The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.201901517. Perovskite Light-Emitting DiodesPerovskite light-emitting diodes (PeLEDs) are gaining considerable attention for applications in next-generation displays and lighting due to the favorable features of PeLEDs such as high photoluminescence quantum-yield, broadly tunable bandgaps, high color purity, and facile solution processability. [1][2][3][4][5] In recent years, rapid progress has been made in improving the efficiency of PeLEDs as a result of the tremendous efforts devoted to organic-inorganic hybrid and all inorganic perovskite materials. [6][7][8][9][10] To date, the highest external quantum efficiencies (EQE) of green-and red-emitting PeLEDs have reached

Lanthanide (Ln 3+ ) doped Gd 2 O 3 nanoparticles (NPs) have been prepared via a thermal treatment of gadolinium carbonate precursor, which was obtained by simple hydrothermal treatment of Gd(NO 3 ) 3 solution in the presence of urea and glycerol. The size of the nanoparticles could be fine tuned from 270 to 10 nm by varying the amount of glycerol, which acted as a chelating agent to control the size of the nanoparticles. Calcination of the gadolinium carbonate nanoparticles at 500 C led to the formation of uniform Gd 2 O 3 nanoparticles without any obvious morphology change. By doping the lanthanide ions (Yb, Er/Tm) into the Gd 2 O 3 host matrix, these nanoparticles emitted strong upconversion (UC) fluorescence under 980 nm near infrared (NIR) excitation. Moreover, their emission colors could be tuned by simply changing either the co-dopant concentration or the dopant species. Water dispersibility was achieved by forming a silica layer on the surface of the Gd 2 O 3 nanoparticles. The possibility of using these silica-coated upconversion nanoparticles for optical imaging in vitro/in vivo has been demonstrated. It was also shown that these Gd 2 O 3 nanoparticles brightened the T 1 -weighted images and enhanced r 1 relaxivity of water protons, which suggested they act as T 1 contrast agents for magnetic resonance (MR) imaging. Thus, Gd 2 O 3 nanoparticles doped with Ln 3+ ions provide the dual modality of optical and magnetic resonance imaging.

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Here, we describe the fast and mass fabrication of monazite lanthanum orthophosphate (LaPO 4 ) nanoparticles via a simple sol-gel method under the assistance of microwave irradiation. The procedure involves formation of homogeneous, transparent, metal-citrate-EDTA gel precursors using both citric acid (CA) and ethylenediamine tetraacetic acid (EDTA) as the complexing agent followed by microwave irradiation, which promotes prompt thermal decomposition of the metal-citrate-EDTA gel precursors to yield the final nanoparticles. Thermogravimetric/differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the as-synthesized nanoparticles. About 23 g of single monoclinic phase, approximately 100 nm diameter, LaPO 4 spherical nanoparticles were readily obtained at 800 °C within 0.5 h, and the nanospheres were themselves composed of Ultrafine nanocrystals of a few nanometers in diameter. Furthermore, photoluminescence (PL) characterization of the Li + -and Eu 3+codoped LaPO 4 nanocrystals was carried out. The effects of microwave irradiation temperature and Eu 3+ active center concentration, especially the doping concentration of Li + on the PL properties, were elaborated in detail. Room-temperature photoluminescence (PL) characterization revealed that the optical brightness as well as the intensity ratio of 5 D 0 -7 F 1 to 5 D 0 -7 F 2 is highly dependent on the Li + ions concentration. Introduction of 5 mol % Li + into the crystal structure enhanced the PL emission brightness more than 2-fold, and the Li 0.05 Eu 0.05 La 0.9 PO 4 nanophosphor showed the relatively most promising PL performance with the most intense emission.

Adsorption irreversibility of Zn(II) on TiO 2 at various temperatures was studied using a combination of classical macroscopic methods and extended X-ray absorption fine structure (EXAFS) spectroscopy. When the temperature was increased from 5 to 40 • C, the Zn(II) adsorption capacity increased by 130%, and adsorbed Zn(II) became more reversible. The standard Gibbs free energy change ( G 0 ) of the adsorption reaction at 5, 20, and 40 • C was determined to be −19.58 ± 0.30, −22.28 ± 0.10, and −25.14 ± 0.21 kJ mol −1 , respectively. And the standard enthalpy ( H 0 ) and entropy ( S 0 ) were 24.55 ± 2.91 kJ mol −1 and 159.13 ± 0.53 J mol −1 K −1 , respectively. EXAFS spectra results showed that the hydrated Zn(II) was adsorbed through fourfold coordination with an average Zn-O bond distance of 1.98 ± 0.01 Å. Two Zn-Ti atomic distances of 3.25 ± 0.02 and 3.69 ± 0.03 Å were observed, which corresponded to an edge-sharing linkage mode (strong adsorption) and a cornersharing linkage mode (weak adsorption), respectively. As the temperature increased from 5 to 40 • C, the number of strong adsorption sites (N 1 ) remained relatively constant while the number for the weak adsorption sites (N 2 ) increased by 31%. These results indicate that the net gain in adsorption capacity and the decreased adsorption irreversibility at elevated temperatures were due to the increase in available weak adsorption sites (N 2 ) or the decrease in the ratio of N 1 /N 2 . Both the macroscopic sorption/desorption equilibrium data and the molecular level evidence of this study suggest that in a given environmental system (e.g., soils or natural waters) zinc and other similar heavy metals are likely more mobile at higher temperatures.

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