Aerosol route in Processing of Nanostructured Functional Materials

Abstract

Moreover, the solution routes and low temperature processing minimize the potential for contamination, which is very important for the most applications in the electronic, optoelectronic, chemical industries etc. that are sensitive to some of the impurities.

Aerosol route as a feasible bottom-up chemical approach for up-converting phosphor particles processing

“…Among other yttrium compounds, yttrium oxide represents an efficient UCP phosphor host material for the substitution of rare earth ions because of its low phonon energy, <600 cm À1 , broad optical transparency range 0.2-8 lm, high refractive index, >1.9 and large energy band-gap, 5.8 eV [6]. Yttrium oxide posses a cubic crystal structure with a space group, S.G. Ia3-(T 7 h ) in which there are two crystallographically different rare-earth sites, C2 (75%) and S6 (25%); by that, a unit cell is composed of four atom positions, three having a point symmetry C2 and one position with a point symmetry S6 [7]. ters in the host matrix and the overall particle structure and morphology control, which altogether signify the importance of innovative and controllable UCP phosphor processing route in the current research efforts [7][8][9].…”

“…Yttrium oxide posses a cubic crystal structure with a space group, S.G. Ia3-(T 7 h ) in which there are two crystallographically different rare-earth sites, C2 (75%) and S6 (25%); by that, a unit cell is composed of four atom positions, three having a point symmetry C2 and one position with a point symmetry S6 [7]. ters in the host matrix and the overall particle structure and morphology control, which altogether signify the importance of innovative and controllable UCP phosphor processing route in the current research efforts [7][8][9]. Moreover, of particular impor-tance is the controlled synthesis of the host lattice having targeting crystal structure which determines the distance between the dop-ant ions, their relative spatial position, their coordination numbers, and the type of anions surrounding the dopant.…”

“…During the process, aerosol droplets undergo evaporation, drying and solute precipitation in a single-step, enabling spherical, either hollow or dense, agglomerate-free, submicronic ''secondary'' particles to be obtained exhibiting the composite inner nanostructure and representing an assembly of primary nanoparticles. The size and size distribution of secondary particles are mainly influenced by the properties of precursor solutions and aerosol generation, while the size of primary particles depends on the timetemperature history of particle formation and materials properties [7]. There is a diversity of aerosol routes, depending mainly on the manner of aerosol formation and how the aerosol decomposition energy is transferred to the precursor system, reflecting on the most important particle formation parameters: residence time and temperature distribution [7].…”

“…The size and size distribution of secondary particles are mainly influenced by the properties of precursor solutions and aerosol generation, while the size of primary particles depends on the timetemperature history of particle formation and materials properties [7]. There is a diversity of aerosol routes, depending mainly on the manner of aerosol formation and how the aerosol decomposition energy is transferred to the precursor system, reflecting on the most important particle formation parameters: residence time and temperature distribution [7]. Among them, flame synthesis represents a straightforward large-scale aerosol route for producing spherical nanoparticles in different oxide and non-oxide systems, enabling higher temperatures and shorter residence time to be obtained.…”

“…It has been reported a successful processing of nanocrystalline up conversion phosphor particles in Yb (Tm, Er) doped-sodium yttrium fluoride and Sm-doped Gd 2 O 3 by this route [13,15]. For the case of hot-wall flow reactor, a well-controlled temperature profile over long residence times can be achieved, however the direct processing of nanoscaled particles is limited and associated either with the precursor solution dilution or urea/salt assisted solution modification [7], which in turn influence on the powder production rates.…”