” formula which allows us to explain the evolution of the ionic dc conductivity activation energy as a function of the doped ion in interaction with the cation and the surface.

Physical and optical analysis of Sm3+ doped zinc phosphate glass

Sm3+ (0.1, 0.2, 0.3, 0.4 & 0.5 wt%) doped zinc phosphate glasses have been prepared by melt quenching technique. Their physical, as well as optical properties, have been studied. The UV–Vis absorption spectroscopy was carried on in the wavelength range of 400–700 nm which reveals five absorption bands at 406 nm, 445 nm, 478 nm, 533 nm, and 572 nm respectively. The direct bandgap is found to be 2.42–2.47 eV while the indirect bandgap is 2.30–2.34 eV. Urbach energy is calculated to be 0.4237–0.4445 eV. The other parameters like dielectric susceptibility, metallization, refractive index, oxygen packing density, etc., have also been studied.

Tunable white light emission through energy transfer processes between silver species in Ag-doped zinc phosphate glass

Silver doped zinc phosphate glass was successfully synthesized at different molar concentrations of AgCl from 1% up to 20%. Zinc phosphate glass shows a high capacity to hold silver impurities without loss of optical quality. This material shows two different centers able to emit blue and green-red light, the first one from isolated Ag+ ions and the latter from Ag+ pairs. The intensity of each emission can be tuned by varying the composition of silver in the matrix, reaching the white light emission at 12 and 14% molar AgCl. Two energy transfer mechanisms were detected: charge transfer from zinc phosphate glass matrix to isolated Ag+ ions (that can improve the forbidden blue emission) and energy transfer from Ag+ single ions to Ag+ pairs.

Cold bluish white and blue emissions in Cu+-doped zinc phosphate glasses

Reducing agent-free zinc phosphate glasses doped with cooper ions (Cu+) were synthesized by melt-quenching technique. The physical properties of these glasses such as density, molar volume and refractive index were studied. The X-ray diffraction (XRD) patterns for all prepared glasses, confirm their amorphous structure. Raman spectroscopy suggest that the phosphate network is composed by tetrahedral PO4 units, since the vibrations of P–O–P, PO2 and PO, observed in the spectra, belong to the PO4 units. All glasses display absorptions bands in the ultraviolet and near infrared regions, associated with the absorption edge and contribution of the Cu+:1Ag → 1T2g + 3T2g (280 nm) and Cu2+: 2Eg → 2Tg (890 nm) transitions, respectively. The optical band gap values determined from the absorption spectra assuming indirect optical band gap, are reduced from 4.83 to 2.95 eV for Cu+ content in the range of 0–0.3 mol%. For Cu+ concentration higher than 0.3 mol%, band gap values increase up to 3.17 eV. Such last behaviour was attributed to the reduction of the amount of Cu+ species and/or Moss-Burstein effect. The emission spectra of the Cu+-doped zinc phosphate glasses upon 272 and 290 nm excitation, displayed overall bluish white light and blue emission, depending the excitation wavelength and Cu+ contents. A maximum photoluminescence quantum yield value of 12.5% with an inherent uncertainty up to 3.75%, was reached under 290 nm excitation. The emission decay time profiles were well fitted to a bi-exponential function from which the average lifetimes values resulted to be in the interval of 26.8–16.7 μs, which are shortened for Cu+ contents higher than 0.3 mol%. The structural and photoluminescence characteristic makes of the reducing agent-free Cu+-doped zinc phosphate glasses potentially attractive for blue phosphors and WLEDs applications.

Judd-Ofelt Parameters of Erbium Doped Zinc Phosphate Glass Containing Natural Ferrite Oxide Nanoparticles

Erbium ions (Er3+) doped zinc phosphate glass system with varying contents of natural ferrite (Fe3O4) nanoparticles were prepared using melt quenching method. The glass is characterized by x-ray diffraction (XRD) and UV-VIS NIR spectrometer. It is observed that the amorphous nature of the glass is confirmed by x-ray diffraction. The absorption spectra of the glass are recorded in the UV-Visible in the range of 400-1600 nm. The UV-VIS NIR spectra reveal ten absorption peaks centered at 376, 406, 420, 486, 522, 546, 652, 798, 976 and 1534 nm, correspond to the transitions from the ground state 4I15/2 to higher 4I13/2, 4I11/2, 4I9/2, 4F9/2, 4S3/2, 2H11/2, 4F7/2, 4F3/2, 2H9/2, 4G11/2 levels, respectively. Effects of natural ferrite oxide nanoparticles on the absorption and emission properties of the synthesized glasses were analyzed via Judd-Ofelt (J-O) theory. The J-O intensity-parameters (W2, W4, W6) analysis demonstrate a significant increase of spectroscopic quality factors.Keywords: Fe3O4 NPs, Absorption, Judd-Ofelt.

Spectroscopic investigations of near-infrared emission from Nd3+-doped zinc-phosphate glasses: Judd-Ofelt evaluation

Zinc-phosphate glasses doped with different concentrations of Nd3+ ions have been prepared by the melt quenching technique and characterized the spectroscopic properties. The physical properties by means of density and molar volume are determined. The amorphous nature of the glasses has been confirmed by X–ray diffraction analysis. FTIR spectra exhibited the fundamental stretching vibrations modes of glass network. In order to study the spectroscopic properties of fabricated glasses, absorption and emission spectroscopy has been performed. Additionally, the spectroscopic properties of Nd3+ ions were analyzed using J–O theory. UV–Vis–NIR absorption spectra of glass samples divulged twelve significant peaks. Considerable enhancement of Ω2 values with increasing neodymium content indicated an improvement in the covalency and asymmetry of Nd3+ ions environment. Under the excitation of 808 nm laser diode, two near-infrared emission bands at around 890 and 1060 nm from 4F3/2 → 4I9/2 and 4I11/2 radiative transitions respectively were observed in the Nd3+ single doped glasses. The major intensity is observed for 1060 nm for such glass samples. Nd3+ ions dopant is found to augment the luminescence intensity by a factor as much as 2.23 times as the concentration of Nd3+ ions increase up to 1.5 mol%. The lifetimes of this level has been experimentally determined through decay profile studies. The developed glass possesses high fluorescence quantum efficiency (η = 96%). The results indicate that the prepared glass system could be a suitable candidate for using it as laser gain media around 1060 nm, solid-state lasers and fiber amplifiers.

Zinc phosphate glasses activated with Dy3+/Eu3+/Sm3+ and Tb3+/Eu3+/Sm3+ for reddish-orange and yellowish white phosphor applications

Spectroscopic evaluations of Dy3+/Eu3+/Sm3+ and Tb3+/Eu3+/Sm3+ doped zinc phosphate glasses, based on excitation and emission spectra, and emission decay measurements, are particularly focused on potential white light-emitting diodes applications. All the excitation wavelengths located in the 337–382 nm range, match with the emissions of AlGaN, GaN and InGaN LEDs. The Dy3+/Eu3+/Sm3+ doped zinc phosphate glass excited at 347 nm displays yellowish white tonality according with the x = 0.396 and y = 0.408 CIE1931 chromaticity coordinates and correlated color temperature (CCT) value of 3837 K, whereas under 362, 374 and 382 nm excitations, it displays reddish-orange tonality with CIE1931 chromaticity coordinates (and CCT values): x = 0.503 and y = 0.398 (2075 K), x = 0.570 and y = 0.388 (1640 K), and x = 0.527 and y = 0.386 (1804 K), respectively, with color purities higher than 72%. The Dy3+ and Sm3+ emission decay analysis suggests that non-radiative energy transfer processes from Dy3+ to Eu3+ and/or Sm3+ and Sm3+ to Eu3+ take place with efficiencies of 0.09 ± 0.04 and 0.15 ± 0.04, respectively. The Dy3+ and Sm3+ emission decay fitting by the Inokuti-Hirayama model, indicates that electric dipole-quadrupole and quadrupole-quadrupole interactions might respectively mediate the energy transfer processes inside the Dy3+-Sm3+-Eu3+ clusters. The Tb3+/Eu3+/Sm3+ doped zinc phosphate glasses only exhibits reddish-orange emission tonality with CIE1931 chromaticity coordinates and (CCT values): x = 0.510 and y = 0.425 (2210 K), x = 0.549 and y = 0.399 (1754 K), x = 0.510 and y = 0.411 (2108 K), and x = 0.544 and y = 0.385 (1710 K), under 337, 361, 374 and 380 nm excitations, respectively, with color purities higher than 79% in all cases. The Tb3+ and Sm3+ emission decay shortening in presence of Sm3+ and Eu3+, and Tb3+ and Eu3+, respectively, points out Tb3+→ Eu3+ and/or Sm3+ and Sm3+ → Eu3+ non-radiative energy transfers, with efficiencies of 0.08 ± 0.04 and 0.04 ± 0.05, respectively. The Inokuti-Hirayama model suggests that the Tb3+→ Eu3+ and/or Sm3+ and Sm3+ → Eu3+ energy transfer processes might be, respectively, dominated by electric dipole-quadrupole and quadrupole-quadrupole interactions inside Tb3+-Sm3+-Eu3+ clusters.

Comprehensive study on compositional modification of Tb3+ doped zinc phosphate glass

Series of glass composition (60-x) P2O5 -40 ZnO –(x) Tb2O3 where x = 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mol % are prepared by conventional melt quenching technique. X-Ray Diffraction (XRD), FTIR, UV-Vis-NIR and the photoluminescence (PL) spectroscopy are used to characterize the physical, structural and optical behavior of the glass sample. The XRD pattern confirms the amorphous nature and DTA verified the thermal stability of all the glass samples. Glass with 1.5 mol % of Tb2O3 possesses the highest thermal stability. Glass density is found to increase proportionally with increasing amount of Tb3+ while the molar volume behaves reversely. Six main IR absorption bands centered at about 540, 748, 891, 1085 and 1294 cm− 1 are evidenced. The UV-Vis NIR absorption spectra reveals the absorption center band at about 540, 376, 488 and 1920 nm corresponding to the absorption from 7F6 ground state to various excited state of Tb3+ ion. The optical band gaps for direct and indirect transition are in the range 4.53–5.07 eV and 4.30 eV-4.56 eV respectively. The Urbach energy decreases with the increasing concentration of Tb2O3. The PL emission spectra reveals several prominent peaks at 413, 435, 457, 488, 540, 585 and 620 nm due to electronic transition from 5D3→7F5, 5D3→7F4, 5D3→7F3, 5D4→7F6, 5D4→7F5, 5D4→7F3 and 5D4→7F5 respectively.

Yttrium-europium oxide doped zinc phosphate glasses, a luminescence study

The luminescent and structural properties of Zn3(PO2)4:Y2O3/Eu3+ glasses synthesized by melting method at a temperature of 1000°C are described; the doping was performed with Y2O3:Eu3+ powders which were synthesized by the simple evaporation method at 1100°C with a concentration of 4.3% Eu3+ as determined by EDS. These glasses have a transparency above 90% within the range 400–700nm, they present an intense luminescence that is associated with characteristic intra-electronic energy levels of Eu3+ ion transitions. The dominant emission peak is at 613nm, corresponding to the 5D0 to 7F2 transition and the dominant excitation peak is at λexc=395nm. The XRD results indicate that they remain amorphous even when they are doped with different masses of the powders Y2O3:Eu3+; the CIE diagram shows that the luminescence of these glasses Zn3(PO2)4:Y2O3/Eu3+ and Y2O3:Eu3+ powders lies in the red region.

Intense orange emission in Pr3+ and NIR emission at 1.53 μm in Er3+ doped zinc phosphate glasses for potential broadband optical amplifier

Praseodymium (Pr3+) and Erbium (Er3+) doped zinc phosphate glasses with chemical compositions (60 − x) NH4H2PO4 + 20ZnO + 10BaF2 + 10NaF + xRE (where RE = Pr6O11 and Er2O3, x = 0.1, 0.5, 1.0, 1.5 and 2.0 mol%) have been prepared by melt quenching technique. Amorphous structure was ascertained by XRD analysis. The functional and vibrational bands have been assigned and clearly elucidated by FT-IR and Raman spectral profiles for all the glass samples. Judd–Ofelt (J–O) intensity parameters (Ω λ : λ = 2, 4, 6) have been obtained from the spectral intensities of different absorption bands of Pr3+ and Er3+ ions through optical absorption spectra. The radiative properties such as radiative transition probabilities (A R ), radiative lifetimes (τ R ) and branching ratios (β R ) for different excited states were calculated by using J–O intensity parameters. Visible photoluminescence spectra have exhibited six emission bands (3P1 → 3H5, 1D2 → 3H4, 3P0 → 3F2, 3P1 → 3F3, 3P0 → 3F3 and 3P0 → 3F4 states) for all the concentrations of Pr3+ ions. NIR photoluminescence spectra exhibited one emission band (4I15/2 → 4I13/2) of Er3+ ions. The energy transfer mechanism that leads to the quenching of lifetimes of 1D2 and 4I13/2 states have been discussed at higher concentrations of Pr3+ and Er3+ ions, respectively. These glasses were suggested as suitable hosts to produce intense orange emission at 608 nm for Pr3+ ion and efficient lasing action in NIR region at 1534 nm for Er3+ ion.

RGB emission of Mn2 + doped zinc phosphate glass

We report the photoluminescence (PL) of Mn2+ doped zinc phosphate glass as melted. Raman, X-Ray diffraction (XRD), Energy-Dispersive X-ray Spectroscopy (EDS) were used to get a better characterization. During the synthesis process, the Mn2+ ions, tetrahedrally coordinated (IVMn2+) in the glass, partially precipitate on octahedral sites (VIMn2+) that gives place to the simultaneous occurrence of green and red luminescence, due to the spin-forbidden 4T1(G)→6A1(S) and 4T1g(G)→6A1g(S) transitions in IVMn2+ and VIMn2+ respectively. The ratio IVMn2+/VIMn2+ can be controlled by the increase of %Mn in the glass and, hence, the ratio between green and red emissions can be controlled. The change of Mn2+ ions coordination form 4 to 6 is seen by Electron Paramagnetic Resonance (EPR) and lifetime measurements. PL results indicate the precipitation of crystalline ZnO phases with relatively small particle size that produces its characteristic blue emission due to conduction band to valence band exciton transitions. The transition 6A1(S)→4E(D) of Mn2+ centered at 350nm can produce a blue and red dual luminescence by the overlap with the valence band to conduction band transition of ZnO, while the transition 6A1(S)→4A1(G) of Mn2+ centered at 409nm produces the green and red dual luminescence that is dependent on %Mn in the glass.

X-ray induced luminescence of Sn2+-centers in zinc phosphate glasses

Photo- and X-ray induced luminescence properties of Sn2+-doped zinc phosphate glasses with different chemical compositions were investigated. Decay constants of the glasses decrease with increasing the ZnO amount, which are independent of excitation light sources. By comparison of emission properties, we have found that the glass structure affects both luminescence properties. The broader emission band in the P2O5-rich glasses suggests that the site variation of Sn2+ centers is mainly due to the P2O5 sub-networks. It is expected that the P2O5 sub-networks are effective for not only photoluminescence but also the X-ray induced radio-luminescence and storage luminescence.

Investigations on Eu3+ Doped Zinc Phosphate Glasses for Photonic Applications

Investigations on Eu3+ Doped Zinc Phosphate Glasses for Photonic Applications

Photoluminescence and spectral performance of manganese ions in zinc phosphate and barium phosphate host glasses

Zinc and barium metaphosphate glasses containing dopants of MnO2 (2, 4, 8%) were prepared. Collective studies were carried out through optical, photoluminescence and Fourier transform infrared (FTIR) spectral measurements for the prepared glasses before and after gamma irradiation. Electron spin resonance (ESR), thermal expansion and crystallization studies were also investigated. Optical spectra for undoped and MnO2–glasses reveal strong ultraviolet (UV) absorption due to trace iron impurity in the materials used for preparation of glasses and Mn2+ ions are not identified due to spin–forbidden nature of their spectra. Upon gamma irradiation, the MnO2–doped glasses reveal extension of the UV absorption exhibiting two peaks together with the generation of an induced broad visible band centered at 570–580nm. Extra two glasses doped with 8% MnO2 were melted under reducing condition and they showed characteristic band at 410nm related to Mn2+ ions absorption. Photoluminescence (PL) spectra reveal two excitation peaks in MnO2–doped zinc phosphate glasses at 348 and a sharp peak at 410nm while the MnO2–doped barium phosphate glasses exhibit a sharp peak at 410nm and a curvature at 348nm. The emission spectra show a broad band centered at 620nm in both glasses but with a curvature at 605–610nm in zinc phosphate glasses which are correlated with the transition 4T1g→6A1g.The efficiency of the photoluminescence increases with the MnO2 content and the heat treatment. The values of the optical band gap (Eopt) and Urbach energy (∆E) were calculated. FTIR spectra reveal vibrational bands due to phosphate network mainly of metaphosphate groups but in zinc phosphate glasses, the mid spectra show compact network because of the ability of Zn2+ ions to participate partly as ZnO4 or P–O–Zn linkages. Thermal expansion data show different responses. Zinc phosphate glasses show anomalous behavior related to the change in the coordination of zinc cations while barium phosphate glasses exhibit normal expansion because Ba2+ ions exist only as modifiers. The crystallization behavior reflects also anomalous behavior. The zinc phosphate glass crystallizes in two crystalline species, mainly zinc metaphosphate phase and another zinc phosphate (3ZnO·P2O5) phase while the barium phosphate glass crystallizes only in barium metaphosphate phase.

Green to white tunable light emitting phosphors: Dy3+/Tb3+ in zinc phosphate glasses

Dy3+/Tb3+-doped zinc phosphate glasses of composition in mol.%: 98.0Zn(PO3)2–2.0Dy2O3, (100.0−x)Zn(PO3)2–xTb2O3 and (98.0−x)Zn(PO3)2–2.0Dy2O3–xTb2O3, x = 0.6, 1.0, 2.0 and 5.0, were prepared by conventional melt quenching technique, and characterized by photoluminescence and decay time spectroscopy. The emission color can be adjusted from neutral white of 4279 K (98.0 Zn(PO3)2-2.0 Dy2O3 glass) toward the green region by codoping with Tb3+ from 0.6 to 5.0 mol% of Tb2O3 upon Dy3+ excitation at 392 nm. The Tb3+ emissions (5D4 → 7F6,5,4,3) being sensitized by Dy3+ through a non-radiative energy transfer. Dysprosium 4F9/2 level emissions can also be sensitized through excitation of Tb3+ at 284 nm with an efficiency up to of 80%. Additionally, upon 284 nm excitation dominant 5D4 → 7F5 green emission in detriment of the 5D3 → 7FJ blue one is promoted by a cross relaxation process between Tb3+ and Dy3+ in addition to that among Tb3+ ions. In consequence, the most intense green emission observed in the ZP2Dy5Tb phosphor gives rise to a color purity of 67.8% and chromaticity coordinates (0.29, 0.59) very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. Such cross relaxation processes enhancing the green emission of Tb3+ with ultraviolet excitation might contribute to increment the spectral response of solar photovoltaic cells by down-shifting of the incident solar spectrum.

Concentration‐dependent studies of Nd3+‐doped zinc phosphate glasses for NIR photoluminescence at 1.05 μm

Nd3+ -doped lead-free zinc phosphate glasses with the chemical compositions (60-x) NH4 H2 PO4 +20ZnO+10BaF2 +10NaF+xNd2 O3 (where x=0.5, 1.0, 1.5, 2.0 and 2.5mol%) were prepared using a melt quenching technique. Vibrational bands were assigned and clearly elucidated by Raman spectral profiles for all the glass samples. Judd-Ofelt (J-O) intensity parameters (Ωλ : λ=2, 4, 6) were obtained from the spectral intensities of different absorption bands of Nd3+ ions. Radiative properties such as radiative transition probabilities (AR ), radiative lifetimes (τR ) and branching ratios (βR ) for different excited states were calculated using J-O parameters. The near infrared (NIR) photoluminescence spectra exhibited three emission bands (4 F3/2 level to 4 I13/2 , 4 I11/2 and 4 I9/2 states) for all the concentrations of Nd3+ ions. Various luminescence properties were studied by varying the Nd3+ concentration for the three spectral profiles. Fluorescence decay curves of the 4 F3/2 level were recorded. The energy transfer mechanism that leads to quenching of the 4 F3/2 state lifetimes was discussed at higher concentration of Nd3+ ions. These glasses are suggested as suitable hosts to produce efficient lasing action in NIR region at 1.05μm.

Luminescence performance of Eu3+-doped lead-free zinc phosphate glasses for red emission

In this study, the luminescence performance of zinc phosphate glasses containing Eu3+ ion with the chemical compositions (60–x)NH4H2PO4-20ZnO-10BaF2-10NaF–x Eu2O3 (where x = 0.2, 0.5, 1.0 and 1.5 mol%) has been studied. These glasses were characterized by several spectroscopic techniques at room temperature. All the glasses showed relatively broad fluorescence excitation and luminescence spectra. Luminescence spectra of these glasses exhibit characteristic emission of Eu3+ ion with an intense and most prominent red emission (614 nm), which is attributed to 5D0 → 7F2 transition. Judd-Ofelt (Ω2, Ω4) parameters have been evaluated from the luminescence intensity ratios of 5D0 → 7FJ (where J = 2 and 4) to 5D0 → 7F1 transition. Using J-O parameters and excitation spectra, the radiative parameters are calculated for different Eu3+-doped glasses. Effect of γ-irradiation at fixed dose has been studied for all the Eu3+-doped glass matrices. The lifetimes of the excited level, 5D0, have been measured experimentally through decay profiles. The colour chromaticity coordinates are calculated and represented in the chromaticity diagram for Eu3+-doped zinc phosphate glasses for all concentrations.

Spectroscopic investigation on thermally stable Dy3+ doped zinc phosphate glasses for white light emitting diodes

Optically transparent dysprosium ions doped lead zinc phosphate glasses have been prepared via melt quenching technique to study the luminescent properties and their applications for white light emitting diodes (w-LEDs). X-ray diffraction (XRD) pattern confirmed the amorphous nature of the as-prepared glass. The glass transition temperature (Tg) and thermal stability (ΔT) were determined by using Differential Scanning Calorimetry (DSC). The vibrational features were characterized by Raman and FT-IR, which indicate the presence of poly-phosphate structure dominated by Q2 and Q1 structural units. The intense emission bands observed at 482 nm (blue) and 574 nm (yellow), where the yellow to blue intensity ratio for all excitation wavelengths (NUV to blue range) were found to lie in the vicinity of unity, yielding to intense white light emission. The evaluated CIE chromaticity coordinates (0.309, 0.341) for the optimized glass (GP10) at 350 nm excitation fall in the pure white region, which is in proximity with commercial w-LED (Blue LED + YAG:Ce3+) and NTSC system for white light emission. The correlated color temperature (CCT) of the optimized glass is 6547 K, which represents cool white light emission. The decay profiles have been measured for the excited 4F9/2 level and analyzed.

Luminescence properties of Tb3+-doped zinc phosphate glasses for green laser application

Tb3+-doped zinc phosphate glasses of composition in mol%: (100.0 − x)Zn(PO3)2 – xTb2O3, x = 0.6, 1.0, 2.0 and 5.0, were prepared by conventional melt quenching technique and characterized by photoluminescence and decay time spectroscopy. The integrated intensities of the 5D4 → 7F5 (green at 541 nm) and 5D3 → 7F4 (blue at 435 nm) emissions and their intensity ratios IG/IB upon 350 nm excitation have been evaluated as function of Tb3+ concentration. The CIE1931 color of the glasses excited at 350 nm varies from turquoise to green by increasing the Tb3+ content. The increased IG/IB ratio up to a factor of 364 for the phosphor with the highest Tb3+ content (ZP5Tb) is consistent with the observed shift toward the green region in the CIE coordinates, so that the ZP5Tb glass exhibits a green color purity of 66.9% with chromaticity coordinates (0.290, 0.581), being very close to those (0.29, 0.60) of European Broadcasting Union illuminant green. This interesting feature of the ZP5Tb phosphor, together with an experimental branching ratio larger than 60% of the 5D4 → 7F5 green emission, highlights its capability as solid state green laser pumped by AlGaN (350 nm) LEDs. The decay time profiles of the 5D3 level resulted to be non-exponential for all the studied concentrations due to energy transfer between Tb3+ ions through cross-relaxation. Such decay profiles were well fitted to the Inokuti–Hirayama model for S = 6, which indicates that an electric dipole-dipole interaction might be the dominant mechanism in the cross-relaxation energy transfer occurring in Tb3+ ion clusters.