ZnO films with c -axis parallel to the substrate are reported.ZnO films are synthesized by solid-source chemical vapor deposition,a novel CVD technique,using zinc acetate dihydrate (solid) as the source material.The p...ZnO films with c -axis parallel to the substrate are reported.ZnO films are synthesized by solid-source chemical vapor deposition,a novel CVD technique,using zinc acetate dihydrate (solid) as the source material.The properties are characterized by X-ray diffraction,atomic force microscopy and transmission spectra.The parallel oriented ZnO films with mixed orientation for (100) and (110) planes are achieved on glass at the substrate temperature of 200℃ and the source temperature of 280℃,and a qualitative explanation is given for the forming of the mixed orientation.AFM images show that the surface is somewhat rough for the parallel oriented ZnO films.The transmission spectrum exhibits a high transmittance of about 85% in the visible region and shows an optical band gap about 3.25eV at room temperature.展开更多
Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology develop...Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick＇s model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.展开更多
Pulsed electrohydrodynamic printing （EHDP） is used to fabricate conductive silver patterns with micrometer resolution. The silver ink pendant experiences swelling, pulsation, and ejection under an applied pulse volt...Pulsed electrohydrodynamic printing （EHDP） is used to fabricate conductive silver patterns with micrometer resolution. The silver ink pendant experiences swelling, pulsation, and ejection under an applied pulse voltage of 20 Hz. The droplet deposi- tion frequency is equal to the applied voltage frequency so that the EHDP can deposit silver ink on demand. A low applied voltage favors uniform and non-scattering silver patterns while a high applied voltage results in ink scattering. Discrete drop- lets with 45-55 gm in diameter and continuous tracks with 60 gm in width are generated by using a ll0-i.tm-cailber nozzle. The feature size of deposited patterns is about half of the nozzle caliber, and a finer resolution can be achieved with the intro- duction of smaller nozzle calibers. Furthermore, the appropriate curing condition is investigated for sufficient combustion of ink solvent. The minimum resistivity of 3.3 gf~ cm is demonstrated for a continuous track cured at 200~C for 10 min. Eventu- ally, several passive electrical components, such as coated resistors, interdigitated capacitors （6 pF）, and spiral inductors （0.6 gH）, are successfully fabricated.展开更多
文摘ZnO films with c -axis parallel to the substrate are reported.ZnO films are synthesized by solid-source chemical vapor deposition,a novel CVD technique,using zinc acetate dihydrate (solid) as the source material.The properties are characterized by X-ray diffraction,atomic force microscopy and transmission spectra.The parallel oriented ZnO films with mixed orientation for (100) and (110) planes are achieved on glass at the substrate temperature of 200℃ and the source temperature of 280℃,and a qualitative explanation is given for the forming of the mixed orientation.AFM images show that the surface is somewhat rough for the parallel oriented ZnO films.The transmission spectrum exhibits a high transmittance of about 85% in the visible region and shows an optical band gap about 3.25eV at room temperature.
基金This work was supported by the National Basic Research Program of China （No.2012CB215405）, the National Natural Science Foundation of China （No.11374272）, and the Specialized Research Fund for the Doctoral Program of Higher Education （No.20123402110064）.
文摘Internal reformation of low steam methane fuel is important for the high efficiency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick＇s model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.
基金supported by the National Natural Science Foundation of China (Grant No. 51035002)the Key Project of Chinese Ministry of Edu-cation (Grant No. 708055)the Fundamental Research Funds for the Central Universities (Grant No. 2010121039)
文摘Pulsed electrohydrodynamic printing （EHDP） is used to fabricate conductive silver patterns with micrometer resolution. The silver ink pendant experiences swelling, pulsation, and ejection under an applied pulse voltage of 20 Hz. The droplet deposi- tion frequency is equal to the applied voltage frequency so that the EHDP can deposit silver ink on demand. A low applied voltage favors uniform and non-scattering silver patterns while a high applied voltage results in ink scattering. Discrete drop- lets with 45-55 gm in diameter and continuous tracks with 60 gm in width are generated by using a ll0-i.tm-cailber nozzle. The feature size of deposited patterns is about half of the nozzle caliber, and a finer resolution can be achieved with the intro- duction of smaller nozzle calibers. Furthermore, the appropriate curing condition is investigated for sufficient combustion of ink solvent. The minimum resistivity of 3.3 gf~ cm is demonstrated for a continuous track cured at 200~C for 10 min. Eventu- ally, several passive electrical components, such as coated resistors, interdigitated capacitors （6 pF）, and spiral inductors （0.6 gH）, are successfully fabricated.
