红色荧光粉BaAl_2Si_2O_8:Eu^(3+),Li^+的制备和发光性能研究

Preparation and Luminescent Properties of Red Phosphor BaAl_2Si_2O_8:Eu^(3+),Li^+

通过高温固相法合成了红色荧光粉系列Ba_(1-x)Al_2Si_2O_8:Eu_x^(3+),Li_(0.03)^+,并系统地研究了该系列荧光粉的晶体结构和发光性质的变化。合成的试样均为BaAl_2Si_2O_8晶体,均单斜晶系,空间群为C2/m(12)。Eu^(3+)取代Ba^(2+)格位进入基质BaAl_2Si_2O_8晶体,造成了基质晶胞参数a,b,c和晶胞体积V相应地减小,只引起了基质晶体结构轻微的畸变。试样的激发光谱位于220 nm^550 nm,由一个宽带激发谱和一组锐线峰带构成,激发光谱中的最强峰为393 nm(~7F_0→~5L_6)。通过393 nm波段对系列试样进行有效激发,收集到发射光谱均位于550 nm^750 nm,且由发射光谱中出现多条锐线峰,在614 nm(~5D_0→~7F_2)处发射峰最强,Eu^(3+)的595 nm(~5D_0→~7F_1)发射峰劈裂产生了590 nm、595 nm和599 nm处的三个分裂峰,而614 nm(~5D_0→~7F_2)发射峰劈裂为614 nm、617 nm、619 nm、622 nm和627 nm处的五个分裂峰,Eu^(3+)取代Ba^(2+)进入基质晶格BaAl_2Si_2O_8中,与其临近的氧配体形成了C2的点群对称性和Eu^(3+)主要占据非反演对称中心格位。系统研究了该系列荧光粉发光性能与掺杂离子Eu^(3+)浓度的关联。研究结果显示,当掺杂离子Eu^(3+)浓度x≤0.03时,荧光粉的发光强度随着掺杂离子Eu^(3+)浓度x的增加而增加,当x>0.03时,随x的增加而减小。试样的色坐标不随掺杂离子Eu^(3+)浓度改变而改变;该系列荧光粉浓度淬灭机理为电偶极–电偶极相互作用。

A series of red phosphors Ba1-xAl2Si2O8：Eux^3＋,Li0.03^＋ were prepared by high temperature solid-state reaction. Structure and luminescence properties of the Ba1-xAl2Si2O8：Eux^3＋,Li0.03^＋ were studied. The samples are a pure phase of BaAl2Si2O8 ,both of them belong to monoclinie system, and C2/m （12） space group. Eu^3＋ substituted Ba^2＋ sites into BaAl2Si2O8, which makes the lattice parameters （a ,b ,c） and the unit cell volume（V） decreases correspondingly, only attracted minor matrix crystal structure distortion. The excitation spectra are composed of a broad excitation band which located at 220 nm -550 nm and a group of sharp peaks, the strongest peak is 393 nm （^7F0→^5L6）. The emission spectra are located at 550 nm - 750 nm, and present a number of sharp lines emission. The strongest peak is 614 nm （ ^5D0→^7F2 ）. 595 nm（ ^5D0→^7F1 ） can be deconvoluted to three peaks of 590 nm, 595 nm and 599 nm;614 nm（^5D0→^7F2 ） ean be deeonvoluted to five peaks of 614 nm,617 nm,619 nm,622 nm and 627 nm. Eu^3＋ replaced Ba^2＋ in the host lattice BaAl2Si2O8 , and near the oxygen ligands to forma C2 point group symmetry, Eu^3＋ ions mainly occupy the center of non inversion symmetry site. The effect of the doping concentration of Eu^3＋ was investigated. The result shows that the luminescent intensity firstly increases and then decreases with the increase of Eu^3＋ concentration, and reaches the maximal value at Eu^3＋ concentration of 0. 03 in mole, the color coordinates of samples with almost no change. The mechanism of concentration quenching is due to the dipole-dipole interaction.