Large-scale production of spherical Y₂O₃:Eu³⁺ phosphor powders with narrow size distribution using a two-step spray drying method

Abstract

ARTICLE This journal isA simple strategy to prepare dense spherical Y 2 O 3 :Eu 3+ phosphor particles with a narrow size distribution is proposed, using two steps of spray drying carried out with a commercially available spray dryer. The key idea is first to prepare hollow Y 2 O 3 :Eu 3+ precursor particles by spray drying an aqueous precursor solution containing citric acid. Thereafter, nanosized particles are obtained from the precursor powders by simple ball milling and dispersed in water to form a colloidal suspension that is spray dried, forming porous granules of dense spherical nanoparticles. Next, highly crystalline Y 2 O 3 :Eu 3+ is obtained by sintering the granules at temperatures above 1200°C. The resulting Y 2 O 3 :Eu 3+ particles are spherical and are shown to have good luminescence properties as a red phosphor. The feasibility of the strategy proposed here is proved experimentally.

Hollow Nano- and Microstructures as Catalysts

“…Nevertheless, production rates of 30 g/h are reported, which substantially exceeds the amounts accessible by solution-based methods. However, for most of the protocols only the synthesis of hollow shells is described, − being the single-step encapsulation of nanoparticulate cargos more challenging in this case.…”

“…Spray drying operates at mild temperatures, typically below 200 °C, and therefore often merely serves to evaporate the solvent from the atomized feedstock. As a result, further thermal treatments are often required to develop more robust or crystalline products . However, spray-drying temperatures have been reported to be suitable to achieve the single-step synthesis of hollow capsules of organic materials, such as polymers, which exhibit limited thermal stability.…”