Deep insight into the photoluminescent monocrystalline particles: Heat-treatment, structure, mechanisms and mechanics

The red light emitting down-converting Ag@Y2O3:Eu3+ phosphor particles were synthesized by one-step ultrasonic spray pyrolysis and exposed further to the heat treatment at 1000°C (12h). A detailed investigation on structural and functional properties of the as-prepared and heat treated particles was conducted in a comparative manner. High-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRPD) and focus ion beam milling (FIB) revealed in a great consistency the poorly crystallized and porous nature of the as-prepared particles. Well-crystallized coarser primary nanocrystals of Y2O3:Eu3+and Ag, which are hierarchically organized in dense spherical Ag@Y2O3:Eu3+ phosphor particles, were obtained through the heat treatment. Along with the change of structural properties, down conversion (red luminescence at 612nm owing to the Eu3+5D0→7F2 electric dipole transition) and mechanical endurance were enhanced 4-fold and 5-fold via heat treatment, respectively. This comparative study implies a good correlation between mechanical and luminescence behavior of phosphors, both strongly influenced by the particles structural properties