Synthesis and spectral analysis of novel yellowish-green emitting phosphors Sr_2MgSi_3O_9:Tb~(3+),Ce~(3+)

Novel phosphors Sr2MgSi3O9:Tb3+ and Sr2MgSi3O9:Tb3+,Ce3+ were synthesized by gel-combustion method in weak reductive environment.The as-synthesized phosphors were investigated by XRD,SEM and fluorescence spectrophotometer.The results show that Sr2MgSi3O9:Tb3+ and Sr2MgSi3O9:Tb3+,Ce3+ phosphors possess the similar tetragonal crystal structure as that of Sr2MgSi2O7.The initial particles of as-synthesized phosphors are nearly spherical in shape,and the particle size is about 100nm in diameter.The excitation spectrum of Sr2MgSi3O9:Tb3+ is a broad band and the main peak is at 249nm.The emission spectrum is composed of a series of peaks,located respectively at 473,491,547 and 585nm.The main peak is at 473nm(5D3→7F3),and the secondary peak is at 547nm(5D4→7F5).The excitation spectrum of Sr1.955MgSi3O9:Tb3+0.04,Ce3+0.005 displays two broad bands with two peaks around 249 and 335nm respectively;the latter peak is much stronger than the former.Under 335nm irradiation,the emission spectrum is composed of two parts.One part is a broad band at around 400nm,which belongs to the emission of Ce3+.The other part is composed of a series of peaks,located respectively at 491,547 and 588nm.These emission peaks are ascribed respectively to Tb3+ ions transition of 5D4→7FJ(J= 6,5,4) in Sr2MgSi3O9:Tb3+,Ce3+.The main emission peak is at 547nm(5D4→7F5).Moreover,the effect of Ce3+ doping amount on luminescent intensity was discussed.It is found that energy transfer from Ce3+ to Tb3+ is efficient and sensitization lie in Ce3+ to Tb3+ in Sr2MgSi3O9 host under UV light.