Correction for ‘Structure and luminescence properties of green-emitting NaBaScSi2O7:Eu2+ phosphors for near-UV-pumped light emitting diodes’ by Chengying Liu et al., J. Mater. Chem. C, 2013, 1, 7139–7147.

We present a combined structural analysis on the powder of the Ca2Al3O6F phase using X-ray diffraction (XRD) and Raman spectroscopy techniques. The crystal structure of Ca2Al3O6F has been refined in the rhombohedral system, R space group, a = 17.3237(7) Å, c = 7.00017(4) Å, V = 1819.38(2) Å3, Z = 6. The Ca2Al3O6F phase consists of almost ideal AlO4 tetrahedrons linked through corners, Ca2+ ions in voids, and F− ions disordered over 6 sites around the Ca2 ion. The two different Ca sites have also been verified by the photoluminescence spectrum and decay curves using Eu2+ as the probe ion substituted onto the Ca2+ sites. A lattice dynamics simulation based on the simplified version of the Born–Karman potential model has been produced. Calculated Raman phonon modes agree qualitatively well with the experimental data. The calculations show that the strong line at 538 cm−1 (Ag) corresponds to the vibrational mode of a six-membered AlO4 tetrahedrons ring, and the line at 572 cm−1 (Ag) corresponds to the full symmetric vibration of fluorine atoms in the ab crystal plane.

•Color-tunable blue–green La6Ba4(SiO4)6F2:Ce3+,Tb3+ phosphors were prepared.•The phase structures of the La6Ba4(SiO4)6F2 apatites compounds were analyzed.•Ce3+–Tb3+ energy transfer process and mechanism were discussed.A series of new luminescent emission-tunable phosphors La6Ba4(SiO4)6F2:Ce3+,Tb3+ with apatite structure have been synthesized by a high temperature solid-state reaction. X-ray diffraction, photoluminescence (PL) emission and excitation spectra, lifetime, as well as the effect of Tb3+ concentration were employed to characterize the resulting samples. The PL spectrum of La6Ba4(SiO4)6F2:Ce3+,Tb3+ phosphor contains both the asymmetric broad-band blue emission (Ce3+ ion) and the line-type green emission (Tb3+ ion). The increased Tb3+ concentration induced the emitting colors to shift from blue to green region by the naked eye. Meanwhile, the energy transfer between Ce3+ and Tb3+ is thoroughly investigated, and the energy-transfer efficiency from Ce3+ to Tb3+ ion is also calculated. The results indicated that these phosphors could be considered as double emission phosphors for n-UV excited white light-emitting diodes.

•Na2CaMg(PO4)2:Eu2+, Mn2+ phosphors with tunable luminescence were synthesized.•Energy transfer from the Eu2+ to Mn2+ ions occurs via a dipole–dipole mechanism.•Thermal quenching luminescence has been studied.Na2CaMg(PO4)2:Eu2+, Mn2+ phosphors were synthesized by a high temperature solid-state reaction. The phase and crystal structures were analyzed. The emission colour of Na2CaMg(PO4)2:Eu2+, Mn2+ phosphors varied from blue to red, which was controlled by altering the concentration ratio of Eu2+ to Mn2+. The photoluminescence and lifetime analysis indicate that there is an efficient energy transfer from the Eu2+ to Mn2+ ions via a dipole–dipole mechanism with the critical distance of ~11 Å. Thermal quenching luminescence results reveal that Na2CaMg(PO4)2:Eu2+,Mn2+ exhibits good thermal stability. Preliminary studies showed that the phosphor might be promising as a light-conversion phosphor for the near UV-pumped white-light LEDs.

A series of color-adjustable phosphors La5Si2BO13(LSBO):Ce3+,Mn2+ were synthesized through a high temperature solid-state method. The crystal structures of Ce3+ and Mn2+ doped La5Si2BO13 phosphors were refined by the Rietveld method, which were proved to be the apatite-type hexagonal phase (space group of P63/m). It was found that two different La3+ sites in the La5Si2BO13 phase were occupied evenly by Ce3+ and Mn2+ ions, and then the formed vacancy contributed to the charge compensation. La5Si2BO13:Ce3+,Mn2+ phosphors exhibited a broad excitation band ranging from 250 to 375 nm and two broad emission bands centred at 418 nm and 585 nm upon 345 nm excitation. It is found that the emission colors could be tuned from blue-violet (0.1629, 0.0523) to pink (0.3227, 0.1830) by changing the ratio of Ce3+/Mn2+. Moreover, the energy transfer mechanism was verified to be the dipole–dipole interaction, and the critical distance was calculated to be 10.02 Å by using the concentration quenching method.

•Blue-emitting phosphor K2Ca2Si2O7:Ce3+ was synthesized.•The critical quenching concentration and concentration quenching mechanism was discussed.•Ce3+ emission centre in K2Ca2Si2O7 were studied by the photoluminescence spectra and decay curves.A novel blue-emitting phosphor K2Ca2Si2O7:Ce3+ has been synthesized via a solid-state reaction. The pure phase structure of K2Ca2Si2O7:Ce3+ phosphor was investigated by using the XRD technique and Rietveld refinement. K2Ca1.98Si2O7:0.02Ce3+ phosphor exhibited broad-band blue emission peaking at 413 nm upon 291 nm excitation and 423 nm upon 338 nm excitation. The critical quenching concentration of Ce3+ was determined about 2 mol% and the corresponding concentration quenching mechanism was considered to be the dipole–dipole interaction. The double-exponential fluorescence decay curve was also discussed to verify the two kinds of Ce3+ centre in K2Ca2Si2O7 host.

•Orthorhombic terbium molybdate, β′-Tb2(MoO4)3 have been fabricated.•The crystal structure β′-Tb2(MoO4)3 has been refined by Rietveld method.•The Raman and luminescence spectrum of β′-Tb2(MoO4)3 has been measured.Orthorhombic terbium molybdate, β′-Tb2(MoO4)3, microcrystals have been fabricated by solid state synthesis at T = 750–1270 K for t = 290 h. The crystal structure β′-Tb2(MoO4)3 has been refined by Rietveld method in space group Pba2 with cell parameters of a = 10.35387(6), b = 10.38413(6) and c = 10.65695(7) Å (RB = 1.83%). About 40 narrow Raman lines have been observed in the Raman spectrum recorded for the β′-Tb2(MoO4)3 powder sample. The luminescence spectrum of β′-Tb2(MoO4)3 has been measured under the excitation at 355 nm, and the intensive photoluminescence band at 540–550 nm has been found.

Green-emitting phosphor Eu2+ doped NaBaScSi2O7 was synthesized by a solid-state reaction, and the photoluminescence properties were investigated in conjunction with a structural analysis. The crystallographic occupancy of Eu2+ in the Sc silicate NaBaScSi2O7 matrix was studied based on the Rietveld refinements results and the crystal chemistry rules. The optimum concentration of Eu2+ in the NaBaScSi2O7 phosphor was about 10 mol%, and the concentration quenching mechanism was verified to be the dipole–dipole interaction. Upon excitation at 365 nm, the composition-optimized NaBaScSi2O7:Eu2+ exhibited strong green light peaking at 501 nm with the CIE chromaticity (0.0706, 0.5540) and a high internal quantum efficiency of about 65%. The thermally stable luminescence properties were also studied and compared with those of the commercial green phosphors. A white light emitting diode (w-LED) lamp was finally fabricated by using the present green phosphor and the commercial blue and red phosphors, which exhibited a high color rendering index (Ra) of 86.5 at a correlated color temperature of 2528 K with CIE coordinates of x = 0.353, y = 0.324. These results suggest that NaBaScSi2O7:Eu2+ is a potential green phosphor candidate for near-UV-pumped w-LEDs.

A series of iso-structural green-emitting Na3(Y,Sc)Si3O9:Eu2+ phosphors with different Y/Sc ratios have been synthesized by a solid-state reaction. All of the phosphors exhibited strong broad absorption bands in the near ultraviolet (n-UV) range, and gave bright green emission upon 365 nm excitation light. As for the composition-optimized Na3Y0.3Sc0.7Si3O9:Eu2+ phosphor, the critical Eu2+ quenching concentration (QC) was determined to be about 3 mol%, and the corresponding QC mechanism was verified to be the dipole–quadrupole interaction. The fluorescence decay curves, temperature dependence photoluminescence and CIE value of Na3Y0.3Sc0.7Si3O9:Eu2+ phosphors were discussed. A white light-emitting diode (LED) lamp was fabricated based on the green-emitting Na3Y0.3Sc0.7Si3O9:Eu2+ phosphor and combining a 370 nm n-UV chip and the commercial blue-emitting BaMgAl10O17:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors. The produced white-light n-UV LED lamp gave CIE chromaticity coordinates of (0.3690, 0.3782), a high color rendering index of 85.6 and a warm color temperature of 2300 K.

Ce3+ and Ce3+/Tb3+-activated Y4Si2O7N2 phosphors are synthesized by the solid-state method, which can be efficiently excited by near ultraviolet (UV) light emitting diode (LED) chips. The PL spectrum of Y4Si2O7N2:Ce3+ shows a broad hump between 380 and 650 nm, assigned to the electron transition from the 4f energy level to different 5d sub levels of the Ce3+ ions at different Y3+ sites. The color of the Y4Si2O7N2:Ce3+ phosphor can shift from blue to green by introducing Tb3+. In addition, the energy transfer process from Ce3+ to Tb3+ in the Y4Si2O7N2 host was investigated and discussed in terms of both the luminescence spectra and decay curves. The energy transfer critical distance has been calculated and evaluated by the concentration quenching method. Therefore, the Ce3+ and Ce3+/Tb3+-activated Y4Si2O7N2 phosphors can serve as key materials for phosphor-converted white-light UV-LEDs.

The substituted activator ions Eu2+ in the β-Ca3(PO4)2-type structure, Ca9NaMg(PO4)7 compound, have been studied as emission centers, as well as structural probes. The crystal structure and crystallographic sites of Eu2+ in Ca9NaMg(PO4)7 have been identified by Rietveld refinements, electron paramagnetic resonance (EPR) spectroscopy analysis and combined photoluminescence spectral analysis, respectively. Ca9NaMg(PO4)7:Eu2+ phosphor exhibits a broad emission band in the visible light region with three distinguished peaks centered at 415, 458, and 615 nm, which are ascribed to different Eu2+ emission centers occupied in three different Ca crystallographic sites. The concentration quenching behavior, variation in lifetimes and the temperature dependent luminescence properties have been investigated as a function of different emission centers, 415, 458, and 625 nm for Ca9NaMg(PO4)7:Eu2+ phosphor. Accordingly, the relationship among three different Eu2+ luminescence centers originating from three different Ca2+ crystallographic sites has been found and verified.

•Rare-earth free self-activated and Eu3+ or Sm3+ doped vanadate phosphors Ca2NaZn2V3O12 were synthesized.•The pure-phase garnet structure was verified by the XRD Rietveld refinement.•The energy transfer behaviors from VO43− to Eu3+/Sm3+ ions have been demonstrated.Novel rare-earth free self-activated and Eu3+ or Sm3+ doped vanadate phosphors Ca2NaZn2V3O12 were synthesized via the solid-state reaction route. The pure-phase garnet structures in this system were verified by the X-ray diffraction (XRD) and Rietveld refinement. The self-activated luminescence and rare earth doped luminescence behaviors have been studied in detail. The broad-band green emission can be found from the as-prepared Ca2NaZn2V3O12 compound, originating from the VO43− emission. The energy transfer behaviors from VO43− to Eu3+/Sm3+ ions in Ca2NaZn2V3O12:A (A=Eu3+, Sm3+) phosphors have been demonstrated by photoluminescence (PL) and decay time measurement. All the results indicate that self-activated Ca2NaZn2V3O12 and the Eu3+ or Sm3+ doped Ca2NaZn2V3O12 phosphors show great potential for the application in the near-UV excited white LEDs.

We report a series of color-tunable Sr3.45Y6.5O2(PO4)1.5(SiO4)4.5:Eu2+,Mn2+ (SYPSO:Eu2+,Mn2+) phosphors in this work. The photoluminescence excitation and emission spectra, lifetime, and concentration-dependent effect were investigated, respectively. The energy transfer (ET) mechanism was verified as the dipole–dipole interaction, and the ET efficiency as well as the critical distance is also estimated. The emission colors of the obtained phosphors can be tuned from green to yellow by controlling the doping content of the Mn2+ ions with the fixed Eu2+ content. These results indicate that SYPSO:Eu2+,Mn2+ can be acted as a good candidate for the application in white light-emitting diodes.

The structural properties of clinopyroxene NaScSi2O6 have been investigated using the X-ray powder diffraction refinement, and the luminescence properties of Eu2+ and Eu2+/Mn2+-activated NaScSi2O6 have been studied to explore the new materials for phosphor-converted white light ultraviolet light-emitting diodes (UV-LEDs). Eu2+ was introduced into the NaScSi2O6 host in the reducing atmosphere, and the preferred crystallographic positions of the Eu2+ ions were determined based on the different structural models of the NaScSi2O6 host. The as-obtained NaScSi2O6:Eu2+ phosphor shows greenish yellow emission with the broad-band peak at 533 nm, and efficient energy transfer (ET) takes place between Eu2+ and Mn2+ in NaScSi2O6, leading to a series of color-tunable phosphors emitting at 533 and 654 nm for the designed NaScSi2O6:Eu2+,Mn2+ phosphors under excitation at 365 nm. The ET mechanism of Eu2+ and Mn2+ has also been evaluated. We have demonstrated that NaScSi2O6:Eu2+ and NaScSi2O6:Eu2+,Mn2+ materials exhibit great potential to act as the effective phosphors for UV-LEDs.

Correction for ‘Structure and luminescence properties of green-emitting NaBaScSi2O7:Eu2+ phosphors for near-UV-pumped light emitting diodes’ by Chengying Liu et al., J. Mater. Chem. C, 2013, 1, 7139–7147.

We present a combined structural analysis on the powder of the Ca2Al3O6F phase using X-ray diffraction (XRD) and Raman spectroscopy techniques. The crystal structure of Ca2Al3O6F has been refined in the rhombohedral system, R space group, a = 17.3237(7) Å, c = 7.00017(4) Å, V = 1819.38(2) Å3, Z = 6. The Ca2Al3O6F phase consists of almost ideal AlO4 tetrahedrons linked through corners, Ca2+ ions in voids, and F− ions disordered over 6 sites around the Ca2 ion. The two different Ca sites have also been verified by the photoluminescence spectrum and decay curves using Eu2+ as the probe ion substituted onto the Ca2+ sites. A lattice dynamics simulation based on the simplified version of the Born–Karman potential model has been produced. Calculated Raman phonon modes agree qualitatively well with the experimental data. The calculations show that the strong line at 538 cm−1 (Ag) corresponds to the vibrational mode of a six-membered AlO4 tetrahedrons ring, and the line at 572 cm−1 (Ag) corresponds to the full symmetric vibration of fluorine atoms in the ab crystal plane.

The substituted activator ions Eu2+ in the β-Ca3(PO4)2-type structure, Ca9NaMg(PO4)7 compound, have been studied as emission centers, as well as structural probes. The crystal structure and crystallographic sites of Eu2+ in Ca9NaMg(PO4)7 have been identified by Rietveld refinements, electron paramagnetic resonance (EPR) spectroscopy analysis and combined photoluminescence spectral analysis, respectively. Ca9NaMg(PO4)7:Eu2+ phosphor exhibits a broad emission band in the visible light region with three distinguished peaks centered at 415, 458, and 615 nm, which are ascribed to different Eu2+ emission centers occupied in three different Ca crystallographic sites. The concentration quenching behavior, variation in lifetimes and the temperature dependent luminescence properties have been investigated as a function of different emission centers, 415, 458, and 625 nm for Ca9NaMg(PO4)7:Eu2+ phosphor. Accordingly, the relationship among three different Eu2+ luminescence centers originating from three different Ca2+ crystallographic sites has been found and verified.

Ce3+ and Ce3+/Tb3+-activated Y4Si2O7N2 phosphors are synthesized by the solid-state method, which can be efficiently excited by near ultraviolet (UV) light emitting diode (LED) chips. The PL spectrum of Y4Si2O7N2:Ce3+ shows a broad hump between 380 and 650 nm, assigned to the electron transition from the 4f energy level to different 5d sub levels of the Ce3+ ions at different Y3+ sites. The color of the Y4Si2O7N2:Ce3+ phosphor can shift from blue to green by introducing Tb3+. In addition, the energy transfer process from Ce3+ to Tb3+ in the Y4Si2O7N2 host was investigated and discussed in terms of both the luminescence spectra and decay curves. The energy transfer critical distance has been calculated and evaluated by the concentration quenching method. Therefore, the Ce3+ and Ce3+/Tb3+-activated Y4Si2O7N2 phosphors can serve as key materials for phosphor-converted white-light UV-LEDs.

A series of iso-structural green-emitting Na3(Y,Sc)Si3O9:Eu2+ phosphors with different Y/Sc ratios have been synthesized by a solid-state reaction. All of the phosphors exhibited strong broad absorption bands in the near ultraviolet (n-UV) range, and gave bright green emission upon 365 nm excitation light. As for the composition-optimized Na3Y0.3Sc0.7Si3O9:Eu2+ phosphor, the critical Eu2+ quenching concentration (QC) was determined to be about 3 mol%, and the corresponding QC mechanism was verified to be the dipole–quadrupole interaction. The fluorescence decay curves, temperature dependence photoluminescence and CIE value of Na3Y0.3Sc0.7Si3O9:Eu2+ phosphors were discussed. A white light-emitting diode (LED) lamp was fabricated based on the green-emitting Na3Y0.3Sc0.7Si3O9:Eu2+ phosphor and combining a 370 nm n-UV chip and the commercial blue-emitting BaMgAl10O17:Eu2+ and red-emitting CaAlSiN3:Eu2+ phosphors. The produced white-light n-UV LED lamp gave CIE chromaticity coordinates of (0.3690, 0.3782), a high color rendering index of 85.6 and a warm color temperature of 2300 K.

Green-emitting phosphor Eu2+ doped NaBaScSi2O7 was synthesized by a solid-state reaction, and the photoluminescence properties were investigated in conjunction with a structural analysis. The crystallographic occupancy of Eu2+ in the Sc silicate NaBaScSi2O7 matrix was studied based on the Rietveld refinements results and the crystal chemistry rules. The optimum concentration of Eu2+ in the NaBaScSi2O7 phosphor was about 10 mol%, and the concentration quenching mechanism was verified to be the dipole–dipole interaction. Upon excitation at 365 nm, the composition-optimized NaBaScSi2O7:Eu2+ exhibited strong green light peaking at 501 nm with the CIE chromaticity (0.0706, 0.5540) and a high internal quantum efficiency of about 65%. The thermally stable luminescence properties were also studied and compared with those of the commercial green phosphors. A white light emitting diode (w-LED) lamp was finally fabricated by using the present green phosphor and the commercial blue and red phosphors, which exhibited a high color rendering index (Ra) of 86.5 at a correlated color temperature of 2528 K with CIE coordinates of x = 0.353, y = 0.324. These results suggest that NaBaScSi2O7:Eu2+ is a potential green phosphor candidate for near-UV-pumped w-LEDs.