Effect of ionic substitution (Ca/Sr/Ba) on structure and luminescent properties of Ce3+ doped fluorapatite

In this paper, Ce3+-activated iso-structural solid solutions La5.99Ce0.01M4(SiO4)6F2 (M = Ca, Sr and Ba) compounds were prepared for the first time. The structure and luminescence properties of the samples were investigated to explore the difference of cation substitution. The phase analysis indicated that all XRD peaks of the samples were indexed by a hexagonal cell with the space group of P63/m, and the phosphors showed strong blue light emission with broad bands. With the isomorphous substitution of Ba → Sr → Ca, the average bond length between Ce3+ and anions is decreased and the crystal field around Ce3+ is strengthened, resulting in the red-shift (from 410 nm to 423 nm) of the emission wavelength for La5.99Ce0.01M4(SiO4)6F2 (M = Ca, Sr, Ba).