Synthesis and photoluminescence study of narrow-band UVB-emitting LiSr4(BO3)3:Gd3+, Pr3+ phosphor

Abstract

A series of Pr 3+ , Gd 3+ and Pr 3+-Gd 3+-doped inorganic borate phosphors LiSr 4 (BO 3) 3 were successfully synthesized by a modified solid-state diffusion method. The crystal structures and the phase purities of samples were characterized by powder X-ray diffraction. Surface morphology of the sample was studied by scanning electronic microscopy (SEM). The optimal concentrations of dopant Gd 3+ ions in compound LiSr 4 (BO 3) 3 were determined through the measurements of photoluminescence (PL) spectra of phosphors. Gd 3+-doped phosphors LiSr 4 (BO 3) 3 show strong band absorption in UV spectral region and narrow-band UVB emission under the excitation of 276 nm was only due to 6 P J → 8 S 7/2 transition of Gd 3+ ions. The effect of Pr 3+ ion on excitation of LiSr 4 (BO 3) 3 :Gd 3+ was also studied. The excitation of LiSr 4 (BO 3) 3 :Gd 3+ , Pr 3+ gives a broad-band spectra, which show very good overlap with the Hg 253.7 nm line. The photoluminescence spectra of LiSr 4 (BO 3) 3 with different doping concentrations Pr 3+ and keeping the concentration of Gd 3+ constant at 0.03 mol have also been studied. The emission intensity of LiSr 4 (BO 3) 3 :Pr 3+-Gd 3+ phosphors increases with increasing Pr 3+ doping concentration and reaches a maximum at 0.01 mol. From the photoluminescence study of LiSr 4 (BO 3) 3 :Gd 3+ , Pr 3+ we conclude that there was efficient energy transfer from Pr 3+ → Gd 3+ ions in LiSr 4−x−y Pr x Gd y (BO 3) 3 phosphors.

Combustion Synthesis and Photoluminescence Study of Sr3Y1-x(BO3)3: xPr3+ (0.01 ? x ? 0.05) Red Borate Phosphor for Near Blue Pumped WLED

“…LiSr 4 (BO 3 ) 3 : Pr 3+ phosphor shows broad excitation band from 210 to 260 nm with a maximum at 245 nm. The phosphors give strong and a much broader emission spectrum from 260 to 370 nm having two shoulder peaks at 280 and 325 nm under the excitation of 245 nm (7). Role of Pr 3+ in various hosts is different due to crystal field energy.…”