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As photocatalysts exhibit selectivity toward various pollutants, it is necessary to develop different and novel photocatalysts. In this work, a novel photocatalyst-nitrogen-doped simonkolleite Zn5(OH)8Cl2·H2O (DSM) is prepared through a new facile method: calcinating the mixture of zinc hydroxide, urea, and guanidine hydrochloride at 575 °C for 1 h in a furnace with an air atmosphere. The as-prepared sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectra, UV-visble near-infrared diffuse reflection spectra (UV-Vis-NIR DRS), Brunauer-Emmett-Teller (BET) method, Ramen spectra and Zeta potential measurement, photocatalytic properties, as well as active species trapping experiments. XRD and XPS show the as-prepared powder is nitrogen-doped simonkolleite Zn5(OH)8Cl2H2O (DSM) with a small ZnCl2 fraction. SEM investigation indicates that the as-prepared powder possesses a flower-like layered shape. The UV-Vis-NIR exhibits that after doping, the DSM possesses strong light absorption in the ranges of 300-500 and 1400-2500 nm, a direct electronic transition with a band gap energy of 2.469 eV. PL measurement reveals a strong photoluminescence and an up-conversion from lower to higher-energy visible light in as-prepared samples. Zeta potential investigations show that during photocatalysis, the charges on as-prepared photocatalyst are positive. The photocatalytic experiments show a good dark adsorption, a high photodegradation (99.4% at 60 min), a high pseudo-first-order constant (k) of 0.0261 min−1. Meanwhile, the active species trapping experiments suggest that hole (h+) is the dominant active species during photocatalysis. It is concluded that the doping favors in enhancing vis-light-photocatalysis. This work makes a significant contribution to the literature. [ABSTRACT FROM AUTHOR]

A series of La (3- x) Dy x BWO 9 phosphors and La (3- x) Dy x BWO 9 /PMMA composite films were prepared. The absorption and photoluminescence of phosphors as well as the transmittance and radioluminescence of the composite films were studied. La (3- x) Dy x BWO 9 phosphors mainly emit blue light at 486 nm and yellow light at 577 nm when excited at 310 nm, and the phosphors have good thermal stability. La (3- x) Dy x BWO 9 /PMMA composite films have good transmittance and X-ray radiation properties. The results indicate that La (3- x) Dy x BWO 9 phosphors can be used in solid-state lighting devices, and the prepared composite films are expected to be used in fields such as X-ray imaging and radiation detection. [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]

Luminescent transparent ceramics (Tb 1-x Y x) 3 Al 5 O 12 (x = 0, 0.2, 0.5, 0.8) are successfully prepared by a solid-state method with additional hot isostatic pressing (HIP) treatment, and the structure and properties are investigated by XRD, SEM, PL, UV–Vis spectrophotometry and ellipsometry. The Y-containing samples are shown to be solid solution phases between TAG and YAG. The PL intensity is 14 times stronger with the incorporation of 80 mol.% Y, and the 5D 4 →7F 5 emission lifetime of Tb3+ is prolonged from 0.357 to 3.035 ms at room temperature. A unique magnetoluminescence emerges upon the incorporation of Y, showing an interesting emission decrease to 55% as the Y content reaches 80 mol.%. Remarkably, this magnetoluminesence can occur at room temperature without an intense magnetic field. Based on our work, transparent (Tb 1-x Y x) 3 Al 5 O 12 ceramics exhibit the potential for applications in green emitters, optical instruments and photoelectric devices. In particular, the magnetoluminescence provides a simple, noncontact and nondestructive route for probing magnetic fields. [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]

Er3+ and Yb3+ codoped MoS 2 powders have been fabricated by hydrothermal synthesis. The impact of Er3+ and Yb3+ codoping on the structure, morphology, energy band structure and upconversion photoluminescence properties of samples have been studied by XRD, SEM, TEM, XPS and UPL. XRD results reveal that the crystal structure of samples is well matched with the 2H–MoS 2 , and the crystallinity of MoS 2 –Er:Yb significantly increases after annealing. The morphology of samples prepared by hydrothermal synthesis presents flower-like balls composed of nanosheets, while the annealed MoS 2 –Er:Yb samples are the triangular sheet. A small amount of Er3+ and Yb3+ ions doping has little effect on the band structure of MoS 2 but the number of carriers. The MoS 2 –Er:Yb powders show strong green emission at 528 nm, 549 nm and weak red emission at 662 nm under 800 nm and 980 nm laser light pumping, which stem from the Er3+ transition of (2H 11/2 , 4S 3/2)→4I 15/2 and 4F 9/2 → 4I 15/2. Therefore, the MoS 2 –Er:Yb powders can be a promising material in phosphors, biomedical imaging, dye-sensitized solar cells, etc. • Er3+ and Yb3+ codoped MoS 2 powders have prominent green upconversion photoluminescence. • Annealing can significantly improve the crystallinity and upconversion photoluminescence of MoS 2 –Er:Yb samples. • The introduction of Er3+ and Yb3+ ions effectively increases the number of carriers and decreases the impedance of MoS 2. [ABSTRACT FROM AUTHOR]