Thermodynamic modeling of the initial microstructural evolution of oxide films grown on bare copper

A thermodynamic model is presented that predicts the initial growth of either a (semi-) coherent crystalline oxide phase or an amorphous oxide phase (with a subsequent amorphous-to-crystalline transition) on a bare metal as function of the substrate orientation, growth temperature and film thickness. The model accounts for possible relaxation of growth stresses by plastic deformation. The direct formation and growth of semi-coherent, crystalline Cu₂O is predicted by application of the model to oxide overgrowth on bare Cu{111}, Cu{100} and Cu{110}. For oxide overgrowths on Cu{111} and Cu{110}, a square grid of misfit dislocations with a dislocation distance of about six Cu₂O unit cells would occur on the basis of the model calculations, which agrees with experimental observations reported for Cu{111} in the literature. On Cu{100} an array of misfit dislocations is formed along the single direction of high lattice mismatch.     

Characterization of copper oxide thin films deposited by the thermal evaporation of cuprous oxide (Cu2O)

Thin films of copper oxide were deposited by thermal evaporation of cuprous oxide (Cu₂O) powder. The substrates were either unheated or heated to a temperature of 300 °C. The films were also annealed in air at a temperature of 500 °C for 3 h. The films were characterized by X-ray photoelectron spectroscopy, X-ray diffraction and UV-visible spectrophotometry. The effects of the substrate temperature and post-deposition annealing on the chemical, structural and optical properties of the films were investigated. As-deposited films on unheated substrates consisted of mixed cupric oxide (CuO) and Cu₂O phases, with a higher concentration of the Cu₂O phase. However, the films deposited on heated substrates and the annealed films were predominantly of the CuO phase.     

Fabrication of transparent conductive films with a sandwich structure composed of ITO/Cu/ITO

New transparent conductive films that had a sandwich structure composed of ITO/Cu/ITO multilayer films were prepared by a conventional RF and DC magnetron sputtering process on a polycarbonate substrate without intentional substrate heating. The thickness of each layer in the ITO/Cu/ITO films was kept constant at 50 nm/5 nm/45 nm. The optoelectrical and structural properties of the films were compared with conventional ITO single-layer films and ITO/Cu/ITO multilayered films. Although both films had identical thickness, 100 nm, the ITO/Cu/ITO films showed a lower resistivity, 3.5 × 10⁻⁴ Ω cm. In optical transmittance measurements, however, the ITO single-layer films showed a higher transmittance of 74% in the wavelength range of 300-800 nm. XRD spectra showed that both the ITO and ITO/Cu/ITO films were amorphous. The figure of merit, φ_TC, reached a maximum of 5.2 × 10⁻⁴ Ω⁻¹ for the ITO/Cu/ITO films, which was higher than the φ_TC of the ITO films (1.6 × 10⁻⁴ Ω⁻¹). The φ_TC results suggested that ITO/Cu/ITO films had better optoelectrical properties than conventional ITO single-layer films.     

Medium frequency magnetron self-sputtering of copper

It is well known that the magnetron self-sustained sputtering (SSS) process can be achieved in the direct current (DC) operation mode (DC-SSS) if certain conditions are fulfilled: high self-sputtering yield of the target material (theoretically Y>1), appropriate magnetron source design, high target power density to ensure high ionization level of the sputtered material. The main disadvantage of the DC-SSS process is the instability related to possibility of an arc formation. The author postulates that magnetron plasma pulsing can minimize this problem.In this paper, voltage and current waveforms of medium frequency (MF) powered magnetron source are analysed. A simple electrical model, explaining dynamics of MF magnetron discharge is presented. The method to achieve MF magnetron SSS process is proposed and experimentally verified. The results of MF magnetron SSS (MF-SSS) process are presented for the first time (to the author's knowledge). The experiments were performed using a planar magnetron source equipped with a copper target of 50 mm in diameter and 6 mm thick. The magnetron source was powered by a resonant (110 kHz) power supply. The target power density during MF-SSS process was about 490 W/cm².     

铜系低变催化剂实验室活性评价方法探讨

在分析一氧化碳铜系低温变换催化剂工业使用条件的基础上,提出了一种实验室条件下的活性评价方法,并对该方法的可靠性进行了验证。结果表明,在实验室条件下采用本方法可客观地评价低变催化剂在工业状况下的主要性能,也基本满足催化剂研发过程中筛选以及催化剂产品定型后正常生产质量控制的要求。     

有机化学教学改革与实践——从小组合作学习谈起

在高校有机化学的教学实践中,以合作小组为基本组织结构单元,学生之间以合作和互动的方式,完成教师分配的目标和任务,教师通过强化学生学习过程的评价、量化学生的学习过程,把过程性评价与终端性评价结合起来。从而有效地实现了学生情感发展与学业成绩提高的统一,认知品质和非认知品质的和谐发展的统一。     

中学化学实验教学绿色化探讨

中学化学实验教学中树立绿色化学实验理念,是贯彻科学发展观,保护学生身体健康,保护环境,节约化学实验资源,提高办学效益,培养学生环境保护观念的重要举措。化学实验教学中可以通过化学实验微型化;化学实验废气、废液、废渣"零排放";以及用多媒体教学演示或仿真化学实验来实现绿色化学实验教学,树立绿色化学实验理念。     

大学有机化学实验教学之我见

从有机实验课教学的重要性、有机实验报告的书写与批改、有机实验开放实验课的开设和有机实验成绩的评定等几方面对有机实验教学发表了自己的看法,并提出了自己的建议。     

铜包铁结合剂在金刚石锯切工具中的应用研究

铁基结合剂金刚石工具是目前石材加工业常用的锯切工具,但是这类工具由于产品性能不稳定等缺点使其应用受到了限制。本文研制了一种铜包铁颗粒,采用化学置换反应在铁粉颗粒表面包覆一层铜粉末,以这种粉末作为铁基金刚石锯切工具的主要成分,同时,对金刚石表面进行盐浴镀钛处理。结果表明,这种铁基金刚石锯切工具烧结温度区间较宽,产品性能对烧结温度不敏感,性能可与铜基结合剂金刚石工具媲美,是一种值得推广的铁基金刚石工具结合剂。     

Scanning microelectrochemical characterization of the anti-corrosion performance of inhibitor films formed by 2-mercaptobenzimidazole on copper

The aim of this work is to explore the applicability of the scanning electrochemical microscope (SECM) to characterize the inhibiting effect of 2-mercaptobenzimidazole against the corrosion of copper. SECM was operated in the feedback mode by using ferrocene-methanol as redox mediator, and the sample was left unbiased at all times. The kinetic changes in the corrosion processes were monitored over time from the Z-approach curves. Furthermore, inhibitor-modified copper samples presenting various surface finishes were imaged by SECM and the scanning vibrating electrode technique (SVET), allowing changes both in the surface activity of metal-inhibitor films and in the extent of corrosion attack to be spatially resolved. Differences in the local electrochemical activity between inhibitor-free and inhibitor-covered areas of the sample were successfully monitored.