Synthesis of new red emitting phosphors based on rare earth oxycarbonates

Enhancement of the luminescent intensity of the green emitting Gd2O2CO3:Tb phosphor

“…The diffraction patterns of the samples calcined at 973 K or less were in good agreement with that of a single phase of the hexagonal rare earth oxycarbonate (type II) and no impurity peak was observed. Although a small amount of potassium (<1 mol%) was detected by the XRF analysis in the samples, the luminescent properties of the oxycarbonate phosphors are not affected by the nominal flux remained in the samples [6][7][8][9][10]. On the contrary, the XRD pattern of the sample calcined at 1023 K corresponded to that of cubic Gd 2 O 3 and the color became a tinge of brown, which suggests that a part of terbium ions exists in the tetravalent state.…”

“…The Eu 3+ -or Tb 3+ -doped II-RE 2 O 2 CO 3 (RE = La, Gd, and Y) phosphors prepared by our flux method showed high emission intensities despite that the particle size was in a submicron scale [6][7][8][9][10]. In the series of the oxycarbonate phosphors examined, II-Gd 2 O 2 CO 3 :17 at.%Tb 3+ exhibited the highest relative emission intensity, which was 101% of that of a commercial LaPO 4 :Ce 3+ ,Tb 3+ phosphor [8,9].…”

Enhanced luminescent properties of Ca3−Tb ZrSi2O9+/2 phosphors by Al3+ doping into the Zr4+ site in the host lattice

“…In a layered structure, it is well known that energy transfer from one excited luminescent ion to another across the anion groups is inhibited by the long distance between cations. Therefore, phosphors based on layered structure should be resistant to concentration quenching, even if a large amount of activator is introduced into the host lattice [8,[13][14][15][16][17][18][19][20]. In addition, silicate materials have high thermal and chemical stabilities, low cost, and excellent waterresistance [21][22][23].…”

Synthesis and luminescence properties of the lithium-containing lanthanum-oxycarbonate-like borates

“…The green-emitting phosphors Gd 2 O 2 CO 3 :Tb 3 þ and (Gd 0.95 Y 0.05 ) 2 O 2 CO 3 :Tb 3 þ exhibited high relative emission intensity, which was 111% and 131% of that of a commercial LaPO 4 :Ce 3 þ ,Tb 3 þ phosphor, respectively [2,17]. Type II La 2 O 2 CO 3 :Eu 3 þ , Gd 2 O 2 CO 3 :Eu 3 þ , and Y 2 O 2 CO 3 :Eu 3 þ have been synthesized and studied as red phosphors [18]. Among these phosphors, the most efficiency emission was obtained at the composition of R 2 O 2 CO 3 : 7% Eu 3 þ (R ¼La, Gd, and Y), and the corresponding emission intensities to that of the commercial Y 2 O 3 :Eu 3 þ phosphor were 23%, 27% and 22% for La, Gd and Y, respectively.…”

“…Among these phosphors, the most efficiency emission was obtained at the composition of R 2 O 2 CO 3 : 7% Eu 3 þ (R ¼La, Gd, and Y), and the corresponding emission intensities to that of the commercial Y 2 O 3 :Eu 3 þ phosphor were 23%, 27% and 22% for La, Gd and Y, respectively. It has been found that the charge transfer bands between Eu 3 þ (4f) and O 2 À (2p) are dominant in some Eu 3 þ doped type II R 2 O 2 CO 3 (R ¼Y, La and Gd) compounds [18]. In the layer structure, energy transfer from a luminescent center to another one across the CO 3 2 À layer is probably forbidden because of the long R 3 þ -R 3 þ distance.…”