Enhanced red emission from BaMoO 4 : Eu 3+ by Bi 3+ co-doping.

A series of Bi3+ ,Eu3+ -doped BaMoO4 phosphors was synthesized using a hydrothermal method. The crystal structure, morphology and optical properties of the phosphors were studied using X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence (PL) measurements. Three different particle morphologies were detected in the SEM observation. The energy dispersive spectroscopy (EDS) results indicated that the solubility of Bi3+ in spherical or rugby-like BaMoO4 particles was very low and the excess Bi3+ element was cumulated in the irregular particles. Characteristic emissions of Eu3+ ions (5 D0  → 7 FJ ; J = 0, 1, 2, 3, 4) were observed under excitation in ultraviolet (UV) light, with the most intense transition being the 5 D0  → 7 F2 transition. Energy transfer from MoO4 2- and Bi3+ to Eu3+ can be readily achieved. Red emission intensity of Eu3+ was enhanced by a factor of two by co-doping with a small amount of Bi3+ . Optical properties as a function of Bi3+ content were studied and the optimum Bi3+ content in BaMoO4 nanocrystals was determined to be 0.4 mol%.