Ce掺杂对La1-xCexCoO3催化剂的结构和催化氧化性能的影响

采用非晶态配合物的方法合成了La1-xCexCoO3(x=0、0.05、0.1、0.2、0.3)催化剂, 并采用X射线衍射(XRD)、透射电镜(TEM)和比表面测定仪(BET)等手段对催化剂的微观结构进行了研究. 揭示了Ce掺杂对催化剂的钙钛矿结构, CO催化氧化以及催化氧化发光性能的影响规律. 结果表明, 在Ce4+掺杂部分取代La3+后, 催化剂形成了镧不足的La1-xCeyφx-yCoO3(φ是A位离子空位)钙钛矿相以及CeO2和Co3O4物相. 与LaCoO3催化剂相比, x=0.1催化剂的CO催化氧化活性最高(T100%=290 ℃). La1-xCexCoO3催化剂对CO催化氧化发光的响应与其催化活性密切相关.     

Enhancement of positive temperature coefficient resistance effect of BaTiO3-based semiconducting ceramics caused by B2O3 vapor dopants

The positive temperature coefficient resistivity (PTCR) effect of semiconducting BaTiO₃ ceramics can be remarkably influenced by both dopants and ceramic processing. The behavior of B₂O₃ as vapor dopants was studied in this paper. It was found that the PTCR effect was enhanced distinctly, while the room temperature resistance also increased.     

Investigation of the effect of acid dopant on the physical properties of polyaniline prepared using microwave irradiation

The microwave (MW) synthesis of polyaniline (PANI) is performed using potassium iodate (KIO₃) as oxidizing agent in different concentrations of aqueous hydrochloric acid (HCl) at 8 and 93 W applied microwave power for duration of 10 min. The morphological and structural changes in synthesized MW PANI samples are investigated using Scanning Electron Microscopy (SEM) and Fourier transform Infrared Spectroscopy (FTIR). With decreasing pH of the reaction medium the morphology of MW PANI samples changed from slab-like with a small amount of fibrils to porous products which consist of short, rod-like structures. The FTIR spectra confirm that the microwave generated materials structurally consist of PANI, but aniline oligomer peaks are observed in the FTIR at 725 and 686 cm⁻¹ for MW PANI synthesized using 0.5 M aqueous HCl. The influence of acid dopant on the spin concentration of MW PANI synthesized at 8 and 93 W are examined.     

横截面积参数对钛氧化物忆阻器导电特性的影响

纳米钛氧化物忆阻器的导电过程因自身参数的改变及不同机理的共存而呈现复杂特性,但现有研究缺乏针对横截面积参数的改变对忆阻器导电特性影响的讨论.基于杂质漂移及隧道势垒机理,本文分析了忆阻器导电过程,研究了横截面积参数与导电过程中各关键物理要素间的关联,并基于此,分别研究了钛氧化物横截面积及隧道势垒横截面积的改变对忆阻器导电特性的影响,分析了两者的区别与联系.验证了两种机理共存情况下,相对于钛氧化物横截面积的改变,隧道势垒横截面积的改变是引发忆阻器导电特性变化的主要因素,且是导致忆阻器非理想导电特性的可能因素.研究成果有助于进一步解释忆阻器导电过程的复杂性,并为优化忆阻器模型的构建提供依据.     

Characteristics of wide-band reflection of polymer-stabilised cholesteric liquid crystal cell prepared from an unsticking technique

An unsticking technique was applied for the fabrication of a polymer-stabilised cholesteric liquid crystal (PSCLC) cell. The template of polymer matrix in the planarly aligned cholesteric liquid crystal (Ch-LC) was perfectly preserved by lifting off the hydrophilic antisticking substrate. The desired PSCLC cell could then be obtained by injecting a third Ch-LC sample between two designed templates of PSCLC layer. By adjusting the pitch distribution in the two stacking templates, a reflectivity of nearly 50% incident light could be yielded and the bandwidth of the reflection spectrum could be controlled accurately in the PSCLC cell. Thus, a method to modulate the wide-band reflection of 50% visible light flux range was offered.     

镁离子掺杂多孔硅的蓝光发射

用电化学方法对多孔硅薄膜进行了镁离子的化学掺杂.用荧光分光光度计分析了样品的光致发光特性,发现镁掺杂增强了多孔硅的蓝光发射,当镁离子浓度增大到0.002mol/L时,可使蓝光强度达到多孔硅红光强度的一半.红外吸收谱表明,掺镁多孔硅的表面形成较完整的Si-O-Si网络结构,分析结果认为,多孔硅的蓝光光激发主要发生在多孔硅的纳米硅粒中,光发射主要发生在多孔硅中包裹纳米硅SiOx层中的发光中心上,对实验结果进行了合理的解释.     

路易斯碱负离子掺杂有机半导体:原理、应用和展望

掺杂是改善有机半导体载流子浓度和电荷输运能力的有效方法.路易斯碱负离子电子转移掺杂有机半导体,逐渐发展成为了一种温和、可控和可溶液加工的n型掺杂方法,并在有机光电器件中展现出较好的应用.本综述旨在探讨路易斯碱负离子和n型半导体之间的电子转移机制及其影响因素,总结基于该策略开发的界面材料和活性层掺杂等方面的应用,并展望其未来的发展方向.     

Control of the binding energy by tuning the single dopant position,magnetic field strength and shell thickness in ZnS/CdSe core/shell quantum dot

Recently, the new tunable optoelectronic devices associated to the inclusion of the single dopant are in continuous emergence. Combined to other effects such as magnetic field, geometrical confinement and dielectric discontinuity, it can constitute an approach to adjusting new transitions. In this paper, we present a theoretical investigation of magnetic field, donor position and quantum confinement effects on the ground state binding energy of single dopant confined in ZnS/CdSe core/shell quantum dot. Within the framework of the effective mass approximation, the Schrödinger equation was numerically been solved by using the Ritz variational method under the finite potential barrier. The results show that the binding energy is very affected by the core/shell sizes and by the external magnetic field. It has been shown that the single dopant energy transitions can be controlled by tuning the dopant position and/or the field strength.     

Solid polymers doped with rare earth metal salts. II. Thermal behavior and morphology of the neodymium acetate–poly(ethylene oxide) system

Samples of poly(ethylene oxide), PEO, doped with neodymium acetate, Nd (Act)₃, were prepared and found to be microphase separated. At an EO/Nd (Act)₃ molar ratio no less than 4, wide-angle x-ray diffraction (WAXD) patterns and small-angle x-ray scattering (SAXS) data suggest that bulk Nd (Act)₃ and ionic clusters are both absent. It is inferred from differential scanning calorimetry (DSC) thermograms that in the presence of PEO, Nd (Act)₃ forms an amorphous phase which is different from the amorphous phase formed by Nd (Act)₃ alone. The tighter binding of CH₃COO^- to Nd³⁺, in comparison to Cl^-, appears to be responsible for the lack of true dissolution of Nd (Act)₃ in PEO, a behavior clearly distinct from a number of polymer-metal salt complexes reported in the literature. © 1993 John Wiley & Sons, Inc.