Crystal Structure and Photoluminescence Evolution of La5 (Si2+ x B1–x)(O13–x N x): Ce3+ Solid Solution Phosphors

Abstract

A series of iso-structural La-5(Si2+xB1-x)(O13-xNx):Ce3+ phosphors with apatite structure have been prepared. A combination of powder X-ray diffraction and neutron scattering technique was employed to explore the crystal structural evolution and the rigid nature from oxy- to oxynitride-based apatites, and some local structures were also characterized by HRTEM and Si-29 NMR data, respectively. The new La-5(Si2+xB1-x)(O13-xNx):Ce3+ solid solution phosphors gave continuously controlled emission from 421 nm [La5Si2BO13:Ce3+, end-member (x = 0)] to 463 nm (La(5)Si3O12N:Ce3+, end-member (x = 1)). Substitution of B3+ and O-2 by Si4+ and N-3 in La-5(Si2+xB1-x)(O13-xNx):Ce3+ phosphors produced more covalency into the crystal field environment around the Ce3+ ions inducing the red-shifted emission, further improving the thermal stability of the oxynitride-based apatite phosphors. The proposed approach from oxy- to oxynitride based iso-structural phases could significantly contribute to future research in designing complex solid solution phosphors.