硼置换铝对CaAl_2Si_2O_8:Eu^(2+)结构和发光特性的影响

Effect of Substituting B for Al on Structure and Spectral Properties of Phosphors CaAl_2Si_2O_8:Eu_(2+)

采用高温固相法在弱还原气氛下制备Ca0.955Al2-xBxSi2O8:Eu2+(x=0～0.7)系列荧光粉,研究BⅢ置换AlⅢ对晶体结构和光谱特性的影响。BⅢ以类质同相替代CaAl2Si2O8晶格中的AlⅢ形成连续固溶体,晶胞参数a,b,c,γ和晶胞体积V呈线性递减,而晶面夹角α,β呈线性递增。荧光激发谱为225～420nm宽带激发谱,半高宽为112nm,表观峰位于352nm,随着BⅢ置换量的增加,半高宽从112nm减小到95nm。发射光谱位于370～600nm,可由423和460nm两峰拟合而成,表观峰值位于425nm,随着BⅢ置换量的增加,两拟合峰均线性蓝移,且拟合峰强度比呈线性递减。

A series of luminescence phosphors Ca0.955Al2-xBxSi2O 8：Eu2＋（x=0～0.7） were prepared by solid-state reaction in weak reductive atmosphere.The lattice positions and the luminescent mechanism of Eu 2＋ in the host were discussed.The effects of B Ⅲ-substitution on the host lattices and spectral properties were also investigated.It is found that when B Ⅲ enters CaAl2 Si2O8 lattice and substitutes Al Ⅲ,complete solid solutions are formed in the whole range of x = 0～0.7.The lattice parameters（a,b,c,γ） and unit cell volumes of phosphors Ca 0.955Al2-xGaxSi2O8：Eu 2＋（x=0～1.0） decrease linearly and the lattice parameters（α,β） increase linearly as B Ⅲ content increases.A broad excitation spectrum consists of four excitation bands,which are located between 225 nm and 420 nm,the maximum excitation wavelength of which is at 352 nm,and FWHM decreases from 112 nm to 95 nm with the increase of the substitution amount of B Ⅲ.The emission spectrum,which is also a broad band between 370 nm and 600 nm,can be fitted by two peaks at 423 nm and 460 nm and its apparent peak is at 425 nm.Two fitted peaks are blue shifted,and the intensity ratio of the fitted peaks decreases linearly with increasing of the amount of B Ⅲ-substitution.