Yb和Ni共掺杂对α-MgAgSb室温热电材料的性能调控研究

单一Yb元素掺杂能有效提升α-MgAgSb室温热电材料的热电性能,但Yb元素在α-MgAgSb中较小的固溶度严重限制性能的进一步提升。本文采用Yb和Ni共掺杂来适当增加Yb掺杂元素的固溶度,提高α-MgAgSb的热电性能。结果表明,Yb和Ni原子质量和大小差异均会引起声子散射,极大地降低了α-MgAgSb的热导率,而且Yb和Ni共掺杂能延后双极效应。通过Yb和Ni共掺杂,α-MgAgSb的热电优值峰值达到1.05。     

Ag-N共掺杂ZnO电子结构的理论研究

采用基于DFT理论的第一性原理方法研究了Ag-N共掺杂纤锌矿ZnO的晶格结构和电子结构,计算了包括共掺杂体系的晶格常数、杂质形成能和电子态密度等性质。研究结果显示,共掺改善了杂质原子对体相晶格结构的扰动,提高了掺杂的稳定性。此外,电子结构的计算表明共掺形成的受主能级较单掺时更浅,且空穴态的局域性降低,从而改善了p型ZnO的传导特性,表明受主共掺可能是一种比较有潜力的p型ZnO掺杂方式。计算与实验结果符合,为受主共掺形成p型ZnO的机理提供了理论支持。     

Insights into structure,local site symmetry,and energy transfer for regulating luminescent properties of SrLaLiTeO6: Dy/Eu and its application in wLEDs

A series of spectrally tunable Dy³⁺/Eu³⁺-coactivated double perovskites SrLaLiTeO₆ (SLLT) were synthesized via solid-state ceramic route under air condition. Considering differences of ionic radius and valences among the dopants and host cations, Dy³⁺/Eu³⁺ are all inclined to enter La site, though slight occupations in Sr site cannot be completely ruled out. Dy shows narrow band emissions in blue (B) to yellow (Y) region, which is stemmed from magnetic (⁴F_9/2 → ⁶H_15/2) and electric (⁴F_9/2 → ⁶H_13/2) dipole transitions, respectively. Eu³⁺ exhibits orange-red (O–R) emissions, with two dominant peaks located at ∼ 593 and 617 nm from magnetic (⁵D₀ → ⁷F₁) and electric (⁵D₀ → ⁷F₂) dipole transitions, which could be used as compensation for the red-emitting portion in pc-wLEDs via energy transfer (ET) from Dy to Eu to overcome the disadvantage of low excitation efficiency. The substitutional local site symmetry could be regularly modified along with severely impacting on Y/B and R/O ratios for Dy and Eu emission colors via simply modifying the doping contents, due to changes in bond lengths and Coulomb potentials from interconnected octahedrons [LiO₆] and [TeO₆] around the dopants. The fabricated pc-wLED via combining a commercial n-UV LED chip with the SLLT: Dy/Eu, exhibited splendid EL performance, with the CIE coordinate is calculated to be (0.3690, 0.3539), CCT of 3232 K, and CRI (R_a) of 86.5. Altogether, it manifests that the stable SLLT: Eu and SLLT: Dy/Eu are potentially good candidates for applications as red and white phosphors, respectively in indoor plant growth LED and pc-wLEDs.     

以多孔陶粒为载体的纳米Ag/N-TiO_2光催化膜的制备与表征

以多孔陶粒为载体,采用改进的溶胶-凝胶工艺成功地制备了具有可见光催化活性的纳米Ag/N-TiO2膜.研究了Ag,N或Ag/N的掺杂对TiO2的晶相结构、粒度、成分和光催化活性的影响.采用X射线衍射、紫外-可见分光光谱分析、X射线能谱仪和扫描电子显微镜进行了表征.以含油的废水和新鲜球菌为污染物模型估算其光催化活性和抗菌杀菌性.结果表明:银和氮的复合掺杂对纳米TiO2膜的光催化活性显著改善.负载Ag/N-TiO2膜的多孔陶粒对水中的油和细菌的降解速率是纯TiO2陶粒的3倍多.这种陶粒可用于油水处理和养鱼池的抗菌杀菌及过滤处理.     

Effect of Y3+ codoping on luminescence decays of the 4I13/2 level in Er3+-doped Al2O3 powders prepared by a sol-gel method

The luminescence lifetime of the 0.01 mol.%-0.1 mol.% Er³⁺- and 0–20 mol.% Y³⁺-codoped Al₂O₃ powders prepared at a sintering temperature of 900°C in a non-aqueous sol-gel method has been investigated to explore the enhanced mechanism of photoluminescence properties of the Er³⁺-doped Al₂O₃ by Y³⁺ codoping. For the 0.1 mol.% Er³⁺-Y³⁺-codoped Al₂O₃ powders, the measured lifetime of Er³⁺ gradually increases with increasing Y³⁺ concentration. Consequently, codoping with 20 mol.% Y³⁺ leads to an increase in the measured lifetime from 3.5 to 5.8 ms. By comparing the measured lifetime for different Er³⁺ concentrations in the Al₂O₃ powders, the radiative lifetime of both the Er³⁺-doped and the Er³⁺-Y³⁺-codoped Al₂O₃ powders is estimated to be about 7.5 ms. Infrared absorption spectra indicate that Y³⁺ codoping does not change the-OH content in the Er³⁺-Y³⁺-codoped Al₂O₃ powders. The prolonged luminescence lifetime of the ⁴I_13/2 level of Er³⁺ in Er³⁺-doped Al₂O₃ powders by Y³⁺ codoping is ascribed to the decrease in the energy transfer rate between the Er³⁺ ions and the Er³⁺ and -OH, respectively, due to the suppressed interaction between Er³⁺ ions.     

In-N codoped p-type ZnMgO thin films with bandgap engineering

In-N codoped p-type ZnMgO films have been prepared by direct current reactive magnetron sputtering. The effect of Mg content on the properties of In-N codoped ZnMgO films was examined. The Mg content in the film is directly proportional to that in the target suggesting the same sputtering mechanism of Zn and Mg. The p-type behaviour of ZnMgO films was deteriorated with the Mg content increasing. The bandgap engineering, due to the fact of Mg substituting Zn, was realized in p-type ZnMgO films.     

共掺铝的掺铒光纤放大器的光谱特性

用Stark能级分裂的变化分析了掺铝改变掺铒光纤放大器(EDFA)光谱特性的原理，并用改进型化学气相沉积法(MCVD)结合溶液浸泡掺杂法制作了采用不同掺铝比例的掺铒光纤，测试了用这几种光纤制作的放大器的自发辐射谱，得出掺铝浓度的提高使荧光谱的峰值往短波长移动，与Stark能级分裂理论分析得到的结果相一致。同时采用截断法测试了两种不同掺铝浓度的掺铒光纤的吸收谱，实验结果表明掺铒光纤中增加铝的含量将提高铒离子浓度，并提高掺铒光纤的吸收系数，减短掺铒光纤放大器中的掺铒光纤长度。高掺铝掺铒光纤放大器具有更宽更平坦的增益谱线，可以适用长距离波分复用(WDM)系统。     

第一性原理研究N/V 和 C/Cr双掺杂锐钛矿型TiO2光催化剂的协同效应

非金属（C或N）和过渡金属（V或Cr）掺杂是一种能够有效地调整锐钛矿型TiO2的光电化学性能的补偿型掺杂方法。本文采用平面波超软赝势方法计算了不同物种掺杂的补偿型双掺杂TiO2的形成能和电子结构来研究其稳定性和在可见光区域的光敏性,计算结果表明采用过渡金属双掺杂有利于提高p型掺杂（N和C）的浓度。尤其是补偿型掺杂不仅可以通过减小能隙来提高光吸收性能,消除局域捕获来提高载流子的移动和转化效率,并且能够保持导带边缘的氧化还原势。这些结果有助于理解双掺杂提高TiO2光催化活性的协同作用机制。     

Nitrogen and Phosphorus Codoped Vertical Graphene/Carbon Cloth as a Binder‐Free Anode for Flexible Advanced Potassium Ion Full Batteries

With the fast development in flexible electronic technology, power supply devices with high performance, low‐cost, and flexibility are becoming more and more important. Potassium ion batteries (KIBs) have a brilliant prospect for applications benefiting from high voltage, lost cost, as well as similar electrochemistry to lithium ion batteries (LIBs). Although carbon materials have been studied as KIBs anodes, their rate capability and cycling stability are still unsatisfactory due to the large‐size potassium ions. Herein, a nitrogen (N) and phosphorus (P) dual‐doped vertical graphene (N, P‐VG) uniformly grown on carbon cloth (N, P‐VG@CC) is reported as a binder‐free anode for flexible KIBs. With the combined advantages of rich active sites, highly accessible surface, highly conductive network, larger interlayer spacing as well as robust structural stability, this binder‐free N, P‐VG@CC anode exhibits high capacity (344.3 mAh g^?1), excellent rate capability (2000 mA g^?1; 46.5% capacity retention), and prominent long‐term cycling stability (1000 cycles; 82% capacity retention), outperforming most of the recently reported carbonaceous anodes. Moreover, a potassium ion full cell is successfully assembled on the basis of potassium Prussian blue (KPB)//N, P‐VG@CC, exhibiting a large energy density of 232.5 Wh kg^?1 and outstanding cycle stability.     

V、La共掺杂对纳米TiO2光催化降解甲基橙的研究

采用Sol-gel法制备了V-La共掺杂纳米TiO2光催化剂,XRD结果表明,制备的催化剂为锐钛矿型.以甲基橙水溶液为模拟对象,分别从光照时间、催化剂用量、酸度大小三个方面考察了复合光催化剂的光催化活性,结果表明,V-La共掺杂纳米TiO2光催化剂的光催化活性均高于单掺或不掺杂催化剂.