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

A series of Bi ³⁺ ,Eu ³⁺ -doped BaMoO ₄ 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 Bi ³⁺ in spherical or rugby-like BaMoO ₄ particles was very low and the excess Bi ³⁺ element was cumulated in the irregular particles. Characteristic emissions of Eu ³⁺ ions ( ⁵ D ₀  →  ⁷ F _J ; J = 0, 1, 2, 3, 4) were observed under excitation in ultraviolet (UV) light, with the most intense transition being the ⁵ D ₀  →  ⁷ F ₂ transition. Energy transfer from MoO ₄ ^2- and Bi ³⁺ to Eu ³⁺ can be readily achieved. Red emission intensity of Eu ³⁺ was enhanced by a factor of two by co-doping with a small amount of Bi ³⁺ . Optical properties as a function of Bi ³⁺ content were studied and the optimum Bi ³⁺ content in BaMoO ₄ nanocrystals was determined to be 0.4 mol%.
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