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981.
Shuyao Cao Qian Chen Yangping Li Changying Wu Jie Xu Guanghua Cheng Feng Gao 《Journal of the European Ceramic Society》2021,41(9):4924-4933
Sm3+ doped KSr2Nb5O15 (KSN-Sm) textured ceramics with anisotropic photochromic and luminescence modulation behaviors provided a new strategy for the enhancement of anti-counterfeiting ability. The KSN-Sm textured ceramics were fabricated by the tape casting technology, which exhibited obvious grain-orientation, with Lotgering factor f(00l) of 0.62. The textured sample possessed evident difference of reflectivity, photochromic, luminescent and luminescence modulation properties among various grain-orientated directions. The difference of luminescent emission intensity was over than 30 % and the luminescence modulation ratios △Rt are 75.3 % and 63.3 % along paralleled and vertical [00l] orientations, respectively. These optical anisotropies were attributed to the different refractive indexes, distributions of photochromic centers and energy transfer rates at various orientations. This work is hopeful to achieve the multidirectional data recording and enhancement of anti-counterfeiting ability of photochromic ceramics by the anisotropic properties of textured ceramics. 相似文献
982.
《中国稀土学报(英文版)》2022,40(4):526-533
With narrow red photoluminescence (PL) bands, tetravalent Mn4+ doped phosphors show promising prospect in commercial application to effectively expand color gamut of phosphor converted LED displays. Here, we report a type of Sr2–zMg1+yYzAl22–xO36:xMn4+ phosphors with regular cage-like micro-spherical morphologies. The micron size spherical precursors were synthesized with a propylene oxide (PO) driven fast sol–gel method. The cage -like spherical morphology is beneficial to efficiently trapping much incident light to enhance the PL of the phosphors. Being calcined at 1300 °C, Sr2MgAl21.978O36:0.022Mn4+ only exhibits the internal quantum efficiency (IQE) of 24.91%. With the Mg2+-Mn4+ codoping and Y3+/Sr2+ substituting strategies, to fulfill charge balance and produce John-Teller distortion, IQE of Sr2–zMg1+yYzAl22–xO36:xMn4+ can be further improved up to 36.45%. The CIE color coordinates of Sr2–zMg1+yYzAl22–xO36:xMn4+ under near ultraviolet excitation can be stably fixed to (0.723, 0.227) at deep red region. It thus finds a potential application as pc-LED display with much broader color gamut than that of the NTSC standard. Therefore, Sr2–zMg1+yYzAl22–xO36:xMn4+ micron size spheres can be employed as promising red phosphors for high performance LED displays. 相似文献
983.
984.
The unsymmetrical and symmetrical azines prepared by condensation of benzophenone hydrazone with (di)aldehydes with thiophene rings were reported in this study The structures of obtained compounds were characterized by FTIR, 1H NMR, and 13C NMR spectroscopy as well as elemental analysis. Optical, electrochemical, and thermal properties of azines were investigated. The unsymmetrical azine with bithiophene unit exhibited liquid crystalline properties as was detected by DSC and POM experiments. All compounds are electrochemically active, however, only azines with bithiophene structure undergo reversible reduction process as was found in cyclic and differential pulse voltammetry (CV and DPV) studies. Additionally, the electronic properties, that is, orbital energies and resulting energy gap were calculated theoretically by density functional theory (DFT). The photovoltaic properties of two azines as active layer in organic solar cells at the configuration ITO/PEDOT:PSS/active layer/Al under an illumination of 1.3 mW/cm2 were studied. Active cell layers blends of poly 3-hekxylthiophene (P3HT) or poly 3-butylthiophene (P3OT) with azines were applied. The device comprising P3HT with symmetrical azine containing bithiophene unit showed the highest value of power conversion efficiency (0.82%). To the best of our knowledge, the azines are very seldom considered as potential compounds in active layer in bulk heterojunction (BHJ) solar cells. 相似文献
985.
《Ceramics International》2017,43(18):16356-16361
Yellow emitting BaWO4:3% Sm3+ phosphor was synthesized by a low-temperature molten salt method in LiNO3-KNO3. The prepared powders were characterized by X-ray diffraction (XRD), optical absorption and photoluminescence (PL) techniques. The crystal structure and related parameters were analyzed in detail by Rietveld refinement. The Judd–Ofelt (J-O) theory, which is used to explain the yellow emission mechanism and examine its luminescence properties, was applied to analyze the oscillator strengths, branching ratios, radiative lifetimes and transition probabilities of the BaWO4:3%Sm3+ system. PL spectrum presented three prominent emission bands located at 562, 599 and 645 nm which are corresponding to the transitions from 4G5/2 to 6H5/2, 6H7/2 and 6H9/2, respectively. The CIE coordinates and correlated color temperature of the sample were also evaluated. 相似文献
986.
Nonlinear optical Bi2ZnOB2O6 single crystals doped with Pr3+ ions were grown using the Kyropoulos method. The absorption and luminescence properties of these new systems were investigated for the first time. The crystals are characterized by the large values of nonlinear optical coefficients. Effective luminescence of the Pr3+ ions makes this system an excellent candidate for the near-infrared (NIR) and/or ultraviolet (UV) to visible (VIS) laser converters. Based on the obtained experimental spectroscopic data, detailed analysis of the absorption and luminescence spectra was performed using the conventional Judd–Ofelt theory. Those transitions, which can be potentially used for laser applications of the Pr3+ ion, have been identified. In addition to the intensity parameters Ω2, Ω4, Ω6 the branching ratios and radiative lifetimes were estimated for all possible transitions in the studied spectral region. 相似文献
987.
9-[(5-nitropyridin-2-aminoethyl) iminiomethyl]-anthracene (NAMA) was synthesized for the first time from the reaction between 9-antracene carboxaldehyde and 2-(2-aminoethylamino)-5-nitropyridine under mild reaction conditions. The structure of the nitropyridine-conjugated anthracene (NAMA) was characterized using 1H-NMR, 13C-NMR and elemental analysis techniques. Furthermore, electroluminescent behavior of the NAMA was investigated by using a material based on polycyclic aromatic hydrocarbons (PAHs) in organic light-emitting diodes (OLEDs). It was observed that the NAMA exhibits blue/near UV emission at 410 nm with a high density signal. The optimized device structure, ITO/CuPc/α−NPD/NAMA/Alq3/LiF/Al is characterized by blue/near UV electroluminescence (EL) and a high current density with 7735 cd m−2 maximum brightness at approximately 10.4 V. The emitting color of the device showed the blue/near UV emission (x, y) = (0.14, 0.10) at 277.1 mA cm−2 in CIE (Commission Internationale de l’Eclairage) chromaticity coordinates with a long operational lifetime (180 h). 相似文献
988.
J.L. Gomes S.C.P. Rodrigues G.M. Sipahi L. Scolfaro E.F. da Silva Jr. 《Materials Science and Engineering: B》2012,177(12):962-966
We studied the spin-polarized charge densities in II–VI-based diluted magnetic superlattices formed of p-doped ZnTe:Mg/ZnTe:TM/ZnTe:Mg non-magnetic/magnetic/non-magnetic layers, with TM standing for transition metal. The calculations were performed within a self-consistent k.p method, in which are also taken into account the exchange correlation effects in the local density approximation. Our results show a limit for the width of the non-magnetic layer for which the difference between the opposite spin charge densities is maximized, indicating the best conditions to obtain full polarization by varying the TM content. We also discuss these effects in the calculated photoluminescence spectra. Our findings point to the possibility of engineering the spin-polarized charge distribution by varying the widths of the magnetic and non-magnetic layers and/or varying the TM concentration in the magnetic layers, thus providing a guide for future experiments. 相似文献
989.
The electronic structure of CaZr4(PO4)6 was calculated using the CASTEP code and the band gap for CaZr4(PO4)6 can reach up to 4.30 eV. Ca1−xEuxZr4(PO4)6 (0.01 ⩽ x ⩽ 1) samples were prepared by a high temperature solid-state reaction method. XRD analysis shows that Eu2+ ion can be totally incorporated into CaZr4(PO4)6 forming complete solid solutions with trigonal lattice. Ca1−xEuxZr4(PO4)6 (0.01 ⩽ x ⩽ 1) shows typical broad band emission in wavelength range from 400 to 650 nm for both under ultraviolet (UV) light and X-ray excitation, originating from the 4f65d1 → 4f75d0 transition of Eu2+ ions. With increasing Eu2+ concentration, there is abnormal blue-shift of the emission peaks for Ca1−xEuxZr4(PO4)6 due to the decreasing crystal field strength and Stokes shift. With increasing temperature in CaZr4(PO4)6: Eu2+, its emission bands show the anomalous blue-shift with decreasing intensity. The overall scintillation efficiency of Ca0.9Eu0.1Zr4(PO4)6 is 1.7 times of that of Bi4Ge3O12 (BGO) powder under the same conditions. In addition, its predominant decay time is about 50 ns at room temperature. The potential application of Eu2+-doped CaZr4(PO4)6 has been pointed out. 相似文献
990.
《Ceramics International》2022,48(9):12721-12728
Recent surge in additive manufacturing efforts demonstrate stereolithography as a promising technique for fabricating glass materials due to the high speed and scalability of the process. However, little efforts have been devoted to manufacture borosilicate glass by the stereolithographic process. One of the challenges is that its relatively low softening temperatures could interfere with the thermal post-printing process and introduce poor fidelity and structure instability. Here, we report on the first demonstration of stereolithographic manufacturing of cerium-doped (Ce-doped) (<10%) and undoped borosilicate glass which was enabled by a multi-step post thermal processing. The optical properties of the printed glass depend on thermal processing parameters (temperature, time, and environment) and can be readily tuned and optimized for a wide range of applications. The printed amorphous glass shows good structural stability with band gap of 3 eV, Urbach energy of 0.75 eV and refractive index of 2.14 for 8% Ce-doped glass, respectively. These results indicate Ce-doped glass fabricated by stereolithography is suitable for scintillator applications and that additive manufacturing could be promising for borosilicate glass fabrication. 相似文献