Effect of crystal nature on upconversion luminescence in Er3+:ZrO2 nanocrystals

Patra, Amitava; Friend, Christopher S.; Kapoor, R.; Prasad, Paras N.

doi:10.1063/1.1592891

Cited by 247 publications

(137 citation statements)

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“…[54, 56, 57, 64, 65, 71, 82, 84, 85, 87-92, 94-96, 98, 105, 127, 128, 167, 180, 181, 190, 197-199, 202, 205, 209, 219, 220, 256, 262, 278, 296-332] Dabei wurde eine Vielzahl von Materialklassen untersucht, darunter binäre [82,94,167,180,181,197,199,305] und ternäre Oxide, [85,198] Phosphate, [64] Vanadate, [84] Molybdate, [278] Titanate, [88] Zirconate, [314] Silicate, [56,312] Hydroxide [57,333] und Oxysulfide. [197,333,334] 2003 haben wir erstmals die Photonen-UC in transparenten Kolloiden beschrieben.…”

Section: Oxidnanokristalleunclassified

Nanopartikel für die Aufwärtskonversion

2011

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Mit Upconversion (UC, Aufwärtskonversion) werden nichtlineare optische Prozesse beschrieben, bei denen die aufeinander folgende Absorption von zwei oder mehr Photonen mit vergleichsweise großer Wellenlänge zur Emission von Strahlung mit kürzerer Wellenlänge (Emission vom anti‐Stokes‐Typ) führt. Im Unterschied zu anderen Emissionen auf Basis einer Mehrphotonenabsorption können UC‐Prozesse auch mit niedrigen Energiedichten effizient angeregt werden. Die effizientesten heute bekannten UC‐Prozesse werden in Seltenerd‐dotierten Festkörperverbindungen beobachtet. Die Forschungen auf dem Gebiet nanokristalliner Materialien führten schließlich zur Entwicklung von Synthesemethoden für kleine, hocheffiziente UC‐Partikel mit enger Partikelgrößenverteilung, die transparente Lösungen in einer Vielzahl von Lösungsmitteln bilden. Mittlerweile gibt es Syntheserouten für qualitativ hochwertige UC‐Nanokristalle, die eine Steuerung von kolloidaler Löslichkeit, Partikelgröße, Kristallstruktur, optischen Eigenschaften und Partikelform ermöglichen. Zurzeit werden diese Partikel als vielversprechende Alternative zu organischen Fluorophoren und Halbleiternanopartikeln (“Quantenpunkten”) in der medizinischen Bildgebung diskutiert.

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Section: Oxidnanokristalleunclassified

Nanopartikel für die Aufwärtskonversion

2011

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“…This kind of phase transformation aroused by the increased sintering temperature is consistent with the previous report. 7 In addition, phase compositions of Er 3+ :ZrO 2 NCs hardly change by introducing Li + under 600 and 1000 • C sintering. Interestingly, under 800 • C calcination, tetragonal is dominant in Er 3+ :ZrO 2 with composition of about 70%, while monoclinic is the main phase in Er 3+ /Li + :ZrO 2 with composition of about 94%.…”

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“…The symmetry of lattice for monoclinic is 2/m (C 2h ) and for tetragonal is 4/mmm (D 4h ). Therefore, monoclinic phase is less symmetric than tetragonal phase, 7 which means M-phase ZrO 2 benefits the UC-PL emission.…”

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confidence: 99%

“…[1][2][3][4] Compared with other RE ions doped oxide NCs, Er 3+ doped ZrO 2 arouses special interest. [5][6][7] Because Er 3+ provides plenty of energy levels with broad emission bands and intermediate levels ( 4 I 11/2 and 4 I 13/2 ) with long lifetimes, which are easily accessible with NIR radiation, and ZrO 2 has good transparency from visible to NIR, great chemical stability and low phonon energy (470 cm -1 ) which benefit UC-PL emission. 6 ZrO 2 , with a phase-dependent potential application in a number of technologies, has three polymorph forms including monoclinic, tetragonal, and cubic.…”

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“…9,10 It is well known that crystallite size is dependent on the calcined temperature, which increases with the increasing temperature. Thus ZrO 2 NCs calcined at lower temperature (800 • C) with relatively small sizes are usually tetragonal and diminishing with the increasing sintering temperature, and monoclinic is the dominant phase when temperature is 1000 • C. 7 To produce efficient UC-PL in RE ion doped ZrO 2 , higher sintering temperature is necessary because monoclinic appears at higher temperature with lower symmetry which benefit UC-PL. However, high temperature means high a electronic mail: liulu@hrbeu.edu.cn cost and more difficulty in the synthesized procedure.…”

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Enhanced upconversion fluorescence of Er3+:ZrO2 nanocrystals induced by phase transformation

et al. 2012

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In this letter, we demonstrate for the first time a growth of monoclinic phase ZrO2 nanocrytals based on a sol-gel method, compared to the ordinary sol-gel procedure, our method decreases the synthesized temperature from ∼1000 °C to ∼800 °C. In addition, it is found that Er3+ in monoclinic phase ZrO2 nanocrystals have greatly enhanced upconversion emissions under infrared LD excitation due to its lower environmental symmetry

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Nanocontrol of Excitation Dynamics

Prasad¹

2004

Nanophotonics

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Chapter 6 deals with the manipulation of a nanoscale dielectric environment to control excitation dynamics. Even though this may not have a quantum confinement effect on electronic states (such as in insulating materials), the dynamics of electronic excitation can still exhibit important manifestations derived from nanostructure control. The nanostructure dependence of dynamics can be derived from the interaction of the electronic excitation with the surroundings and its phonon modes.The factors that control the dynamics are discussed in Section 6.1. The use of dielectric modification to control excited-state dynamics and thus enhance a particular optical manifestation (such as emission at a specific wavelength) is illustrated by two examples:1. The rare-earth ion containing nanostructures in which the phonon interactions with the surrounding lattice and subsequently the excited-state relaxation is controlled to produce enhancement of a particular emission. An important type of emission is that of the Er 3+ ions at 1550 nm, which forms the basis for optical amplification. It is shown in Section 6.2 that the nanostructure control produces significant increase of the emission lifetime to provide improved optical amplification ability. Another important type of emission, discussed in Section 6.3, is up-conversion where excitation by a CW-IR laser beam at 974 nm produces up-converted emission in the red, green, or blue regions, depending on the nanostructure composition and interactions of the rare-earth ion containing nanoparticles. This up-conversion process finds important applications in up-conversion lasing (Scheps, 1996). Another application is in display technology (Downing et al., 1996). Other applications are for infrared quantum counters and temperature sensors (Joubert, 1999). The up-conversion process also finds biological applications in bioimaging and light-activated therapy, which are discussed in Chapter 13. Another important type of up-conversion process is photon avalanche that occurs above a certain pump threshold power. It is discussed in Section 6.4. Section 6.5 describes the converse process of down-conversion, also called quantum cutting.2. Organic-inorganic hybrid core-shell nanoparticles where an organic fluorescent molecule is encapsulated within an inorganic shell (silica shell in the present case). This example is presented in Section 6.6. The shell shields the organic molecule from interactions with the external environments (such as aqueous environments) which act as a quencher of emission. The enhanced emission efficiency, to-

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Effect of crystal nature on upconversion luminescence in Er3+:ZrO2 nanocrystals

Cited by 247 publications

References 12 publications

Nanopartikel für die Aufwärtskonversion

Nanopartikel für die Aufwärtskonversion

Enhanced upconversion fluorescence of Er3+:ZrO2 nanocrystals induced by phase transformation

Nanocontrol of Excitation Dynamics

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