Bright White Upconversion Emission from Tm3+/Yb3+/Er3+-Doped Lu3Ga5O12 Nanocrystals

Mahalingam, Venkataramanan; Mangiarini, Francesca; Vetrone, Fiorenzo; Venkatramu, V.; Bettinelli, Marco; Speghini, Adolfo; Capobianco, John A.

doi:10.1021/jp8076479

Cited by 148 publications

(74 citation statements)

References 26 publications

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“…Using the deep s state of oxygen as the common reference, we calculated the relative position of band edges of various Lu 3 B 5 O 12 compounds, where B=(Al, Ga, In, As, and Sb). Other garnets are less common than Al garnets, with only Lu 3 Ga 5 O 12 [37][38][39] and Lu 3 Sb 5 O 12 [40] reported in literature. However, analyzing how other B cations impact the electronic structure may guide future doping and admixing strategies where full substitution may not be required.…”

Section: A Al Substitutionmentioning

confidence: 99%

Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles

Yadav¹,

Uberuaga²,

Nikl³

et al. 2015

Phys. Rev. Applied

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Complex doping schemes in RE3Al5O12 (RE=rare earth element) garnet compounds have recently led to pronounced improvements in scintillator performance. Specifically, by admixing lutetium and yttrium aluminate garnets with gallium and gadolinium, the band-gap was altered in a manner that facilitated the removal of deleterious electron trapping associated with cation antisite defects. Here, we expand upon this initial work to systematically investigate the effect of substitutional admixing on the energy levels of band edges. Density functional theory was used to survey potential admixing candidates that modify either the conduction band minimum (CBM) or valence band maximum (VBM). We considered two sets of compositions based on Lu3B5O12 where B = Al, Ga, In, As, and Sb; and RE3Al5O12, where RE = Lu, Gd, Dy, and Er. We found that admixing with various RE cations does not appreciably effect the band gap or band edges. In contrast, substituting Al with cations of dissimilar ionic radii has a profound impact on the band structure. We further show that certain dopants can be used to selectively modify only the CBM or the VBM. Specifically, Ga and In decrease the band gap by lowering the CBM, while As and Sb decrease the band gap by raising the VBM. These results demonstrate a powerful approach to quickly screen the impact of dopants on the electronic structure of scintillator compounds, identifying those dopants which alter the band edges in very specific ways to eliminate both electron and hole traps responsible for performance limitations. This approach should be broadly applicable for the optimization of electronic and optical performance for a wide range of compounds by tuning the VBM and CBM.

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Section: A Al Substitutionmentioning

confidence: 99%

Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles

Yadav¹,

Uberuaga²,

Nikl³

et al. 2015

Phys. Rev. Applied

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“…Thus there is an increasing demand for upconversion materials with important applications in upconversion lasers, due to the availability of powerful near-infrared commercial laser diodes, IR detection by conversion to visible light, where detectors are more efficient, and biological fluorescence labels and imaging or 3-D displays. 1,2,[11][12][13][14][15][16] When the RE 3+ ions are incorporated into the nanocrystals their upconversion efficiencies depend on the …”

mentioning

confidence: 99%

Synthesis, structure and luminescence of Er3+-doped Y3Ga5O12 nano-garnets

et al. 2012

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A novel Y 3(1Àx) Er 3x Ga 5 O 12 nanocrystalline garnet has been synthesized by a sol-gel technique and a complete structural, morphological, vibrational, and optical characterization has been carried out in order to correlate the local structure of the Er 3+ ions with their optical properties. The synthesized nanocrystals are found in a single-phase garnet structure with an average grain size of around 60 nm. The good crystalline quality of the garnet structure is confirmed by FTIR and Raman measurements, since the phonon modes of the nano-garnet are similar to those found in the single crystal garnet. Under blue laser excitation, intense green and red visible and 1.5 mm infrared luminescences are observed, whose relative intensities are very sensitive to the Er 3+ concentration. The dynamics of these emissions under pulsed laser excitations are analyzed in the framework of different energy transfer interactions. Intense visible upconverted luminescence can be clearly observed by the naked eye for all synthesized Er 3+ -doped Y 3 Ga 5 O 12 nano-garnets under a cw 790 nm laser excitation. The power dependency and the dynamics of the upconverted luminescence confirm the existence of different two-photon upconversion processes for the green and red emissions that strongly depend on the Er 3+ concentration, showing the potential of these nano-garnets as excellent candidates for developing new optical devices. A IntroductionNowadays, rare earth (RE 3+ )-doped nanocrystals attract great attention due to their size, shape, and phase-dependent structural and luminescence properties, which make them suitable for fundamental and technological applications.1,2 On the other hand, the favorable physical and chemical properties of the oxide garnet crystals, such as high transparency from the UV to the mid-IR, high thermal conductivity, hardness, good chemical stability, and relatively low-energy phonons, make them one of the most important families of host matrices for the RE 3+ ions with interesting luminescence properties already used in lasers and phosphors. ions without charge compensation. 8,9From the point of view of the potential optical applications of the RE 3+ ions, one of the most interesting phenomena is their capacity to convert the infrared absorbed radiation into visible emitting light, known as energy upconversion.10 The particular selection of one or various RE 3+ ions and their concentrations allows controlling the upconverted visible luminescence to match a specific coordinate of colour, or even the generation of white light as a combination of red, green and blue (RGB) emissions. Thus there is an increasing demand for upconversion materials with important applications in upconversion lasers, due to the availability of powerful near-infrared commercial laser diodes, IR detection by conversion to visible light, where detectors are more efficient, and biological fluorescence labels and imaging or 3-D displays. 1,2,[11][12][13][14][15][16] When the RE 3+ ions are incorporated into the nanocrystals their upcon...

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“…16 When the concentrations of REI such as Yb 3+ as the sensitizer ion and Er 3+ , Tm 3+ , Ho 3+ and/or Pr 3+ as activator ions are appropriately adjusted in these nanocrystals, efficient multicolor and white light emission through red-green-blue (RGB) combination can be achieved usually by simple excitation with a commercial 980 nm laser diode. 15,[17][18][19] Owing to their high potential as an alternative source for lighting, laser or sensing, great interest has thus emerged in investigating beyond the extensively studied REI doped glassy materials [20][21][22][23] by embedding their REI into up-converter nanocrystals and forming more efficient active glass-ceramics. [24][25][26] The main part of the vitreous materials explored with a view to prepare these luminescent glass-ceramics is based on oxyuoride mixed glass systems such as uoro-germanate [27][28][29] or uoro-alumino-silicate.…”

Section: -7mentioning

confidence: 99%

“…15,[17][18][19] The involved mechanisms will be described later in the text. The concentration of TmF 3 in the glass of nominal composition (NaPO 3 ) 40 -(YF 3 ) 30 -(BaF 2 ) 20 -(CaF 2 ) 10 (mol%) was varied from 1 to 4 wt% while the concentrations of YbF 3 and ErF 3 were maintained constant at 4 wt% and 2 wt%, respectively.…”

Section: +mentioning

confidence: 99%

White light and multicolor emission tuning in triply doped Yb³⁺/Tm³⁺/Er³⁺ novel fluoro-phosphate transparent glass-ceramics

et al. 2014

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, Er 3+ and Tm 3+ doped fluoro-phosphate glasses belonging to the system NaPO 3 -YF 3 -BaF 2 -CaF 2 and containing up to 10 wt% of rare-earth ion fluorides were prepared and characterized by differential scanning calorimetry, absorption spectroscopy and up-conversion emission spectroscopy under excitation with a 975 nm laser diode. Transparent and homogeneous glass-ceramics have been reproducibly obtained with a view to manage the red, green and blue emission bands and generate white light. X-ray diffraction as well as electron microscopy techniques have confirmed the formation of fluorite-type cubic nanocrystals at the beginning of the crystallization process while complex nanocrystalline phases are formed after a longer heat-treatment. The prepared glass-ceramics exhibit high optical transparency even after 170 h of thermal treatment. An improvement of up-conversion emission intensity -from 10 to 160 times larger -was measured in the glass-ceramics when compared to the parent glass, suggesting an important incorporation of the rare-earth ions into the crystalline phase(s). The involved mechanisms and lifetime were described in detail as a function of heat-treatment time. Finally, a large range of designable color rendering (from orange to turquoise through white) can be observed in these materials by controlling the laser excitation power and the crystallization rate.

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Bright White Upconversion Emission from Tm³⁺/Yb³⁺/Er³⁺-Doped Lu₃Ga₅O₁₂ Nanocrystals

Cited by 148 publications

References 26 publications

Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles

Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles

Synthesis, structure and luminescence of Er3+-doped Y3Ga5O12 nano-garnets

White light and multicolor emission tuning in triply doped Yb³⁺/Tm³⁺/Er³⁺ novel fluoro-phosphate transparent glass-ceramics

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Bright White Upconversion Emission from Tm3+/Yb3+/Er3+-Doped Lu3Ga5O12 Nanocrystals

Cited by 148 publications

References 26 publications

Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles

Band-Gap and Band-Edge Engineering of Multicomponent Garnet Scintillators from First Principles

Synthesis, structure and luminescence of Er3+-doped Y3Ga5O12 nano-garnets

White light and multicolor emission tuning in triply doped Yb3+/Tm3+/Er3+ novel fluoro-phosphate transparent glass-ceramics

Contact Info

Product

Resources

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Bright White Upconversion Emission from Tm³⁺/Yb³⁺/Er³⁺-Doped Lu₃Ga₅O₁₂ Nanocrystals

White light and multicolor emission tuning in triply doped Yb³⁺/Tm³⁺/Er³⁺ novel fluoro-phosphate transparent glass-ceramics