Eu2+-activated Ba3Ca3(PO4)4 phosphor with doping-concentration dependent luminescence

A color tunable phosphor of Eu2+-activated monophosphate Ba3Ca3(PO4)4 was developed via facile solid-state reaction synthesis. The samples were tested by X-ray powder diffraction (XRD) patterns, morphological properties, luminescence and decay lifetime measurements. The structural characteristics were discussed. The excitation bands of the phosphors cover the UV-, near-UV and blue-wavelength bands extending from 300 to 440 nm. The luminescence spectra of the phosphors show a great dependence on the Eu2+-concentration in Ba3Ca3(PO4)4, which can give blue to yellow emission colors. There are two kinds of Eu2+ centers in Ba3Ca3(PO4)4 lattices, which give yellow (EuI) and blue (EuII) luminescence with the maximum wavelength at 565 nm and 450 nm, respectively. The structural occupations and luminescence properties of EuI and EuII centers were discussed. EuI (yellow center) has a dominant contribution to the total luminescence with the increase of the Eu2+-doping level. The luminescence internal quantum efficiency and thermal stability (activation energy) were reported. The reported results could be helpful for the further potential application of the phosphor.