Versatile luminescence of Eu^2+,3+-activated fluorosilicate apatites M_2Y_3[SiO_4]_3F (M = Sr, Ba) suitable for white light emitting diodes

Abstract

Eu-doped fluorosilicate apatites M 2 Y 3 [SiO 4 ] 3 F (M = Sr, Ba) are prepared by solid state reaction. Unlike conventional Eu-doped materials, coexistence of Eu 3+ and Eu 2+ ions is found from the photoluminescence of Eu-doped apatites M 2 Y 3 [SiO 4 ] 3 F (M = Sr, Ba) which were prepared in reducing atmosphere. Eu 2+ ions are converted from Eu 3+ ions in the reduction process. It is suggested that Eu 2+ ions occupy A(I) (4f) or A(II) (6h) crystallographic site in the apatite lattices. Intense emission lines due to Eu 3+ are observed at 600-630 nm, while broad emission band due to Eu 2+ is observed at 450-650 nm. These emissions combined with blue emission from LED are suitable to obtain white light, i.e., white LEDs for lighting and display. Different luminescence characteristics are obtained between Sr 2 Y 3 [SiO 4 ] 3 F:Eu and Ba 2 Y 3 [SiO 4 ] 3 F:Eu, which were prepared in reducing atmosphere.

Photoluminescence characteristics of high thermal stable fluorosilicate apatite Ba2Y3(SiO4)3F:Sm3+ orange-red emitting phosphor

“…It can be observed that all of the excitation spectra have the same profile in addition to the intensity. Qi et al [29] prepared Eu 3 þ -doped Ba 2 Y 3 (SiO 4 ) 3 F and found the charge transfer band (CTB) of Eu-O at 255 nm. Blasse and Brill [35] found that the CTB energy of Sm 3 þ in compounds always appears 1.170.1 eV higher than that of Eu 3 þ .…”

“…With the increase in Ce 3 þ doping concentration, the maximum emission wavelength from to the 5d to 4f transition on Ce 3 þ ions in Ba 2 Y 3À x Ce x (SiO 4 ) 3 F shows a redshift from 405 nm (x¼ 0.005) to 460 nm (x¼ 0.07). Huang et al reported the two kinds of luminescence centers give a broad band in a spectral range from blue to red in Ba 2 Y 3 (SiO 4 ) 3 F:Eu 3 þ ,Eu 2 þ phosphors [29]. However, to our knowledge, there has been no report on the luminescence properties of Sm 3 þ -doped Ba 2 Y 3 (SiO 4 ) 3 F apatite phosphor.…”

Defect induced “super mop” like behaviour of Eu3+-doped hierarchical Bi2SiO5nanoparticles for improved catalytic and adsorptive behaviour

“…A broad peak centred at 496 nm and 514 nm corresponding to the transition 4f 6 5d 1 -4f 7 has been observed corresponding to Eu 2+ . [53][54][55] As the amount of Eu doping was very miniscule, the doping amount was increased to 2.5% to obtain a relatively higher intensity of emission. Furthermore, relatively weaker peaks at 595 nm, 616 nm, 653 nm and 703 nm, characteristic of Eu 3+ , were also observed in the photoluminescence spectra of the materials.…”

Crystal growth, structural characterization and high temperature behavior of Na3TmSi3O9

“…Rare earth element (REE) containing silicates are one class of inorganic metal oxide-based phosphors that have been intensively studied for these purposes. Examples include garnets such as Ca 3 Sc 2 Si 3 O 12 :REE 3+ [2][3][4], the group of M 2 SiO 4 : REE 3+ (M:Ca, Sr, Ba) compounds [5][6][7] or apatites such as Ca 2 Gd 8 -(SiO 4 ) 6 O 2 :Er 3+ , Ca 4 Y 6 (SiO 4 ) 6 O:Eu 3+ and M 4 Y 6 [SiO 4 ] 6 F 2 :Eu 2+,3+ (M: Sr, Ba) [8][9][10]. Another promising silicate material that allowed a wide-range tuning of the optical properties from blue emitters and IR S-band amplifiers to X-ray phosphors depending on the type and the content of the REE cation was reported by Ananias et al [11]: Na 3 (Y 1-x M x )Si 3 O 9 (M:Tm 3+ , Tb 3+ ; x = 0-1).…”