加拿大东部斯科舍盆地塞布尔次盆下白垩统深水重力流沉积研究

针对加拿大东部斯科舍盆地重力流沉积演化研究不足的问题,综合岩心、测井、地震及磁异常等资料,明确斯科舍盆地塞布尔次盆下白垩统重力流沉积单元,揭示其沉积演化并探讨发育控制因素。研究结果表明：斯科舍盆地塞布尔次盆下白垩统密西沙加组和洛根峡谷组发育规模性重力流沉积,可以识别出块体搬运、重力流水道、天然堤及朵叶体等沉积单元;密西沙加组沉积初期（距今147 Ma）研究区西部发育小型重力流沉积,沉积末期（距今130Ma）研究区中部发育大型坡底扇;洛根峡谷组沉积初期（距今113 Ma）研究区普遍发育小型重力流沉积,沉积末期（距今101 Ma）研究区东南部发育大型坡底扇。陆架边缘三角洲进积及陆坡窄、陡,分别为重力流发育提供了物质基础和动力条件。     

CO2驱凝胶封窜体系研究进展

由于油气间黏度差异大和油藏的非均质性,在CO2驱油过程会发生气窜从而降低CO2的波及效率。凝胶体系是CO2驱油过程中的有效封窜剂,在中外都有着广泛的应用。介绍了延缓交联聚丙烯酰胺凝胶、预交联凝胶颗粒、两级封窜凝胶体系、泡沫凝胶这4种凝胶体系的封窜机理以及研究进展。延缓交联丙烯酰胺凝胶流动性强,价格低廉,但是成胶强度、成胶时间不可控并且不耐酸性腐蚀。预交联凝胶颗粒成胶时间、成胶强度可控且耐高温耐高矿化度,但是粒度较大,无法进入渗透率较低的地层。两级封窜凝胶体系结合了刚性凝胶与小分子的优势,能够同时封堵不同尺寸的裂缝,但是对于超过特定尺寸的裂缝,封堵效果将会下降。泡沫凝胶对地层伤害小,但是不耐高温。目前,用于CO2驱气窜的凝胶体系存在着不耐酸性腐蚀的问题,如何使长期处于CO2酸性环境下的凝胶体系保持稳定是未来的研究方向。     

Separation of propylene and propane with a microporous metal–organic framework via equilibrium-kinetic synergetic effect

Adsorption separation of olefin and paraffin can greatly lower the energy consumption associated with the currently utilized distillation technique but remains a great challenge. Herein, we report the efficient separation of propylene (C₃H₆) and propane (C₃H₈) in a phosphate anion-functionalized metal–organic framework (MOF) ZnAtzPO₄ by synergetic effect of equilibrium and kinetics. The material features periodically expanded and contracted apertures decorated with electronegative groups, offering eligible pore shape and pore chemistry to effectively trap C₃H₆ under moderate isosteric heat of adsorption (27.5 kJ mol⁻¹) while obstruct the diffusion of C₃H₈. It simultaneously combines excellent thermodynamic selectivity (uptake ratio of 1.71) and kinetic selectivity (~31) for C₃H₆/C₃H₈ separation, meanwhile can be easily regenerated. Breakthrough experiment for C₃H₆/C₃H₈ gas mixture was conducted and confirmed the outstanding separation capability of ZnAtzPO₄. The equilibrium and kinetics cooperative C₃H₆/C₃H₈ adsorption separation was for the first time found in anion-functionalized MOFs, and further confirmed by computational studies.     

Electric field assisted solid-state interfacial joining of TaC-HfC ceramics without filler

The application of ultra-high-temperature ceramics (UHTCs) demands effective ways of joining in overcoming the problems associated with the fabrication of complex-shaped components. In this study, we choose to investigate a new method of rapidly joining pre-sintered TaC and HfC ceramics without any filler material using the spark plasma sintering (SPS) technique. A well-bonded TaC–HfC interface was observed with no apparent cracking and porosity at the joint. The joining mechanisms were predominantly driven by solid-state diffusion and localized plastic deformation. The nanomechanical properties of the TaC-HfC joint are better than the HfC while comparable to that of the TaC. High-load indentation (up to 200 N) results suggest that the TaC–HfC interface is stronger than the parent UHTCs with no crack propagating at the interface. Upon comparison with the parent UHTCs, the damaged area and the average crack length at the interface, reduced up to ~94% and ~56%, respectively. This study shows that the SPS technique can also apply to joining other UHTCs without any filler, resulting in the new field of developing complex components for the thermal protection system (TPS).     

Simultaneously achieved high-energy storage density and efficiency in (K,Na)NbO3-based lead-free ferroelectric films

With the development of advanced electrical and electronic devices and the requirement of environmental protection, lead-free dielectric capacitors with excellent energy storage performance have aroused great attention. However, it is a great challenge to achieve both large energy storage density and high efficiency simultaneously in dielectric capacitors. This work investigates the energy storage performance of sol-gel-processed (K,Na)NbO₃-based lead-free ferroelectric films on silicon substrates with compositions of 0.95(K_0.49Na_0.49Li_0.02)(Nb_0.8Ta_0.2)O₃-0.05CaZrO₃-x mol% Mn (KNN-LT-CZ5-x mol% Mn). The appropriate amount of Mn-doping facilitates the coexistence of orthorhombic and tetragonal phases, suppresses the leakage current, and considerably enhances the breakdown strengths of KNN-LT-CZ5 films. Consequently, large recoverable energy storage density up to 64.6 J cm⁻³ with a high efficiency of 84.6% under an electric field of 3080 kV cm⁻¹ are achieved in KNN-LT-CZ5-5 mol% Mn film. This, to the best of our knowledge, is superior to the majority of both the lead-based and lead-free films on silicon substrates and thus demonstrates great potentials of (K,Na)NbO₃-based lead-free films as dielectric energy storage materials.     

Valence-induced effects on the electrical properties of NiMn2O4 ceramics with different Ni sources

Spinel-structured NiMn₂O₄ ceramics, with different valence Ni sources, were originally prepared using Ni₂O₃ and NiO as raw materials, and the effects of different valence Ni sources on their electrical properties were first investigated. XRD patterns show that both Ni₂O₃-based and NiO-based NiMn₂O₄ ceramics are single cubic spinel structures. SEM/EDS images indicate that the NiMn₂O₄ ceramics exhibited high density at the experiment-determined sintering temperatures. XPS results and Raman drifts prove that the Ni valence-induced changes in Mn ions at B sites played a significant role in the electrical properties and thermal stability of NiMn₂O₄ ceramics. Compared with NiO-based NiMn₂O₄, the resistivity at 25°C (ρ_25°C) of Ni₂O₃-based NiMn₂O₄ increased dramatically from 3109 to 106958 Ω cm, the thermal constant (B_25/50) increased from 3264 to 4473 K, and the resistance shifts after annealing for 1000 h at 150°C decreased from 0.80% to 0.74%. The investigation of the relationship between the material properties and valence of Ni sources has provided a new and effective way for designing the spinel-structured negative temperature coefficient (NTC) materials by modulating the valence of ions at A sites in the raw materials.     

Preparation of ZrO2 beads by an improved micro-droplet spray forming process

Monodisperse ZrO₂ ceramic beads with size larger than 1 mm have been prepared by an improved micro-droplet spray forming process, through which a compressor and a dispenser were employed to produce droplets continuously. Furthermore, the slurry recipe and drying temperature have been optimized to enhance the sphericity and smoothness of the beads. The sintered ZrO₂ ceramic beads present promising mechanical performance, including a relative density of 84.6%, a crush strength of 256.2 ± 36.6 N as well as a Vickers hardness of 1344.4 ± 58.3 HV. Such procedure reveals great potential in mass production of ceramic beads.     

Ti4+ modified MgZrNb2O8 microwave dielectric ceramics with an ultra-high quality factor

Ti⁴⁺-modified MgZrNb₂O₈ (MgZr_1-xTi_xNb₂O₈, x = 0, 0.1, 0.2, 0.3, 0.4) ceramics were synthesized using the traditional solid-state reaction method. Pure MgZr_1–xTi_xNb₂O₈ was detected without any secondary phase via the X-ray diffraction patterns. According to the sintering behavior and the surface morphology results, the introduction of Ti⁴⁺ reduced the sintering temperature and promoted the grain growth. The correlations between the dielectric properties and the crystal structure were analyzed through the Rietveld refinement and Raman spectroscopy. The slight shifts of the Raman peaks, corresponding to different vibration modes, were induced by the substitution of Ti⁴⁺ for Zr⁴⁺ and related to the improved quality factor. In general, the sample of MgZr_0.9Ti_0.1Nb₂O₈ sintered at 1320°C for 4 h exhibited promising microwave dielectric properties with an ultra-high Q × f value of 130 123 GHz (at 7.308 GHz, 20°C), which is potential for 5G communication applications.     

A novel spherical-ordered macroporous CuO nanocatalyst for the electrochemical reduction of carbon dioxide

Journal of Applied Electrochemistry - The electrocatalytic reduction of CO2 is a promising research direction in resource utilization and sustainable energy development. However, there is still a...     

Electrochemical investigation of La0.4Sr0.6TiO3 synthesized in air for SOFC application

Journal of Applied Electrochemistry - La-doped titanate materials have been widely investigated as alternative Ni-free anodes for solid oxide fuel cells (SOFCs). In this study, La0.4Sr0.6TiO3 (LST)...