The Study On Luminescence Properties Of M₂SiO₄: Dy³⁺ (M=Ca, Sr, Ba) Phosphors

White LED has attracted much interest in the field of illumination due to its own superiorities such as low voltage, long lifetime, environmental protection, and so on. The single matrix white light phosphor becomes the focus of light conversion materials' research because of its stability of color and good property of color deoxidization.M₂SiO₄: Dy³⁺(M=Ca, Sr, Ba) phosphors for WLED were prepared by high temperature solid-state reaction method. The structure and emission spectrum excited by near violet light were investigated. The X-ray power diffraction data of M₂SiO₄:Dy³⁺(M=Ca, Sr, Ba) are in agreement of JCPDS standard card which indicates that single phase M₂SiO₄: Dy³⁺(M=Ca, Sr, Ba) phosphors can be obtained by such synthesis process.The excitation spectra of M₂SiO₄: Dy³⁺ show strong absorption near 325nm,350nm,365nm and 386nm due to ⁶H_15/2â†'⁶P_3/2,⁶H_15/2â†'⁶P_7/2,⁶H_15/2â†'⁶P_5/2,⁶H_15/2â†'⁴M_21/2transition of Dy³⁺. The emission light is at about 479nm,491nm,571nm under 386nm UV excitation. The emission at 479nm and 491nm (Blue) attribute to the ⁴F_9/2â†'⁶H_15/2 transition and 571nm (Yellow) attributes to the ⁴F_9/2â†'⁶H_13/2 transition. White light is generated by mixing the two colors. The color coordinates(CIE) analysis indicates Ca₂SiO₄:Dy³⁺ is located at (0.30, 0.33) which is near white color region.The emission spectrum of Eu³⁺ and Dy³⁺ co-doped M₂SiO₄ phosphors under UV excitation were investigated for enhancing red emission. The emission spectrum consists of three bands. The blue and yellow band attribute to Dy³⁺ ions and the red band from 610nm to 620nm attributes to the ⁵D₀—⁷F₂ transition of Eu³⁺ ions. The emission intensity of red band is enhanced comparatively.Still we prepared and analyzed (Sr_1-xM_x)₂SiO₄: Dy³⁺(M=Ca, Ba) phosphors for their change rules of Y/B ratio under UV excitation. The increase of Ca²⁺ ions in (Sr_1-xCa_x) ₂SiO₄: Dy³⁺ made the whole emission spectrum enhanced and the Y/B ratio is increased from 0.46 to 0.92. The increase of Ba²⁺ ions in (Sr_1-xBa_x)₂SiO₄: Dy³⁺ made the blue band emission declined while the yellow band and Y/B ratio is are increased first then declined.As a result, the emission intensity of the yellow band can be controlled by changing the sort and content of the alkaline-earth metals thus the color coordinates of the phosphors will located at the white light region. This is significant for the spectrum characteristic study of Dy³⁺ ions doped phosphors.There are 22 figures, 5 tables and 42 references in this paper.