Combustion synthesis of CaSc 2O 4:Ce 3+ nano-phosphors in a closed system

Abstract

The CaSc 2O 4:Ce 3+ nano-phosphors were successfully prepared by a single-step combustion method at an ignition temperature as low as 200 °C in a closed autoclave using glycine as a fuel and PEG4000 as a dispersant. The samples were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results revealed that CaSc 2O 4:Ce 3+ nano-phosphors can be conveniently prepared at an ignition temperature as low as 200 °C, which was much lower than that in the ordinary combustion methods. The optimized ignition temperature was 220 °C. The CaSc 2O 4:Ce 3+ nano-phosphors give a uniform particle size in the range of 15–20 nm. The low ignition temperature and the addition of PEG4000 dispersant play important roles in the formation of small sized nanoparticles. The as-prepared nano-phosphors were incompact aggregates, but highly dispersed nano-phosphors can be obtained after further ultrasonic treatment. The CaSc 2O 4:Ce 3+ nano-phosphors give satisfactory luminescence characteristic benefiting from the closed circumstance, in which cerium atoms can be isolated from the oxidizing atmosphere and non-fluorescent Ce 4+ ions can be ruled out. The present highly dispersed CaSc 2O 4:Ce 3+ nano-phosphors with efficient fluorescence are promising in the field of biological labeling, and the present low temperature combustion method is facile and convenient and can be applied as a universal process for preparing non-aggregate oxide nano-phosphors, especially those being sensitive to air at high temperature.