La_(0.8)Y_(0.2)PO_4:Bi^(3+),Sm^(3+),Eu^(3+)荧光粉的合成,性能及其前驱体热分解动力学

Synthesis,properties of La_(0.8)Y_(0.2)PO_4:Bi^(3+),Sm^(3+),Eu^(3+) phosphor and thermal decomposition kinetics of its precursor

相对于绿色和蓝色荧光粉,红色荧光粉因不能有效吸收近紫外光,致使发射的红光强度不能与蓝、绿两种荧光粉的发光强度同步,影响了其显色性,降低了发光效率.为获得能够被近紫外光高效激发的红色荧光粉,本文以硝酸铕、硝酸钐、氯化铋、氧化镧、氧化钇、磷酸三铵为原料,经高温固相反应合成得到Bi,Sm,Eu掺杂磷酸镧钇荧光粉,利用XRD,SEM,荧光光谱及TG/DTG对产物进行了表征,并采用非等温法研究前驱体的热分解过程,进而探究前驱体热分解反应过程的动力学及焙烧过程中荧光粉的形成机理.研究表明:Bi3+的最佳掺杂浓度为x=0.03,所得产物为以磁偶极(5D0→7F1)跃迁为主导发射的红色荧光粉;最佳产物与未掺杂产物相比,前者的荧光强度是后者的2.66倍;最佳产物前驱体的热分解过程只有一步失重,经计算获得了该过程对应的活化能、机理函数及指前因子.Bi,Sm,Eu掺杂磷酸镧钇荧光粉是一种发光效率高、具有广泛应用前景的近紫外激发白光LED用红色荧光粉.

Compared with green and blue phosphors,red phosphors can not effectively absorb near ultraviolet light,the emission red light intensity can not be synchronized with intensity of the blue and green phosphor,which affects their the color rendering and reduces the luminous efficiency.In order to obtain a red phosphor that can be efficiently excited by near ultraviolet light,Bi,Sm,Eu codoped lanthanum yttrium phosphate phosphors were synthesized by high temperature solid-state reaction with samarium nitrate, bismuth chloride, lanthanum oxide, yttrium oxide,tri-ammonium phosphate as raw materials. The products were characterized by XRD,SEM,PLEPL and TG/DTG. The thermal decomposition process of the precursors was studied by non-isothermal method. Then,the kinetics of the thermal decomposition reaction process and the formation mechanism of the phosphor during calcination were studied.The results show that the optimal doping concentration of Bi（3＋） is x = 0. 03,which leads to forming phosphor with magnetic dipole（5 D0→7 F1） transition as dominant emission. When the optimal sample was compared with non-doped sample,the fluorescence intensity of the former is 2.66 times higher than that of the latter. The thermal decomposition of the precursor for the optimal sample was carried out in one weight loss process. The thermal decomposition of the precursor for the optimal sample was carried out in one weight loss process. Activation energy,mechanism function and pre-exponential factor were got via calculation. So,the Bi,Sm,Eu codoped lanthanum yttrium phosphate phosphors are a kind of red phosphors with high luminous efficiency and great application prospect for UV-based white LED.