The growth characteristics of oxide ceramic films formed on AZ31 magnesium alloy with plasma electrolytic oxidation (PEO) technique in alkaline silicate solution were investigated. The composition, structure and morph...The growth characteristics of oxide ceramic films formed on AZ31 magnesium alloy with plasma electrolytic oxidation (PEO) technique in alkaline silicate solution were investigated. The composition, structure and morphology of the coatings were detected by energy dispersive X-ray spectroscope and scanning electron microscope. The amount of dissolved magnesium in the electrolytes during PEO process was measured by atomic absorption spectrometry. The results indicated that the growth process of PEO films had three stages when applied with constant voltage mode. In the first stage, the growth rate of PEO films was low, and concentrations of elements O, Mg and Si varied slightly. After sparking occurred (the second stage), the PEO films showed higher growth rate due to the high transfer rate of ions and electrons, and the existence of plasma reactions. When the growth rate tended to maintain stable with time, the third stage happened. PEO films exhibited different uniform and pitting-corrosion characteristics in different reaction stages. The films formed at 300 V for 30 min performed best corrosion resistance and the phase of ceramic films was mainly composed of MgSiO3 and forsterite Mg2SiO4.展开更多
Morphological structure and growth process of LbL nanostructured films from nickel tetrasulfonated phthalocyanine (NiTsPc) alternated with polyallylamine hydrochloride (PAH) were investigated. The experimental results...Morphological structure and growth process of LbL nanostructured films from nickel tetrasulfonated phthalocyanine (NiTsPc) alternated with polyallylamine hydrochloride (PAH) were investigated. The experimental results of UV-visible adsorption kinetics (modeled by Johnson-Mehl-Avrami functions) and AFM images analyzes suggested that the surface morphology structure of films is formed by rod-shaped aggregates produced by a two-step growth process: nucleation and diffusion-limited growth.展开更多
YBa_2Cu_3O_（7-δ）（YBCO） films were deposited on（100）-oriented LaAlO_3（LAO） single crystal substrates by the dip-coating process using low-fluorine solution.Their microstructures were characterized with the aid...YBa_2Cu_3O_（7-δ）（YBCO） films were deposited on（100）-oriented LaAlO_3（LAO） single crystal substrates by the dip-coating process using low-fluorine solution.Their microstructures were characterized with the aid of X-ray diffractometry,scanning electron microscopy and high-resolution transmission electron microscopy.Their superconducting properties were measured by the standard four-probe method.The experiment results show that the film obtained under high enough humidity conditions exhibits better c-axis texture and superconducting properties than the film under a relatively low humidity conditions.Based on the classical nucleation and chemical reaction thermodynamics theory, the underlying crystalline and growth mechanisms of YBCO films under certain humidity conditions are explained in combination with our experimental results.It is suggested that the unreacted intermediate phases such as BaF_2 and CuO aggregated in the YBCO grain boundary will cause lattice distortion in the YBCO matrix and further induce the formation of a-axis oriented YBCO grains as crystallization proceeds.Therefore,it is believed that the relative content of water vapor within the heat-treatment atmosphere plays quite an important role in the preparation of c-axis oriented YBCO film with good superconducting properties.展开更多
以硅烷和氨气分别做为硅源和氮源,以高纯氮气为载气,采用热壁式管式反应炉,通过低压化学气相沉积(low pressure chemical vapor deposition,LPCVD)技术制备了氮化硅薄膜(SiN_x)。借助椭圆偏振仪研究了SiN_x薄膜的生长动力学,通过Fourie...以硅烷和氨气分别做为硅源和氮源,以高纯氮气为载气,采用热壁式管式反应炉,通过低压化学气相沉积(low pressure chemical vapor deposition,LPCVD)技术制备了氮化硅薄膜(SiN_x)。借助椭圆偏振仪研究了SiN_x薄膜的生长动力学,通过Fourier红外光谱和X光电子能谱表征了SiN_x薄膜的性质,并利用原子力显微镜观察了SiN_x薄膜的微观形貌。在其它工艺条件相同的情况下,SiN_x薄膜的生长速率随着工作压力的增大单调增加,原料气中氨气与硅烷的流量之比(R)对薄膜的生长速率有相反的影响。随着反应温度的升高,沉积速率逐渐增加,在840℃附近达到最大,随后迅速降低。当R<2时获得富Si的SiN_x薄膜(x<1.33);当R>4时获得近化学计量(z≈1.33)的SiN_x薄膜。展开更多
用动力学晶格蒙特卡洛模型(Kinetic Lattice Monte Carlo,KLMC)模拟Cu薄膜的生长过程,讨论了基底温度、沉积原子数、单原子最大迁移步数和原子相互作用范围等参数对薄膜表面形貌的影响,并与实验结果进行了比较。结果表明:基底温度升高...用动力学晶格蒙特卡洛模型(Kinetic Lattice Monte Carlo,KLMC)模拟Cu薄膜的生长过程,讨论了基底温度、沉积原子数、单原子最大迁移步数和原子相互作用范围等参数对薄膜表面形貌的影响,并与实验结果进行了比较。结果表明:基底温度升高或沉积原子数增加时,沉积在基底上的原子逐步由众多各自独立的离散型分布向聚集状态过渡形成团簇,并且温度越低,团簇越趋于分散生长。当最大迁移步数减小或相互作用范围增大时,团簇亦趋于分散生长。展开更多
基金Supported by the Guangdong Province Science and Technology Plan Project (No.2005B50101001)
文摘The growth characteristics of oxide ceramic films formed on AZ31 magnesium alloy with plasma electrolytic oxidation (PEO) technique in alkaline silicate solution were investigated. The composition, structure and morphology of the coatings were detected by energy dispersive X-ray spectroscope and scanning electron microscope. The amount of dissolved magnesium in the electrolytes during PEO process was measured by atomic absorption spectrometry. The results indicated that the growth process of PEO films had three stages when applied with constant voltage mode. In the first stage, the growth rate of PEO films was low, and concentrations of elements O, Mg and Si varied slightly. After sparking occurred (the second stage), the PEO films showed higher growth rate due to the high transfer rate of ions and electrons, and the existence of plasma reactions. When the growth rate tended to maintain stable with time, the third stage happened. PEO films exhibited different uniform and pitting-corrosion characteristics in different reaction stages. The films formed at 300 V for 30 min performed best corrosion resistance and the phase of ceramic films was mainly composed of MgSiO3 and forsterite Mg2SiO4.
文摘Morphological structure and growth process of LbL nanostructured films from nickel tetrasulfonated phthalocyanine (NiTsPc) alternated with polyallylamine hydrochloride (PAH) were investigated. The experimental results of UV-visible adsorption kinetics (modeled by Johnson-Mehl-Avrami functions) and AFM images analyzes suggested that the surface morphology structure of films is formed by rod-shaped aggregates produced by a two-step growth process: nucleation and diffusion-limited growth.
基金Project supported by the National Natural Science Foundation of China(No.50772088)the Doctoral Fund of Ministry of Education of China(No.20096118110002).
文摘YBa_2Cu_3O_（7-δ）（YBCO） films were deposited on（100）-oriented LaAlO_3（LAO） single crystal substrates by the dip-coating process using low-fluorine solution.Their microstructures were characterized with the aid of X-ray diffractometry,scanning electron microscopy and high-resolution transmission electron microscopy.Their superconducting properties were measured by the standard four-probe method.The experiment results show that the film obtained under high enough humidity conditions exhibits better c-axis texture and superconducting properties than the film under a relatively low humidity conditions.Based on the classical nucleation and chemical reaction thermodynamics theory, the underlying crystalline and growth mechanisms of YBCO films under certain humidity conditions are explained in combination with our experimental results.It is suggested that the unreacted intermediate phases such as BaF_2 and CuO aggregated in the YBCO grain boundary will cause lattice distortion in the YBCO matrix and further induce the formation of a-axis oriented YBCO grains as crystallization proceeds.Therefore,it is believed that the relative content of water vapor within the heat-treatment atmosphere plays quite an important role in the preparation of c-axis oriented YBCO film with good superconducting properties.
文摘以硅烷和氨气分别做为硅源和氮源,以高纯氮气为载气,采用热壁式管式反应炉,通过低压化学气相沉积(low pressure chemical vapor deposition,LPCVD)技术制备了氮化硅薄膜(SiN_x)。借助椭圆偏振仪研究了SiN_x薄膜的生长动力学,通过Fourier红外光谱和X光电子能谱表征了SiN_x薄膜的性质,并利用原子力显微镜观察了SiN_x薄膜的微观形貌。在其它工艺条件相同的情况下,SiN_x薄膜的生长速率随着工作压力的增大单调增加,原料气中氨气与硅烷的流量之比(R)对薄膜的生长速率有相反的影响。随着反应温度的升高,沉积速率逐渐增加,在840℃附近达到最大,随后迅速降低。当R<2时获得富Si的SiN_x薄膜(x<1.33);当R>4时获得近化学计量(z≈1.33)的SiN_x薄膜。
文摘用动力学晶格蒙特卡洛模型(Kinetic Lattice Monte Carlo,KLMC)模拟Cu薄膜的生长过程,讨论了基底温度、沉积原子数、单原子最大迁移步数和原子相互作用范围等参数对薄膜表面形貌的影响,并与实验结果进行了比较。结果表明:基底温度升高或沉积原子数增加时,沉积在基底上的原子逐步由众多各自独立的离散型分布向聚集状态过渡形成团簇,并且温度越低,团簇越趋于分散生长。当最大迁移步数减小或相互作用范围增大时,团簇亦趋于分散生长。
