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Ce 3+ , Tb 3+ co-doped T-phase orthosilicate Ba 1.2 Ca 0.8 SiO 4 phosphors were prepared by means of solid state reactions. The synthesized samples were investigated using XRD and PL emission and excitation spectra. The emission spectra for Ce 3+ doped Ba 1.2 Ca 0.8 SiO 4 phosphors show broad bands in the 320–550 nm spectral region. The excitation spectra exhibit several absorption peaks in the range of 250–400 nm. Both the emission and excitation spectra are dependent on the excitation or monitoring wavelengths. We attribute these results to Ce 3+ ions occupying two different crystallographic sites (i.e., Ce I and Ce II). The Ce 3+ , Tb 3+ co-doped Ba 1.2 Ca 0.8 SiO 4 phosphors show Tb 3+ -related line emissions in the 475–600 nm spectral region and Ce 3+ -related band emissions in the 350–525 nm spectral region when the 4 f → 5d transition of Ce 3+ is excited (λ ex  = 345 nm), indicating that energy transfer from Ce 3+ to Tb 3+ takes place. Moreover, the emission intensity of 5 D 4 → 7 F 5 transition for Ba 1.00 Ce 0.02 Tb 0.08 Li 0.10 Ca 0.8 SiO 4 is 30 times stronger than that of Ba 1.04 Tb 0.08 Li 0.08 Ca 0.8 SiO 4 sample under 345-nm UV excitation. [ABSTRACT FROM AUTHOR]

The Eu 2+ , Ce 3+ , Tb 3+ and Ce 3+ -Tb 3+ doped ternary metal diphosphate K 2 Ba 3 (P 2 O 7 ) 2 is prepared using high temperature solid state synthesis. K 2 Ba 3 (P 2 O 7 ) 2 :Eu 2+ shows a deep blue emission ( λ max = 405 nm) when it is excited by UV lights. The broad peak at 405 nm can be decomposed to two Gaussian curves with maxima at 405 and 440 nm which can be attributed to the presence of two crystallographically different Eu 2+ sites in the crystal structure. The emission spectrum of K 2 Ba 3 (P 2 O 7 ) 2 :Ce 3+ is dependent of the excitation wavelength that also results from the two crystallographically different Ce 3+ sites. The emission spectrum of K 2 Ba 3 (P 2 O 7 ) 2 :Tb 3+ shows the 5 D 3 and 5 D 4 emission lines. The f-d spin-allowed and spin-forbidden transitions in Tb 3+ in K 2 Ba 3 (P 2 O 7 ) 2 are at about 225 and 250 nm, respectively. For the (Ce 3+ , Tb 3+ ) co-doped K 2 Ba 3 (P 2 O 7 ) 2 system, the energy transfer from Ce 3+ to Tb 3+ is observed. [ABSTRACT FROM AUTHOR]

Abstract: Sn2+- and Sn2+/Mn2+-doped α-Sr2P2O7 phosphors have been synthesized by using the traditional solid-state reaction. The photoluminescence of Sn2+ and Sn2+/Mn2+ in α-Sr2P2O7 are reported and discussed. The Sn2+-activated material exhibits a blue-emitting band peaking at about 450nm under UV excitation. The Mn2+ emission peaking at about 565nm of Sn2+/Mn2+ co-doped samples can be enhanced through energy transfer from Sn2+ to Mn2+. Combining emission colors of Sn2+ and Mn2+ under UV excitation, white light emission can be achieved. [Copyright &y& Elsevier]

Abstract: Novel Eu3+ doped zirconate garnet-type ceramics, Li7(La3−x Eu x )Zr2O12 with x=0, 0.001–1.0, have been synthesized by solid state reaction and the purity phase of the samples was checked by XRD. Room temperature steady and time-resolved emission spectra, under UV and visible light excitation energy, have been investigated. The concentration effect on the quenching blue emission, due to the Zr–O charge transfer transition and 5D0→7F2 emission transition of Eu3+ were studied in detail. The results indicate that there exists efficient energy transfer from host to Eu3+. The mechanism of interaction between Eu3+ ions has also been investigated by means of the Inokuti–Hirayama model. [Copyright &y& Elsevier]

Abstract: A blue-emitting phosphor Sr3P4O13:Eu2+ was synthesized by a solid state reaction. The luminescence properties of Sr3P4O13:Eu2+ phosphors as well as their thermal quenching and the luminescence decay behavior were firstly investigated in detail. The emission spectrum is an asymmetric band at room temperature, while it exhibits two distinct bands when the temperature falls to 20K. With increase temperature, the two bands become difficult to distinguish and the emission intensity decreases. The peak of emission bands shifts towards shorter wavelengths as temperature increases. The decay curves are nearly exponential for 390nm emission; while those for 450nm emission are exponential only when the temperature is lower than 230K. The lifetime is temperature independent when the temperature is lower than 200K. The lifetime decreases as the temperature increases. Sr3P4O13:Eu2+ is a potential blue-emitting near-UV convertible phosphor. [Copyright &y& Elsevier]

Abstract: Tb3+ ions activated Li4SrCa(SiO4)2 phosphors were synthesized using a solid state reaction method. The phase impurity was checked by XRD. The photoluminescence (PL) excitation spectrum, emission spectra at room and high temperature, decay curves of samples with different Tb3+ ions concentration were studied in detail. Cross-relaxation and the Inokuti–Hirayama model were used to analyze the experimental results. Li4SrCa(SiO4)2:xTb3+ are thermally stable and color tunable phosphors. [Copyright &y& Elsevier]

Abstract: (Gd1−x Eu x )(BO2)3 (0≤x≤1) phosphors are synthesized by traditional high temperature solid state reaction. The photoluminescence (PL) properties of Gd(BO2)3 and Gd(BO2)3 activated with Eu3+ are investigated. The PL spectra exhibit the typical characteristic emission and excitation of Gd3+ and Eu3+ ions, and support the energy transfer taking place from Gd3+ to Eu3+ ions. The relationship between Eu3+ doping concentration and emission intensity is also studied. Even if all of the Gd3+ ions are substituted by Eu3+ ions, the concentration quenching between Eu3+ happens. However, the quenching is not complete. The luminescence decay curves are measured, and the lifetimes become short with the Eu3+ content increasing. The decreasing Gd3+ lifetimes also indicates that there exists efficient energy transfer between Gd3+ and Eu3+ ions. [Copyright &y& Elsevier]

Abstract: Sr2Mg(BO3)2:Ce3+,Li+ and Sr2Mg(BO3)2:Ce3+,Li+,Mn2+ phosphors have been synthesized by conventional solid state reaction technology at 900°C for 12h in reducing atmosphere. The phase purity, photoluminescence (PL) properties, thermal stability, energy transfer and luminescent decay curves have been investigated. Sr2Mg(BO3)2:Ce3+,Li+,Mn2+ phosphors show blue and deep-red [1] For interpretation of color in Figs. 1–6, the reader is referred to the web version of this article. 1 emission bands. The deep-red emission band is attributed to the energy transfer from Ce3+ to Mn2+. The fluorescence lifetimes of Ce3+ in co-doped sample are shorter than that in single doped one, which confirms that the energy transfer takes place. The phosphors have weak thermal quenching. The luminescence properties of Sr2Mg(BO3)2:Ce3+,Li+,Mn2+ make the phosphor a new bicolor emitting material. [Copyright &y& Elsevier]

Abstract: Luminescence properties of the Sm3+, Dy3+ doped LaMoBO6 phosphors are reported. LaMoBO6:Sm3+ exhibits orange emission corresponding to the 4G5/2 → 6H7/2 transition. LaMoBO6:Dy3+ exhibits two emission bands. The yellow band (570nm) corresponds to the 4F9/2 → 6H13/2 transition, and the blue one (482nm) corresponds to the 4F9/2 → 6H15/2 transition. The optimum concentration of Sm3+ and Dy3+, the critical distance of the concentration quenching, and the decay curves have also been investigated. The analysis of the decay curves indicates that cross-relaxation is primarily responsible for the concentration quenching. [ABSTRACT FROM AUTHOR]

Abstract: Sr2LiSiO4F co-doped with Ce3+, Mn2+ have been synthesized by means of solid state reactions. Their photoluminescence (PL) emission spectra, excitation spectra and the decay profiles of Ce3+ emission have been measured at room temperature. The emission peak around 410nm is ascribed to the 5d1 to 2F5/2 and 2F7/2 transitions of Ce3+ ions, while the peak around 680nm is ascribed to the 4T1–6A1 transition of Mn2+ ions. The decay rate of the 5d state within Ce3+ ion under 355nm laser excitation becomes faster with the increase of Mn2+ concentration. The analysis of the observed spectra confirms that there exists energy transfer from Ce3+ to Mn2+. [Copyright &y& Elsevier]

Abstract: Orange-emissive Ce3+/Eu2+ co-doped Sr3Al2O5Cl2 phosphors were synthesized by a solid-state reaction. The large overlap between the emission spectrum of blue Sr3Al2O5Cl2:Ce3+ and the excitation spectrum of orange Sr3Al2O5Cl2:Eu2+, and the shortening trend in lifetime of Ce3+ donors with increasing Eu2+ concentration in Sr3Al2O5Cl2:Ce3+, Eu2+ provide the strong evidence of energy transfer from Ce3+ to Eu2+ ions. It supports that the orange emission intensity of the optimal co-doped phosphor is 1.5 times stronger than that of single Eu2+-doped one. The Sr3Al2O5Cl2:Ce3+, Eu2+ phosphor is a promising orange-emitting phosphor for warm-white-light-emitting diode because of its effective excitation in the near ultraviolet range. [Copyright &y& Elsevier]

Abstract: Orange-emitting Sr3Al2O5Cl2:Eu2+ phosphors were synthesized by a high-temperature solid-state reaction. The excitation spectrum shows a broad band from the UV region to the blue region. The emission spectrum shows strong orange emission peaking at 610 nm, attributed to the d–f transition of the Eu2+ ion. By combining the Sr3Al2O5Cl2:Eu2+ phosphor with 420 nm and 460 nm chips, three white light-emitting diodes (LEDs) were fabricated. The warm-white LEDs show color rendering indexes of 76, 66 and 90 with color temperatures of 2447, 3546 and 4300 K, respectively. This new phosphor exhibits the potential to act as a single host doped with Eu2+ phosphor for UV or blue chip excited white LEDs. [Copyright &y& Elsevier]

Abstract: This paper reports the photoluminescence (PL) properties of Tb3+ in NaBa4(BO3)3, as well as the time-resolved luminescence properties. The PL excitation spectrum exhibits intense f→f transition absorption; the PL emission spectrum shows the strongest 5D4 → 7F5 emission at 540nm. The relative intensity of 5D3 emission is much weaker than that of 5D4 emission even in the samples with lower Tb3+ concentration. The 5D3 → 5D4 cross-relaxation produces a marked increase in the 5D3 decay rate with increasing Tb3+ concentrations and introduces a non-exponential component into the initial part of the decay. The dipole–dipole interaction is found to be responsible for the cross-relaxation. The decay curves of 5D4 → 7F5 transition exhibit an initial rise phenomenon. The two exponential fitting indicates that the initial slow rise is attributed to the 5D3 → 5D4 cross-relaxation process. [Copyright &y& Elsevier]

Abstract: Novel Eu3+, Ce3+ activated NaBa4(BO3)3 phosphors were synthesized by solid-state reactions. The excitation spectrum of NaBa4(BO3)3:Ce3+ consists of an intense band peaking at 350nm and a weak band in the higher energy side, and the emission spectrum exhibits a blue band with a maximum at about 420nm. The Eu3+ emission in NaBa4(BO3)3 consists of the transitions from 5 D 0 to 7 F J , and the excitation spectrum consists of broad excitation band peaking at 270nm and some intense narrow lines. The optimum doped concentration, the critical distance of the concentration quenching, and the fluorescence lifetime have also been investigated. [ABSTRACT FROM AUTHOR]

Abstract: A novel blue-emitting Sr3Al2O5Cl2:Ce3+,Li+ phosphor has been synthesized by solid state reaction. The excitation spectrum shows a broad band extending from 300 to 400 nm, and the emission spectrum shows a broad blue band peaking at 450 nm with a half width of about 100 nm. The emission intensity at 250 °C remains at about 50% of that at room temperature. The decay curve at the emission peak consists of fast and slow components. The Sr3Al2O5Cl2:Ce3+,Li+ should be a promising blue phosphor for near ultraviolet-based white-light-emitting diodes. [Copyright &y& Elsevier]