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Novel Te4+-doped CaYAlO 4 phosphors were obtained by a solid-state reaction. Te4+-doped CaYAlO 4 samples had a tetragonal crystal structure and emit deep-red light at 715 nm excited by 325 nm, which was ascribed to Te4+ luminescence center. The luminescent intensity of CaYAlO 4 : Te4+ samples increased with the sintering temperature increasing, reaching a maximum at 1500 °C, then began to drop. The optimal Te4+ doping concentration was 2 mol%. Lifetime of CaYAlO 4 : 2%Te4+ phosphors was 1.54 ms. The luminescent intensity of CaYAlO 4 : 2%Te4+ phosphors decreased with the increase of test temperature and reached to 35.0% of the initial value at 425 K. The CaYAlO 4 : Te4+ phosphors have potential applications in bio-imaging, temperature sensor, solid-state lighting and solar cells etc. [Display omitted] • Te4+-doped CaYAlO 4 phosphors were synthesized by a solid-state method. • Te4+-doped CaYAlO 4 phosphors can emit efficient deep-red light at 715 nm excited by 325 nm. • Te4+-doped CaYAlO 4 phosphors had long lifetime of 1.54 ms. [ABSTRACT FROM AUTHOR]

Red phosphors with good thermal stability, high color temperature and color purity are critical in high power warm white LED devices. Herein, a series of single and co-doped Tb3+,Eu3+ polychromatic phosphors with pyrochlore structure based on Gd 2 Zr 2 O 7 have been prepared for the first time by a conventional solid phase reaction method. Compared to single doped Eu3+ phosphors, Tb3+,Eu3+ co-doped phosphors possess following advantages: improved UV absorption, increased photoluminescence intensity, extended luminescence range and improved thermal stability. At room temperature, the Gd 2 Zr 2 O 7 :Tb3+,Eu3+ phosphors exhibited a gradual shift from yellow-green emission at 544 nm to orange-red emission at 613 nm with increasing doping of Eu3+ ions. Energy transfer efficiency has been evaluated to be 71% by analyzing the fluorescence lifetime of Tb3+ ions. The concentration quenching mechanism under different conditions was analyzed in detail and it was concluded that the quenching of Tb3+ is caused by dipole-dipole interaction. In addition, the activation energy (ΔE a) of the Gd 1.92 Zr 2 O 7 :0.03Tb3+,0.05Eu3+ phosphor was calculated to be as high as 0.2674 eV compared to other Tb3+, Eu3+ co-doped phosphors, demonstrating its high thermal stability. WLEDs devices based on Gd 1.92 Zr 2 O 7 :0.03Tb3+,0.05Eu3+ phosphors have been prepared, which have low correlated color temperature (CCT) (5283 K), high color rendering index Ra = 85.5 K) and CIE coordinates chromaticity coordinate (0.3371,0.3333). All of the results show that Gd 2 Zr 2 O 7 :Tb3+,Eu3+ phosphors provide a new avenue to develop high quality red emission and high thermal stability phosphors for WLEDs. • doping with rare earth ions can effectively change the band gap energy and structural of Gd 2 Zr 2 O 7 phosphor. • achieving high energy transfer from Tb3+ to Eu3+ in Gd 2 Zr 2 O 7 phosphor. • Tb3+, Eu3+ co-doped Gd 2 Zr 2 O 7 phosphor with high thermal stability. • The LED devices assembled from Gd 2 Zr 2 O 7 :Tb3+,Eu3+ have excellent chromaticity coordinate stability, high CRI and low CCT. [ABSTRACT FROM AUTHOR]

Sm3+ and Sm3+/Eu3+ doped Li 6 Gd(BO 3) 3 (LGBO) powders were prepared by solid-state reaction. The microstructure, luminescent characteristics, energy transfer and fluorescence lifetimes were studied. Gd3+ can absorb energy and transfer it to Sm3+ under 278 nm excitation, which increases the luminescent intensity of Sm3+ at 567, 611 and 649 nm. Under 405 nm excitation, the 4G 5/2 -6H 5/2 transition belonging to Sm3+ and the 5D 0 -7F 2 transition belonging to Eu3+ appear in the emission spectra of Sm3+/Eu3+ co-doped LGBO phosphors, glowing yellow-orange and red light, respectively. The mechanism behind the energy transfer was analyzed, and the energy transfer efficiency was calculated to be 31.2% when the Sm3+ concentration reached 4mol%. The LGBO:Sm3+/Eu3+ phosphors have prospective applications in solid-state lighting, display devices, bio-imaging, etc. • The obtained Li 6 Gd(BO 3) 3 :Sm3+/Eu3+ phosphor has excellent luminescent properties. • Sm3+ acts as a sensitizer which extends the excitation range of Eu3+ in the near-uv and enhances Eu3+ emission. • The Li 6 Gd(BO 3) 3 :Sm3+/Eu3+ phosphor can emits a stronger orange-red light due to the energy transfer of Sm3+ to Eu3+. • The energy transfer efficiency from Sm3+ to Eu3+ can reach 31.2%. [ABSTRACT FROM AUTHOR]

A one-step microwave irradiation method was used to deposit carbon and nitrogen co-doped TiO 2 ((C, N)-TiO 2 ) on commercial brick ((C, N)-TiO 2 /brick). The as-prepared samples were characterized by X-ray diffraction, ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM). A selective technique was also used to investigate the concentration of hydroxyl radicals during UV–vis irradiation of the Methyl Orange solution with the as-prepared samples. The C and N dopants enhanced visible light absorption and provided a longer lifetime for the photo-generated electron–hole pairs. The SEM images showed that the as-prepared sample is porous. The dark adsorption and photodegradation test for (C, N)-TiO 2 /brick showed good photodegradation and good recyclability. The best photodegradation rate was 94% after 2 hr. The maximum degradation rate was maintained even after the 6th cycle. The good photocatalytic properties are attributed to the enhanced visible light absorption, enhanced pollutant adsorption arising from the porous structure of the (C, N)-TiO 2 thin film, and longer lifetime of the photo-generated electron–hole pairs. (C, N)-TiO 2 /brick should have potential commercial applications in photodegradation processes because of its low cost, good photodegradation, and excellent recyclability. [ABSTRACT FROM AUTHOR]

Ce3+/ Gd3+ co-doped NaBaBO 3 blue luminescent materials were synthesized by the solid-state reaction. Research shows that Ba2+ ions with larger ionic radius are replaced by Gd3+ ions and Ce3+ ions with smaller ionic radii. Gd3+ can act as a sensitizer to absorb energy and promote the luminescence of Ce3+.Under the excitation of 360 nm near ultraviolet light and X-ray, NaBaBO 3 :0.03Gd3+, 0.01Ce3+ can emit bright blue light, and its emission peak is located at 430 nm. [Display omitted] Ce3+ and Gd3+ co-doped NaBaBO 3 blue luminescent materials were synthesized by the solid-state reaction. X-ray diffraction, X-ray photoelectron spectrometer, and fluorescence spectrometer were used to analyze the crystal structure, the surface morphology, and the luminous properties. Ce3+/Gd3+ co-doped NaBaBO 3 phosphors can absorb near-ultraviolet light and emit bright blue light centered at 430 nm, which originates from the 5d-4f transition of Ce3+ ion. When the doping concentration of Ce3+ and Gd3+ was 1 % and 3 % respectively, Ce3+/Gd3+doped NaBaBO 3 had the strongest luminous intensity with a short decay time of about 23 ns. The addition of Gd3+ increases the luminescence intensity of Ce3+ doped NaBaBO 3. The CIE color coordinates are (0.1564, 0.0909). Ce3+/Gd3+ co-doped NaBaBO 3 powders are promising materials for WLEDs and scintillators. [ABSTRACT FROM AUTHOR]

Te4+-doped YCa 4 O(BO 3) 3 phosphors were successfully prepared by a high temperature solid-state reaction method. XRD, SEM and XPS were used to characterize the crystal structure, particle size, morphology and element valence state of the samples. The room temperature fluorescence properties of the phosphors were measured by a fluorescence spectrophotometer. The excitation and emission bands, peaked at 310 nm and 380 nm, correspond to the 1S 0 →3P 1 and 3P 0,1 → 1S 0 transitions of Te4+ ions, respectively. The 3 mol% Te4+-doped YCa 4 O(BO 3) 3 phosphor has the strongest fluorescence with a lifetime of 2.28 and 22.66 μs. The thermal quenching occurs at higher temperature, indicating a non-radiation transition that is dominated by the crossover process. The emission intensity of Te4+-doped YCa 4 O(BO 3) 3 phosphors at 380 nm changes linearly with the increase of temperature, suggesting that these fluorescent materials may be applied for temperature sensing. • A novel phosphor was prepared by solid-state reaction method. • Te4+-doped YCa 4 O(BO 3) 3 phosphors can emit efficient Near-UV light at 380 nm excited by 310 nm. • The physical mechanism of Te4+ ion luminescence versus doping concentration and temperature was investigated in detail. [ABSTRACT FROM AUTHOR]

Te4+ doped YAl 3 (BO 3) 4 phosphors prepared by high temperature solid-state reaction show a blue wide band located at 480 nm ranging from 400 to 600 nm under the 244 nm excitation. With the increase of Te4+ doping content, luminescence intensity first increases and then decreases. 3%Te4+ doped YAl 3 (BO 3) 4 phosphors prepared at 1200 °C have excellent luminescence with a lifetime of 7.18 μs. The chromaticity coordinates are in the blue region and range from (0.1966, 0.2862) to (0.2497, 0.3192). Te doped YAB can be a potential blue-light material. [Display omitted] Novel blue-emitting Te4+ doped YAl 3 (BO 3) 4 phosphors were obtained by high temperature solid-state reaction. XRD, SEM, XPS and PL were used to study the properties of Te4+ doped phosphors. YAl 3 (BO 3) 4 became the main phase at 1200 °C according to XRD results. The Te4+ doped YAl 3 (BO 3) 4 phosphors show a blue wide band at 480 nm, and 3%Te4+ doping in YAl 3 (BO 3) 4 phosphors synthesized at 1200 °C have the optimal luminescence with a lifetime of 7.18 μs. Te4+ doped YAl 3 (BO 3) 4 phosphors are a promising material for blue phosphors in LED, blue diode laser, plant growth, etc. [ABSTRACT FROM AUTHOR]