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991.
首先,使用高温熔融冷却技术,制备了不同掺入比例的NaF,YF_3玻璃样品。然后将退火后的玻璃样品切割加工成15mm×15mm×3mm,实施抛光处理。最后,通过差热分析确定玻璃转变温度Tg、第一析晶峰Tx和玻璃整体析晶峰Tc等特征温度。将样品在600℃下热处理2h后,在玻璃样品中成功的析出了不同晶粒尺寸的NaYF4微晶。对样品进行了XRD,TEM和EDX的分析,可以确定不同样品中晶粒的尺寸与分布。结合样品荧光光谱和吸收光谱的分析,探讨了Er~(3+)在不同晶粒尺寸样品中的上转换发光特征,当晶粒尺寸由大变小时,Er~(3+)逐渐由红光发射转向绿光发射。通过析晶活化能的分析,确定了NaF可以改善玻璃网络结构,当NaF含量降低时,可以提高玻璃网络结构的完整性,增加玻璃样品的析晶活化能,降低了微晶玻璃样品的析晶能力,进而对微晶玻璃样品内微晶尺寸起到调节作用。因此:当样品中NaF含量较高时,晶粒尺寸较大,晶粒中的Er~(3+)浓度较高,使得Er~(3+)-Er~(3+)之间的交叉驰豫作用增强,导致Er~(3+)红光发射较强;相对应地,NaF含量较低时,晶粒尺寸较小,晶粒中Er~(3+)浓度较低及交叉弛豫减弱,因此,Er~(3+)绿光发射增强。通过改变玻璃组分,调节微晶玻璃中晶粒尺寸,实现了对Er~(3+)在微晶玻璃中发光颜色的调控。 相似文献
992.
The challenging requirements of high safety, low-cost, all-climate and long lifespan restrict most battery technologies for grid-scale energy storage. Historically, owing to stable electrode reactions and robust battery chemistry, aqueous nickel–hydrogen gas (Ni–H2) batteries with outstanding durability and safety have been served in aerospace and satellite systems for over three decades ever since their first development in the 1970s. Despite their satisfactory performances, this technology has difficulty to be applied for grid-scale energy storage primarily because of their high cost resulting from the utilization of expensive platinum as anode hydrogen catalyst. In recent years, with the extensive exploration of inexpensive hydrogen evolution/oxidation reaction catalysts, advanced Ni–H2 batteries have been revived as promising battery chemistry for grid-scale energy storage applications. This mini-review provides an overview of the development activities of Ni–H2 batteries and highlights the recent advances in the application of advanced Ni–H2 batteries for grid-scale energy storage. New cost-effective hydrogen evolution/oxidation reactions catalysts, novel cathode materials, and advanced Ni–H2 battery designs toward further development of Ni–H2 batteries are discussed. The renaissance of advanced Ni–H2 battery technology is particularly attractive for future grid-scale energy storage applications. 相似文献
993.
《无机化学与普通化学杂志》2018,644(15):838-843
A series of lanthanide metal complexes [Ln = Sm ( 1 and 5 ), Eu ( 2 and 6 ), Tb ( 3 and 7 ), Er ( 4 and 8 )] were synthesized with imidazole‐containing β‐diketone ligands. Complexes 1 – 8 were characterized by IR, elemental analysis, powder XRD, and TG measurements. The photoluminescence properties and the probable mechanism of the Sm, Eu, and Tb complexes were studied. The Eu complex generated strong red light in response to excitation with purple light (380–420 nm). Their fluorescence lifetime of 2 and 6 were 378 and 267 μs, respectively. The measurement and analysis of the thermal properties showed that these were thermal stable. Therefore, it can be applied to LED fluorescent powder. 相似文献
994.
《Journal of Electrostatics》2014,72(4):336-341
Rare earth tungsten, 2.2% cerium–tungsten (Ce–W), was used as emission cathode material in thermionic emission electrostatic precipitation. The microstructures and emission properties were investigated. A model was established to estimate cathode lifetime in high temperature and oxygen-bearing atmosphere. Results show that there were not great changes in the inner microstructure of emission materials. But on the surface, tungsten was oxidized to tungsten trioxide and then tungsten trioxide and rare earth oxides evaporated and lost. Decrease of oxygen concentration was effective to prolong operation time of cathode. The increase of temperature reduced cathode lifetime remarkably. 相似文献
995.
Chung-Liang Chang Cuo-Ciang Hsu Ta-Jen Huang 《Journal of Solid State Electrochemistry》2003,7(3):125-128
Various copper oxide cathode materials were studied over a YSZ tube at 800 °C and an oxygen partial pressure of 0.21 atm.
It was found that the cathode performance of CuO may be improved by doping Ag metal into it. However, an optimal doping content
exists and is around 50 mol% Ag. It was also found that copper oxide itself possess enough oxygen vacancies needed for the
role of a mixed conductor. The activation energy for the lattice-oxygen reduction and migration has been calculated to be
55.4 kJ/mol. By the use of electrochemical measurements over Ag-YSZ/CuO electrodes, models for the two-layer electrode have
been proposed and justified for oxygen-ion transport mechanisms at low and high overpotentials, respectively; thus, the roles
of CuO on the cathode behavior of the electron and oxygen-ion conductivities were well identified.
Electronic Publication 相似文献
996.
Optical properties and irradiation effects of Nd3+-, Pr3+-, Tb3+- and Tm3+-doped SrF2 crystals and their possible application to solid-state dosimetry were studied and compared to those induced in pure SrF2 crystals. Optical absorption, thermoluminescence (TL), X- and light-induced luminescence (XL and PL) as well as optically stimulated luminescence and phototransferred TL (OSL and PTTL) were measured in the various samples. Special attention was given to effects of monochromatic vacuum ultraviolet (VUV) radiation. TL was excited in the pure and doped samples by X and β rays as well as by VUV radiation. TL peaks appeared after VUV irradiation at the same temperatures and with the same thermal activation energies as after X or β irradiation, indicating that they are due to the same processes. The VUV excitation spectra showed two maxima at about 145 and 130 nm. Comparison of the TL sensitivities of the various TL materials, showed that the sensitivity of SrF2:Pr3+ was by more than an order of magnitude higher than that of the known LiF:Mg,Ti (TLD-100) phosphor. The sensitivity of pure and of the Nd, and Tb-doped SrF2 were by a factor of 2–4 higher than that of the TLD-100 and that of SrF2:Tm was slightly lower. The main emission bands of SrF2:Pr3+ are located in a convenient spectral region between 460 and 640 nm, where most of the standard photomultipliers are sensitive. The dose dependence of the 460 K TL peak in SrF2:Pr3+ is nearly linear in a wide range up to above 27 000 Gy. 相似文献
997.
The preparation of sol–gel-derived bioactive glass thin films coated on glass is described. Biogel is one of the important modern materials, which are applied in medicine to reduce disability and thus to improve the level of human life. A patient with implanted biogel (i.e. bone, tooth) may be subjected to ionizing radiation during X-ray examination or treatment of cancer. Such an irradiation can generate electron and hole traps in the insulator surface layer. Changes in the microstructure of the biogel surface resulting from irradiation were observed using luminescence methods. Results from luminescence measurements after irradiation of a set of biogel samples are discussed in terms of point defects in the glass structure. 相似文献
998.
999.
Randall K. Reigle Dominick J. Casadonte Jr. Simon G. Bott 《Journal of chemical crystallography》1994,24(12):769-773
The synthesis and crystal structure of a luminescent Cu(I) complex containing triphenylphosphine sulfide and the -diimine 2,9-dimethyl-1, 10-phenanthroline (dmp) is described. The coordination geometry about the Cu(I) center is pseudo-tetrahedral. Interplanar interactions between phenyl groups on the phosphine sulfide ligands and the phenanthroline exist, but are significantly less than those previously reported for the Cu(I) triphenylphosphine analog. The complex displays emission from a single metal-centered charge-transfer state at 77K in a 41 ethanol/methanol (v/v) glass. This is in contrast to the triphenylphosphine complex, which exhibits dual luminescence from a charge-transfer and an intraligand state at 77K. Crystal data: orthorhombic, P212121,a=9.4226(9) Å,b=15.757(1) Å,c=30.494(6) Å,V=4527.4(6) Å3, andR=0.053 (1021 reflections). 相似文献
1000.
液相球化法合成新型正极材料磷酸钒锂 总被引:3,自引:0,他引:3
A novel cathode material lithium vanadium phosphate with the microstructure of submicro-particles aggregate was synthesized by liquid-phase sphericizing granulation. XRD pattern showed that the crystal structure of Li3V2(PO4)3 was monoclinic and belonged to P21/n space group. SEM revealed that the diameters of the particle and aggregated particle were in submicron range and about 10 滋m, respectively, with a narrowdistribution. The electrochemical testing showed that the obtained Li3V2(PO4)3 had the maximum discharge capacity of 126.67 mAh·g-1 and initial coulombic efficiency of 95.6%in the range of 3.0-4.3 V (vs Li/Li+), and 170.47mAh·g-1 and 97.5%in the range of 3.0-4.9 V (vs Li/Li+) at a density of 55.6 mA·g-1, respectively. Moreover, the material had a better cycle stability. 相似文献