Structural Adjustment And Red Emission Enhancement Of A₃MgSi₂O₈:Eu²⁺,Mn²⁺（A=Ba、Sr、Ca） Phosphor

In this thesis, we focus on the red emitting enhancement of the phosphor constituted by(Ba, Sr, Ca)3Mg Si2O8: Eu2+, Mn2+ fluorescent material. Several preparation methods were conducted to fabricate these materials, and the following results have been obtained.A. Solid-solution-phased Ba1.75Ca1.25 Mg Si2O8: Eu2+, Mn2+(BCMS: EM) phosphors with photosynthetic action spectrum(PAS) in dual bands emission simultaneously peaked at 438 nm and 660 nm were demonstrated. The 660 nm-peaked red emission originated from Mn ion was achieved through an efficient energy-transfer(ET) from Eu ion, and the ET efficiency between Eu and Mn was calculated to be enhanced by 76 percent through the substitution of Ca for Ba in Ba3 Mg Si2O8. The enhancement of 660 nm red emission resulted by Ca solid solution showed great promise to construct PAS for bio-illumination.B. A dual band emission positioned at both 660 nm and 430 nm of(Ba, Sr)3Mg Si2O8: Eu2+, Mn2+ phosphor was achieved via spray-combustion synthesis procedure. At a specific limited solid solubility composition Ba1.3 Sr1.7Mg Si2O8, the secondary phases of(Ba, Sr)2Si O4 or(Ba, Sr)Mg Si O4 were effectively suppressed to be free of green emission to give out the desired 660 nm broad emission. An enhancement of photoluminescence(PL) intensity for 660 nm red emission from Mn ion was observed in as-received samples by combustion synthesis, indicating an intrinsic promotion of energy transfer from Eu2+ to Mn2+ via lattice vibration in(Ba, Sr)3Mg Si2O8 host. The particle crystallizes in a size range from 5 to 20 mm depending on process parameter variation. A near ultraviolet LED illumination prototype packaged with as–prepared phosphor exhibits to be violet in color.C.Sol-gel-combustion procedure was applied to prepare a highly efficient(Ba, Sr)3Mg Si2O8:Eu2+, Mn2+ phosphor with a simutaneous 430/660 nm–featured or 430/505/660 nm band emission to indicate the possible occurrence of the metastable green-emitting phases or not. Through varying stoichiometric amount of Si O2 in raw material, their coexistence of metastable green emitting phase with the host phase tends to be sensitive and diversified. Laser Microzone Raman spectrum is used to look insight the lattice stretch and the preferential occupation of Ba2+ on Sr2+ sites in Sr3 Mg Si2O8 lattices. The local structure and its crystal field around Eu2+ are disturbed by distorted arrangement of cross-linked [Mg O6] octahedra and [Si O4] tetrahedra.