Preparation And Luminescence Properties Of Mn⁴⁺-doped Gallate Red Phosphors

White Light emitting diodes?WLEDs?,the fourth generation of novel lighting devices,become a research hotspot in the field of lighting which is describe to its high luminous efficiency,low energy consumption,long life and environmental protection.The stratege to obtain white light emission for commercial WLEDs is the combination of LED chip with YAG phosphors.Phosphors have great influence on the light color,attenuation life,quantum efficiency and color index of WLEDs.So far,the red phosphors used in WLEDs are less efficient than other phosphors used.Therefore,it is important to research and development new red phosphors with high quantum efficiency and high thermal stability.In this paper,new Mn⁴⁺-doped gallate red phosphors were prepared and their luminescent properties were studied in detail.?1?Phosphor Ca₁₄Zn₆Ga_10-xAl_xO₃₅:0.15Mn⁴⁺?0?x?10?were synthesized by solid state reaction method.Phase composition,fluorescence characteristics,thermal stability and different energy transfer mechanisms of samples were explored in detail.Broadband blue light emission from 370 nm to 500 nm of Ca₁₄Zn₆Ga₁₀O₃₅5 was observed at first time.The internal quantum efficiency and the external quantum efficiency of Ca₁₄Zn₆Ga_9.85O₃₅:0.15Mn⁴⁺were measured as high as 64.4%and 56.2%respectively,the external quantum efficiency of which is the highest in currently reported Mn⁴⁺-doped oxide phosphors.Energy transfer From Ca₁₄Zn₆Ga₁₀O₃₅5 to Dy³⁺ion and from Dy³⁺ion to Mn⁴⁺ion are found,both of which were proved to be the dipole-dipole interaction.With different Dy³⁺and Mn⁴⁺doping ratio,luminescent areas of Ca₁₄Zn₆Ga₁₀O₃₅:Dy³⁺,Mn⁴⁺can change from deep blue to deep red.Phosphor Ca_13.9Zn₆Ga_9.85O₃₅:0.1Dy³⁺,0.15Mn⁴⁺possess high color index?Ra=87?and low color temperature 3522K,showing a wide application prospect in the field of illumination.?2?Solid solution Ca₁₄Zn₆Ga_10-x0-x Al_xO₃₅:0.15Mn⁴⁺?0?x?10?were synthesized by solid state reaction method.Crystal structure,phase and luminescence properties were explored in detail.The band width energy gap increases with the x value due to stronger electronegativity of Al³⁺ion.The PLE peak of ⁴A₂?⁴T₁ and ⁴A₂?⁴T₂ transitions move to short wave with increased Al³⁺content,analyzed by Configuration diagram,due to the enhancement of Mn⁴⁺-O^2-Covalent bonding.Luminescent intensity increases before x=4then decrease,while lifetime singlely increases with increased x value.The internal quantum efficiency and the external quantum efficiency of phosphor Ca₁₄Zn₆Ga₆Al₄O₃₅:0.15Mn⁴⁺reach 26.1%and 40.3%respectively,the external quantum efficiency of which is the highest in currently reported Mn⁴⁺-doped oxide phosphors excited at 466nm.