Nanostructural control in solution-derived epitaxial Ce(1-x)Gd(x)O(2-y) films

A novel mechanism based on aliovalent doping, allowing fine tuning of the nanostructure and surface topography of solution-derived ceria films, is reported. While under reducing atmospheric conditions, non-doped ceria films are inherently polycrystalline due to an interstitial amorphous Ce(2)C(3) phase that inhibits grain growth, a high quality epitaxial film can be achieved simply by doping with Gd(3+) cations. Gd(3+) [Formula: see text] Ce(4+) substitutions within the lattice are accompanied by charge-compensating oxygen vacancies throughout the volume of the crystallites acting as an efficient vehicle to reduce the barrier for grain boundary motion caused by interstitial Ce(2)C(3). In this way, the original nanostructure is self-purified by pushing the amorphous Ce(2)C(3) phase towards the free surface of the film. Once a full epitaxial cube-on-cube oriented ceria film is obtained, its surface morphology is dictated by the interplay between faceting on low energy {110} and/or {111} pyramidal planes and truncation of those pyramids by (001) ones. The development of the latter requires the suppression of their polar character which is thought to be achieved by charge compensation between the dopand and oxygen along [Formula: see text] directions.     

Electrical properties of nanocrystalline Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta) (0.1 < or = x < or = 0.3) ceramics for IT-SOFC

Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta) (0.1 < or = x < or = 0.3) nano-sized powders were successfully synthesized by the solution combustion synthesis process. The calcined nanopowders showed a ceria-based single phase with a cubic fluorite structure. In this study, we discussed the structural and electrical characteristics of the sintered Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta). We obtained high-quality Ce(0.8)Sm(0.2)O(2-delta) and Ce(1-x)Gd(x)O(2-delta) ceramics with a high density, ultra-fine grain size, and high electrical conductivity even at low sintering temperature using the nanosized powders. The electrical conductivities at 800 degrees C for the Ce(0.8)Sm(0.2)O(2-delta) sintered at 1400 degrees C and the Ce(0.8)Gd(0.2)O(2-delta) sintered at 1350 degrees C were 0.110 and 0.104 Scm(-1), respectively.     

Elaborately Designed Hierarchical Heterostructures Consisting of Carbon‐Coated TiO2(B) Nanosheets Decorated with Fe3O4 Nanoparticles for Remarkable Synergy in High‐Rate Lithium Storage

The capacity and conductivity deficiencies of TiO₂(B) are addressed simultaneously through a smart morphological and compositional design. Elaborately designed hierarchical heterostructures are reported, consisting of carbon‐coated TiO₂(B) nanosheets decorated with Fe₃O₄ nanoparticles, based on a facile self‐assembly strategy. The novel hierarchical heterostructures exhibit a remarkable synergy by bridging the intriguing functionalities of TiO₂(B) nanosheets (high safety and durability), Fe₃O₄ nanoparticles (high theoretical capacity), and carbon coatings (high conductivity), which results in significantly improved cycle and rate performances. A startlingly high reversible capacity of 763 mA h g⁻¹ is delivered at 500 mA g⁻¹ after 200 charging−discharging cycles. Even when the current density is as high as 10 000 mA g⁻¹, the reversible capacity is still up to 498 mA h g⁻¹. This smart morphological and compositional design opens up new opportunities for developing novel, multifunctional hierarchical heterostructures as promising anode materials for next‐generation, high‐power lithium‐ion batteries.     

Preparation of thin epitaxial multilayer YBa2Cu3O7−x (Ag) films by aerosol deposition

Thin-textured YBa₂Cu₃O _y (Ag) films were prepared by a new CVD process consisting of aerosol deposition and low temperature annealing, both operations not exceeding 600°C. MgO and SrTiO₃ single crystals were used as substrates. The stoichiometry of the prepared films was not ideal 1–2–3, having the atomic quotient of copper always lower than 3. For an unoptimized preparation process, the onset temperatures were around 80 K and the zero resistanceT _c values around 70K. Properties of samples obtained by low-temperature annealing are compared with those obtained by high temperature annealing. “Cleaning” effect of vacuum-annealing upon removing the nitrate and hydroxide groups from the prepared films is supposed.     

Fabrication of silicon oxide nanodots with an areal density beyond 1 teradots inch(-2)

The combination of solvent annealing, surface reconstruction, and a tone-reversal etching procedure provides an attractive approach to utilize block copolymer (BCP) lithography to fabricate highly ordered and densely packed silicon oxide nano-dots on a surface. The obtained silicon oxide nano-dots feature an areal density of 1.3 teradots inch(-2) .     

Dy~(3+)/Tb~(3+)掺杂高钆镥闪烁玻璃光谱性能

用高温熔融法制备了Dy3+/Tb3+掺杂的高钆镥氟氧化物闪烁玻璃样品,测试分析了其吸收光谱、激发与发射光谱及衰减曲线等。研究了Dy3+和Tb3+离子浓度增加对Tb3+离子发光的影响以及Dy3+离子的浓度猝灭效应;通过IH理论模型分析了Dy3+和Tb3+离子的能量传递方式和能量传递效率。结果表明Dy3+离子对Tb3+离子发光具有敏化作用,随着Dy3+离子浓度增加敏化作用增强,但是当Dy3+离子的浓度达到2%(摩尔分数)以上时,随着Dy3+离子浓度的增加,Tb3+离子的发光强度降低;Dy3+和Tb3+离子的能量传递方式为无辐射能量传递方式,且能量传递效率可以达到60%以上。     

Layer‐by‐Layer Approach to (2+1)D Photonic Crystal Superlattice with Enhanced Crystalline Integrity

Large‐area polystyrene (PS) colloidal monolayers with high mechanical strength are created by a combination of the air/water interface self‐assembly and the solvent vapor annealing technique. Layer‐by‐layer (LBL) stacking of these colloidal monolayers leads to the formation of (2+1)D photonic crystal superlattice with enhanced crystalline integrity. By manipulating the diameter of PS spheres and the repetition period of the colloidal monolayers, flexible control in structure and stop band position of the (2+1)D photonic crystal superlattice has been realized, which may afford new opportunities for engineering photonic bandgap materials. Furthermore, an enhancement of 97.3% on light output power of a GaN‐based light emitting diode is demonstrated when such a (2+1)D photonic crystal superlattice employed as a back reflector. The performance enhancement is attributed to the photonic bandgap enhancement and good angle‐independence of the (2+1)D photonic crystal superlattice.     

Rational Design of Na(Li1/3Mn2/3)O2 Operated by Anionic Redox Reactions for Advanced Sodium‐Ion Batteries

In an effort to develop high‐energy‐density cathodes for sodium‐ion batteries (SIBs), low‐cost, high capacity Na(Li_1/3Mn_2/3)O₂ is discovered, which utilizes the labile O 2p‐electron for charge compensation during the intercalation process, inspired by Li₂MnO₃ redox reactions. Na(Li_1/3Mn_2/3)O₂ is systematically designed by first‐principles calculations considering the Li/Na mixing enthalpy based on the site preference of Na in the Li sites of Li₂MnO₃. Using the anionic redox reaction (O^2?/O^?), this Mn‐oxide is predicted to show high redox potentials (≈4.2 V vs Na/Na⁺) with high charge capacity (190 mAh g^?1). Predicted cathode performance is validated by experimental synthesis, characterization, and cyclic performance studies. Through a fundamental understanding of the redox reaction mechanism in Li₂MnO₃, Na(Li_1/3Mn_2/3)O₂ is designed as an example of a new class of promising cathode materials, Na(Li_1/3M_2/3)O₂ (M: transition metals featuring stabilized M⁴⁺), for further advances in SIBs.