Preparation of Ba₂Mg(PO₄)₂:Eu Phosphors and Their Photoluminescence Properties Under UV Excitation

For possible applications as luminescent materials for white-light emission using UV-LEDs, Ba 2 Mg(PO 4 ) 2 :Eu 2+ phosphors were prepared by a solid state reaction.The photoluminescence properties of the phosphor were investigated under ultraviolet ray (UV) excitation.The prepared phosphor powders were characterized to from a single phase of a monoclinic crystalline structure by a powder X-ray diffraction analysis.In the photoluminescence spectra, the Ba 2 Mg(PO 4 ) 2 :Eu 2+ phosphor showed an intense emission band centered at the 584 nm wavelength due to the f-d transition of the Eu 2+ activator.The optimum concentration of Eu 2+ activator in the Ba 2 Mg(PO 4 ) 2 host, indicating the maximum emission intensity under the excitation of a 395 nm wavelength, was 5 at%.In addition, it was confirmed that the Eu 2+ ions are substituted at both Ba 2+ sites in the Ba 2 Mg(PO 4 ) 2 crystal.On the other hand, the critical distance of energy transfer between Eu 2+ ions in the Ba 2 Mg(PO 4 ) 2 host was evaluated to be approximately 19.3 Å.With increasing temperature, the emission intensity of the Ba 2 Mg(PO 4 ) 2 :Eu phosphor was considerably decreased and the central wavelength of the emission peak was shifted toward a short wavelength.