Luminescent properties of Bi3+-activated Ca2Sb2O7 nano-phosphor prepared by co-precipitation method

A series of Ca2Sb2O7:xBi3+ (x = 0, 0.5, 1, 1.5, 2, 4 and 8 mol%) blue phosphors were synthesized using a chemical co-precipitation technique with further calcination. The X-ray diffraction (XRD) and scanning electron microscope (SEM) results revealed that the obtained Ca2Sb2O7:xBi samples are orthorhombic weberite structure with particle size ranging from 20 nm to 40 nm. X-ray photoelectron spectroscopy (XPS) confirmed that the introduction of bismuth into the Ca2Sb2O7 crystal was in the form of Bi3+ and no other chemical states were found. The Bi-doped Ca2Sb2O7 powders exhibit a broad emission band centered at 438 nm upon UV-irradiation and it is characterized by double-luminescence centers. The dependence of the luminescent intensity on the Bi-doping concentration in Ca2Sb2O7 was studied in detail. As a result, the optimized concentration of Bi3+ is 1.5 mol% for the highest emission intensity peaking at 438 nm, and the concentration quenching occurs when the concentration of Bi3+ exceeds 1.5 mol%. The luminescence mechanism of Bi3+ in Ca2Sb2O7 was also discussed. The favorable luminescent properties of Ca2Sb2O7:Bi3+ make it promising for lighting and display applications.