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A series of novel Eu3+-activated tellurate Ca (3-2x) Eu x Na x TeO 6 (x = 0.01–0.25) red-emitting phosphors were synthesized through a high-temperature solid-state route at 1220 °C. The phosphors were well crystallized in the space group P 2 1 /c (No. 14). Their photoluminescence emission and excitation spectra were investigated. The results indicate that the Ca 3 TeO 6 :Eu3+ phosphor can be effectively excited under 394 nm irradiation, which is suitable for UV LED chip. Upon 394 nm excitation, the Ca 3 TeO 6 :Eu3+ phosphor shows five peaks, corresponding to the 5D 0 –7F J (J = 0, 1, 2, 3 and 4) transitions of Eu3+. The optimal doping concentration of Eu3+ in Ca 3 TeO 6 : x Eu3+ was determined at 20 mol%. By temperature dependent emission spectra, the quenching temperature for Ca 3 TeO 6 :0.20Eu3+ was found to be over 500 K. The CIE chromaticity coordinates of Ca 3 TeO 6 :0.20Eu3+ are very close to the National Television System Committee (NTSC) standard red. [ABSTRACT FROM AUTHOR]

Single RE3+ (RE = Eu3+, Tb3+, Dy3+, Sm3+) doped Ba2Gd(BO3)2Cl phosphors were synthesized by the high temperature solid state reaction. Spectroscopic properties of Ba2Gd(BO3)2Cl: RE3+ under vacuum ultraviolet (VUV), ultraviolet (UV) light and low-voltage electron beam excitations were investigated. The Ba2Gd(BO3)2Cl: Dy3+ shows a white light emission under VUV, UV light and electron beam excitation, respectively. Upon different excited source excitation, Ba2Gd(BO3)2Cl: Tb3+ shows similar yellowish-green emissions. Ba2Gd(BO3)2Cl: Sm3+ and Ba2Gd(BO3)2Cl: Eu3+ phosphors show bright orange-red and red emitting under VUV, UV light and electron beam excitation. These results indicated that the Ba2Gd(BO3)2Cl: RE3+ phosphors can be considered as a bright multicolor phosphors for multifunctional application, such as Hg-free lamps, PDPs, W-LEDs and FEDs. [ABSTRACT FROM AUTHOR]

A series of novel silicate-based red-emitting K4Ca1−xSi3O9:xEu3+ (x = 0.01-0.30) phosphors were successfully synthesized via a high-temperature solid-state reaction method for the first time. The compounds were crystallized in the cubic structure with the space group Pa3¯. The photoluminescence spectrum of K4CaSi3O9:Eu3+ phosphor shows four peaks assigned to the 5D0-7FJ (J = 0, 1, 2, 3 and 4) transitions of Eu3+ upon 396 nm excitation. Judd-Ofelt intensity parameters and CIE were calculated from the photoluminescence data. The quenching temperature for K4CaSi3O9:0.30Eu3+ was estimated to be above 500 K. The superior thermal stability can be attributed to the rigid structure of the host. The good color saturation and high thermal stability indicate that K4CaSi3O9:Eu3+ phosphor is a potential candidate for light-emitting diodes. [ABSTRACT FROM AUTHOR]

Solar cells have been extensively studied as a means of green energy converters in recent decades, especially the silicon solar cells. However, the energy efficiency of crystalline solar cells is very low, which is due to the reason that they have a good absorption in 800–1100 nm region but a bad absorption in 300–500 nm region. Based on this, a series of Ce3+-Yb3+ codoped Ca 3 Al 2 O 6 samples are synthesized by the conventional solid state method in reduced atmosphere. Energy transfer process from Ce3+ to Yb3+ is affirmed by the characterizations of photoluminescence, photoluminescence excitation spectra and decay curves in different temperatures. The photoluminescence intensity and lifetime of Ce3+ decrease with the increase of Yb3+ content. And as the temperature increases, the energy transfer efficiency increases. These results demonstrated that the near-infrared luminescence from 2F 5/2 to 2F 7/2 transition of Yb3+ is implemented via a multi-phonon assisted energy transfer process in the Ce3+-Yb3+ ions pair. These phosphors exhibit broadband absorption in the ultraviolet region with efficient near-infrared emission (centering at 976 nm), which has better spectral response for crystalline Si solar cells. The obtained results illustrated that the phosphors have potential applications as spectral conversion materials to enhance the performance of crystalline Si solar cells. [Display omitted] • A novel near-infrared phosphor Ca 3 Al 2 O 6 :Ce3+, Yb3+ was synthesized. • The energy transfer from Ce3+ to Yb3+ is proved to be a multi-phonon assisted way. • The phosphor has better spectral response for crystalline Si solar cells. [ABSTRACT FROM AUTHOR]

Abstract A series of double perovskite Sr 2 MgTeO 6 :Sm3+/Dy3+ phosphors for solid-state lighting application were successfully synthesized by the solid-state reaction process. The phase structure, photoluminescence, thermal quenching, and decay behavior of the prepared phosphors were investigated. The photoluminescence of Sr 2 MgTeO 6 :Sm3+ exhibits red emission (640 nm) due to the transition from the 4G 5/2 → 6H 7/2 under 404 nm excitation. Sr 2 MgTeO 6 :Dy3+ exhibits two emission bands under 390 nm excitation. They are due to 4F 9/2 → 6H 15/2 (blue) and 4F 9/2 → 6H 13/2 (yellow) transitions of Dy3+, respectively. Sr 2 MgTeO 6 :0.10Sm3+ phosphor shows excellent thermal stability. Therefore, Sr 2 MgTeO 6 :Sm3+/Dy3+ phosphors are a promising candidate for UV chip-based WLED and solid-state lighting. [ABSTRACT FROM AUTHOR]

A series of Ca 3 TeO 6 : x Dy3+ (x = 0.01, 0.02, 0.05, 0.10, 0.15, 0.20, and 0.25) tellurate yellow-emitting phosphors were synthesized via the high-temperature solid-state method. The X-ray diffraction patterns of these phosphors revealed that all the samples have a double-perovskite type with monoclinic structure. The Ca 3 TeO 6 :Dy3+ phosphor exhibit characteristic emission transitions, 4F 9/2 –6H 15/2 transition and 4F 9/2 –6H 13/2 transition, respectively. The intense yellow light indicates that Dy3+ ion occupies the interstitial Ca site in the Ca 3 TeO 6 host. The optimal Dy3+ ion concentration was determined as 10 mol%. The critical energy transfer distance was calculated as 14 Å. The concentration quenching mechanism of Dy3+ was investigated in details. The temperature effect on photoluminescence was discussed in order to evaluate the thermal stability. The obtained results illustrate Ca 3 TeO 6 :Dy3+ was a new kind of yellow-emitting potential phosphor for WLEDs. A novel tellurate Ca 3 TeO 6 :Dy3+ phosphor with excellent thermal stability could be potential yellow-emitting candidate for WLEDs. Unlabelled Image • Novel yellow-emitting Ca 3 TeO 6 :Dy3+ tellurate phosphors were developed. • The temperature effect on photoluminescence was discussed. • The developed phosphor has great potential for UV LED. [ABSTRACT FROM AUTHOR]