Sintering of high-entropy nanoparticles obtained by polyol process: A case study of (La0.2Y0.2Nd0.2Sm0.2Gd0.2)2Ce2O7-δ

High-entropy (HE) ceramics nanoparticles have received much attention due to their interesting properties. However, very limited studies have been conducted on their sintering. Here, we report the sintering behavior of HE A₂B₂O₇ type rare earth oxide nanoparticles obtained by polyol process. HE cerate (HECe) (La_0.2Y_0.2Nd_0.2Sm_0.2Gd_0.2)₂Ce₂O_7-δ is chosen as an exemplary case, which is considered as a good candidate for thermal insulation. HECe nanoparticles with size of 2.6–7.1 nm can be synthesized through polyol process followed by annealing in air at 300–700 °C. HECe nanoparticle compact can be densified by directly sintering at 1500 °C. The sintering temperature could be further decreased using a two-step sintering process, i.e., 1500 °C 5 min-1300 °C 5 h. Our results show that fine particle and abundant oxygen vacancies probably dominate the densification process. By controlling the sintering regime, we can tune the microstructure of HECe ceramics and thermal conductive properties accordingly.     

PMIDA合成中部分液体亚磷酸替代固体亚磷酸的探讨

探讨在IDA.HCl合成PMIDA中,使用部分液体亚磷酸替代部分固体亚磷酸从而降低生产成本的可行性,并确定较佳的替代比例,比较实际生产的经济性.     

金属外壳水三相点容器

水三相点是ITS-90国际温标中最重要的定义固定点,其复现不确定度是传递到整个温标的.目前,通常采用不同的冻制方法在硼硅玻璃或石英水三相点容器内冻制均匀的冰套来复现水三相点.冻制过程中,由于在水三相点容器内生成冰桥,会造成容器的破裂.为了解决此难题,研制了金属外壳水三相点容器,利用高纯水自发相变原理,在液体槽内自动冻制...     

A neutral 2D nanosized molecular square grid: the first vanadium(II)coordination polymer of norfloxacin

The hydrothermal reaction of norfloxacin (H-Norf) with NH₄VO₃ yields an unprecedented neutral nanosized molecular square grid containing a direct coordinate bond between quinololine drug and V(II), V(Norf)₂·2H₂O 1, which is characterized by single X-ray determination and IR spectrum as well as TGA.     

基于标准表法的精密数字测温仪校准方法

参考流量与电学计量领域利用标准表对仪器进行校准的方法,提出一种采用高精度的测温电桥与高稳定性的直流电阻箱组合作为标准装置,校准精密数字测温仪的方法.用此方法对精密数字测温仪进行校准并进行测量不确定度分析,结果表明在-195 ～660℃氛围内,温度示值误差的合成标准不确定度为0.5 ～0.7 mK.此方法采用的标准器准确...     

A two-level parser for patent claim parsing

Patent claim parsing can contribute in many patent-related applications, such as patent search, information extraction, machine translation and summarization. However, patent claim parsing is difficult due to the special structure of patent claims. To overcome this difficulty, the challenges facing the patent claim parsing were first investigated and the peculiarities of claim syntax that obstruct dependency parsing were highlighted. To handle these peculiarities, this study proposes a new two-level parser, in which a conventional parser is imbedded. A patent claim is pre-processed in order to remove peculiarities before passed to the conventional parser. The process is based on a new dependency-based syntax called Independent Claim Segment Dependency Syntax (ICSDS). This two-lever parser has demonstrated promising improvement for patent claim parsing on both effectiveness and efficiency over the conventional parser.     

Tribological properties of polymer/silica composite coatings for microsystems applications

The tribological properties of composite coatings consisting of silica nanoparticles dispersed in either a poly-methylmethacrylate (PMMA) or polystyrene (PS) matrix were assessed. The experiments were conducted using a reciprocating type of micro-tribotester under relatively low normal loads ranging from 5 to 15 mN. Results indicated that the wear resistance of PMMA could be significantly improved by adding silica particles at the cost of increased friction coefficient from 0.27 to 0.4. The effect of silica content on the wear resistance of PS was less apparent. Such outcome was attributed to the difference in the compatibility between silica and the polymer matrix.     

DFT+U study and in-situ TEM investigation of high-entropy titanate pyrochlore (Lu0.25Y0.25Eu0.25Gd0.25)2Ti2O7

High-entropy pyrochlore has become a promising immobilization matrix due to its ability to immobilize multiple nuclides especially for high-level radioactive waste. This work adopts first principle method to analyze the formation possibility of (Lu_0.25Y_0.25Eu_0.25Gd_0.25)₂Ti₂O₇ (HTP-1). By calculating the Gibbs free energy of possible chemical reactions, we predict that the driving force to synthesize HTP-1 is greater than the driving force to form single-component pyrochlore at temperatures above 1225 K. The characterization results show that the HTP-1 sample is successfully prepared by the solid-state reaction at the predicted temperature. To investigate the radiation resistance of HTP-1, the sample is irradiated by 800 keV Kr²⁺ ions, and the microstructure evolution is characterized by in-situ TEM. HTP-1 sample achieves complete amorphous at 0.26 dpa, indicating that its radiation resistance is between Eu₂Ti₂O₇ and Y₂Ti₂O₇, which is proved by the calculation results of x_O48f and antisite defect formation energy.