The synthesis and fluorescent properties of nanoparticulate ZrO2 doped with Eu using continuous hydrothermal synthesis

Abstract

Fluorescent nanoparticles of zirconia doped with europium (ZrO 2 :Eu 3+ ) have been produced via the co-precipitation of simple metal salt precursors using continuous supercritical water hydrothermal synthesis. The effect of reaction temperature and residence time on both particle size and conversion were investigated. Increasing the reaction temperature from 200 to 400 • C increases the size of the particles: smaller diameters (<5 nm) were produced at lower temperatures and larger diameters (>20 nm) at higher temperatures. Varying residence time at constant temperatures (between 3.7 and 7 seconds) did not significantly affect the particle size. The structure of the nanoparticles synthesised at 400 • C was revealed to be cubic by X-ray diffraction. Conversion of the metal precursors to ZrO 2 :Eu 3+ was improved from 4 to 99% on increasing the temperature between 250 and 350 • C. The photoluminescent properties of the nanoparticles were also explored with respect to synthesis temperature. Fluorescence upon UV excitation at 255 nm, originating from Eu 3+ doped in ZrO 2 , was not significantly affected by the synthesis temperature. The emission spectra demonstrated characteristic f → f transitions of Eu 3+ ions and can be explained through an effective dispersion of these ions within the ZrO 2 nanoparticles. Initial cell toxicity studies suggest that ZrO 2 :Eu 3+ nanoparticles do not cause any significant increase in cell death in Chinese hamster ovary cells following an 18 hour incubation at 37 • C. This paper describes a 'green' and controlled method for the continuous production of research scale quantities of nanomaterials.

Photoluminescent ZrO2:Eu3+ Nanofibers Prepared via Electrospinning

“…The emission spectra had several bands in the red region of the visible spectrum corresponding to the transition 5 D 0 ! 7 F J (J ¼ 1; 2; 3; 4), 6,[15][16][17] and the two most intense emission bands were observed at wavelength 606 and 591 nm, which belong to the transitions 5 D 0 ! 7 F 2 (an electric dipole transition) and 5 D 0 !…”

“…[6][7][8][9] Recently, the properties of ZrO 2 doped with Sm 3þ , Tm 3þ , Er 3þ , Ce 3þ , Pr 3þ , and Eu 3þ ions have been investigated. 6,[10][11][12][13][14][15][16][17] The ZrO 2 :Eu 3þ combination is of particular interest as a photoluminescent material, and several groups have examined the relationship between the photoluminescent properties of the europium centers and structural modifications to zirconia nanoparticles upon doping. 6,[15][16][17] To apply photoluminescent nanomaterials in existing and future technologies, it is necessary to optimize not only the chemical structure of the dopant-host combination (chemical optimization), but also to optimize the morphology of the produced materials (physical optimization).…”

“…Prior research efforts with ZrO 2 :Eu 3þ have dealt with nanoparticles. 6,[15][16][17] Frequently, one-dimensional (1D) nanostructured materials are desirable, such as nanofibers, nanowires, nanorods and nanotubes. 18,19) The combination of a high surface area, flexibility, and superior directionality of 1D nanomaterials makes them suitable for many applications, such as membranes, catalyst supports, sensors, and electrodes.…”

Rapid Production of Micro- and Nano-particles Using Supercritical Water

“…Adding of 10% Y concentration was sufficient for the predominant formation of the tetragonal modification of ZrO 2 . Fluorescent nanoparticles of zirconia doped with europium (ZrO 2 : Eu 3+ ) have been produced via the co-precipitation of simple metal salt precursors using continuous SCW hydrothermal synthesis [57]. Particles with small diameters (< 5 nm) at low temperatures but large diameters (> 20 nm) at high temperatures were produced from 473 to 673 K. Nanocrystalline BaZrO 3 was synthesized in SCW in a continuous way using barium precursors of Ba(CH 3 COO) 2 and Ba(NO 3 ) 2 that led to the pure perovskite phase [58].…”

Phase composition and photoluminescence correlations in nanocrystalline ZrO2:Eu3+ phosphors synthesized under hydrothermal conditions

“…It is critical from a fundamental point of view to identify correlations between the zirconia crystalline structure and the europium luminescence properties in the ZrO 2 :Eu 3+ nanoparticles, and also the nature of their changes as a function of temperature and dopant concentration. Also, the combination of the physico-chemical properties of ZrO 2 matrix acting as an oscillator with the europium optical characteristics gives a considerable potential in the field of photonic applications, such as solid-state lasers, sensors, optical amplifiers, scintillators, phosphors and lamps [36].…”