Synthesis and Luminescent Properties of Eu3+-Doped NaCaPO4 Nano-Particles Under VUV–UV Excitation

Abstract

A red emitting phosphor, Eu(3+)-doped NaCaPO4, has been prepared by the sol-gel method. X-ray powder diffraction (XRD) analyses confirmed the pure crystalline phase of NaCaPO4. The morphologies of the phosphor were investigated by scanning electron microscopy (SEM), which indicated that the phosphor had a good quality of surface crystallization. This phosphor had the grain sizes of around 500 nm with fairly narrow size distribution. The vacuum ultraviolet (VUV) synchrotron radiation spectroscopy technique was used to study the luminescence properties of this phosphor. The excitation spectra revealed that there is an efficient energy transfer from the phosphate host to Eu3+ ions. Upon excitation with VUV and UV radiation, the phosphor showed strong red emission around 618 nm corresponding to the forced electric dipole 5D0 --> 7F2 transition of Eu3+ ions. Defects and micro-structures that related to Eu3+ ions in the phosphate host are discussed.