Morphology-controlled synthesis and luminescence properties of ScPO4·2H2O:Ln3+ nano/micro-crystals by a facile approach

Abstract

Well-crystallized and uniform ScPO₄·2H₂O and ScPO₄·2H₂O:Ln³⁺ (Ln = Ce, Eu, Tb, Lu) nano/micro-crystals with multiform morphologies, such as sphere, hexagonal plate, diamond, four-angle star, butterfly-shaped and cuboid, have been successfully synthesized by a facile hydrothermal route without any surfactant molecules. XRD, FE-SEM, TEM, PL and kinetic decay were used to characterize the as-prepared products. The size and morphology of ScPO₄·2H₂O can be determined by the pH value, reaction time, reaction temperature, additive and doping of lanthanide ions. In particular, Ln³⁺ doping not only has a crucial role in the morphology of ScPO₄·2H₂O, but also affects its luminescence properties. The ScPO₄·2H₂O:Tb³⁺ and ScPO₄·2H₂O:Ce³⁺ samples display intense green and blue emissions, respectively. More importantly, the luminescence properties are closely related to morphologies and crystallinity. It can be found that the ScPO₄·2H₂O:Tb³⁺ sample with a hexagonal plate-like morphology possesses much higher emission intensity than those with other morphologies because of its larger anisotropic geometry. ScPO₄:Ln³⁺ crystals will become promising candidates for a variety of applications in down/up-conversion luminescence, magnets, lasers, and bio-labeling.