Pr3+/Yb3+ 共掺氟锆酸盐玻璃的热分析

在对不同ＰｂＦ２呈的Ｐｒ＾３＋／Ｙｂ＾３＋共拓的ＺＢＬＡＰＮ玻璃的差热分析后同烧结发现含ＰｂＦ２大于４．５％后，差热曲线上的析晶峰出现分裂，经扫描电镜分析，含铜量高的玻璃中出现了分相，各相所含铅量不同，这引起玻璃热稳定下降。     

Dopant Occupancy in MgO-Codoped Lithium Niobate Crystals

On the basis of the bond valence model, the preferential occupancy of various dopant such as Mn2 , Eu3 , Er3 , Nd3 , Lu3 , Yb3 , In3 , Cr3 , Fe3 and Ti4 in the ideal stoichiometric lithium niobate (SLN) crystallographic frame was investigated in a viewpoint of chemical bonds. Theoretical analysis indicates that the dopant occupancy is significantly influenced by the anti-site Nb4 Li. Our work also shows that Mg-like ions (Mg2 , Zn2 , In3 , Sc3 ) have a repulsive effect on Nb4 Li ions. When removing Nb4 Li ion by codoping Mg-like ions, the dopant occupancy in the LN crystallographic frame is determined by the natural characteristics of dopant, which is consistent well with the result in the ideal SLN crystals.     

近化学计量比Cu:Fe:LiNbO3晶体的生长及蓝光优化光折变性能

以K2O为助溶剂在LiNbO3中掺入0.15%(质量分数,下同)CuO,0.03%和0.05%Fe～03,用顶部籽晶溶液生长法生长近化学计量比Cu:Fe:LiNbO3晶体.以Ar+激光器的488nm激光为光源测试Cu:Fe:LiNbO3晶体的光激载流子类型,采用二波耦合光路测试了晶体的光折变存储性能,并与633nm红光...     

Enhanced optical absorption and photocatalytic activity of Cu/N-codoped TiO2 nanocrystals

Cu/N-codoped TiO₂ nanoparticles were prepared by sol–gel technique. Their structure, surface chemical composition, and optical absorption were characterized. All as-prepared samples consisted of the anatase phase. It was found that Cu atoms replaced Ti atom sites, and N atoms occupied the O atom sites and interstitial sites in the TiO₂ lattice. The optical absorption results reveal that Cu/N codoping could greatly enhance the absorption of TiO₂ in the entire visible region, leading to a decrease in the band-gap energy of TiO₂. It also significantly enhanced the solar-driven catalytic activity of TiO₂ in the degradation of methylene blue in solution. The sample 2.0 at% Cu/N-codoped TiO₂ displayed the highest solar-driven catalytic efficiency among all tested samples.     

ZnO薄膜p型转变的难点及解决新方法

论述了ZnO薄膜p型转变的难点及其解决方法的最新研究进展,并讨论了Al N H共掺杂生长p-ZnO薄膜的掺杂机制,提出多层缓冲层生长工艺以实现p-ZnO薄膜的可控掺杂,进而优化薄膜性能.     

衬底温度对Al+N共掺p-ZnO薄膜性能的影响

目前,制备性能优异的p-ZnO薄膜的可重复性问题已成为制约ZnO基光电器件发展的一个主要因素.本文利用直流反应磁控溅射技术,以X射线衍射,霍尔效应测试,X射线光电子能谱及透射光谱为表征手段,研究了不同衬底温度对Al+N共掺p-ZnO薄膜电学、光学、结晶性能的影响,并从N2O的分解反应及衬底表面各种原子的迁移过程提出导致薄膜性能差异的原因.在最佳衬底温度(500℃)时,p-ZnO薄膜空穴浓度达2.52×1017cm-3,电阻率为28.3Ω·cm.     

Co-Doping Effect of Mn and Y on Charge and Mass Transport Properties of BaTiO3

BaTiO₃-based multilayer-ceramic capacitors (MLCC) using base metal (Ni) electrodes normally contains Mn and Y each approximately on the order of 0.5 mol%. It is only empirically known that the co-doping of Y and Mn facilitates sintering with the base-metal electrodes as well as improves the device performance and life time. In order to understand the effect of the co-doping, we have measured the electrical conductivity and chemical diffusivity on polycrystalline BaTiO₃ that is co-doped with Y and Mn each by 0.5 mol% against oxygen partial pressure at elevated temperatures. It is found that while the n-type conductivity in reducing atmospheres (e.g., Po₂ < 10^{– 6} atm at 1000C) remains similar to that of undoped or acceptor-doped BaTiO₃, its p-type conductivity in oxidizing atmospheres (e.g., Po₂ > 10^{– 6}at 1000C) is remarkably suppressed compared to the latter. The chemical diffusivity is also similar to that of the latter in magnitude (e.g., 10^{– 2}–10^{– 5} cm²/s at 1000C), but its trend of variation with oxygen partial pressure is rather opposite. These variations of the conductivity and chemical diffusivity are mainly attributed to Mn ions changing their valence from +2 to +3 to +4 with increasing oxygen partial pressure. It is explained from a defect-chemical view why the codoping of fixed-valent donor (Y) and variable-valent acceptor (Mn) has been practiced in MLCC processing.     

Theoretical and experimental investigation of aluminum‐boron codoping of silicon

We present a detailed study on aluminum‐boron codoping of silicon by alloying from screen‐printed aluminum pastes containing boron additives (Al–B pastes). We derive an analytical model for the formation of the Al–B acceptor profiles by quantitatively describing (i) the composition of the Al–B–Si melt and (ii) the incorporation of Al and B acceptor atoms into the recrystallizing Si lattice. We show that measured Al–B dopant profiles can be excellently described by this model, which therefore offers a straightforward method for the comprehensive investigation of alloying from Al–B pastes. The formation of a characteristic kink in the Al–B dopant profile curve can thus be ascribed to the exhaustion of the B additive dissolution during alloying. By intentionally adding elemental B powder to an Al paste, we demonstrate that only a low percentage of the B powder actually dissolves into the melt. We show that this incomplete dissolution of the B additive strongly affects the recombination characteristics of Al–B–p⁺ regions and, thus, is an important element of alloying from Al–B pastes. This study therefore provides improved understanding of aluminum‐boron codoping of silicon. Copyright © 2015 John Wiley & Sons, Ltd.     

Enhancing the Quantum Anomalous Hall Effect by Magnetic Codoping in a Topological Insulator

The quantum anomalous Hall (QAH) effect, which has been realized in magnetic topological insulators (TIs), is the key to applications of dissipationless quantum Hall edge states in electronic devices. However, investigations and utilizations of the QAH effect are limited by the ultralow temperatures needed to reach full quantization—usually below 100 mK in either Cr‐ or V‐doped (Bi,Sb)₂Te₃ of the two experimentally confirmed QAH materials. Here it is shown that by codoping Cr and V magnetic elements in (Bi,Sb)₂Te₃ TI, the temperature of the QAH effect can be significantly increased such that full quantization is achieved at 300 mK, and zero‐field Hall resistance of 0.97 h/e² is observed at 1.5 K. A systematic transport study of the codoped (Bi,Sb)₂Te₃ films with varied Cr/V ratios reveals that magnetic codoping improves the homogeneity of ferromagnetism and modulates the surface band structure. This work demonstrates magnetic codoping to be an effective strategy for achieving high‐temperature QAH effect in TIs.     

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.