Papers by Keyword: NiO Thin Film

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Authors: Min Ren Zhang, Hong Hui Lai, Yi Mu Lee, Chun Hung Lai, Yi Der Wu, Hsi Wen Yang
Abstract: N-type ZnO nanorod arrays and p-type NiO thin films have been prepared on the ITO substrates by chemical bath deposition (CBD) and sol-gel spin coating method, respectively, then followed by thermal treatment at 400 °C for 1 h. The ZnO nanorod arrays have length of around 1.5 μm and diameter of around 55 nm; the thickness of the NiO film is around 340 nm with average grain size of 22 nm. The sensing properties of the n-type ZnO and the p-type NiO for the detection of aqueous ethanol solutions at room temperature are investigated using electrical impedance spectroscopy (EIS). The EIS results reveal that the series resistance (Rs) is as low as 27 Ω; the charge-transfer resistance (Rct) remarkably contributes to the sensing properties of the ethanol sensor, and decreases with a decreasing concentration (99.5%-1%) from 17.0 kΩ to 2.6 kΩ. An equivalent circuit with capacitors and resistors was developed to investigate the conduction process according to complex impedance (Nyquist) diagrams. In low concentration range, the electron conduction process is dominated by the Rct and a constant phase element (CPE); however, in high concentration ethanol solution, the conduction process is dominated by polarization and decomposition of the absorbed water with larger Rct observed. Moreover, I-V measurements were carried out to evaluate the sensitivity of n-ZnO and p-NiO nanostructures at room temperature.
127
Authors: Ya Ru Zhang, Bo Ping Zhang, Yan Dong, Jing Feng Li
Abstract: Li and Ti co-doped NiO thin films with 200 nm in thickness were deposited onto Pt/Ti/SiO2/ Si(100) substrates using a sol-gel spin-coating method. The effect of Ti doping content on microstructure and dielectric properties of Li0.10TixNi0.90-xO (x=5-20mol%) thin films was investigated. XRD results showed that all the Li0.10TixNi0.90-xO thin films consisted of a mixture of NiO, Li2NiO2 and NiTiO3 oxides. The intensities of the diffraction peaks for the NiTiO3 phase increased and those for NiO decreased with increasing Ti content, suggesting that a part of NiO phase combined with Ti to form NiTiO3 phase. The dielectric constants of all the Li0.10TixNi0.90-xO thin films at 102 Hz at room temperature ranged from 200 to 400 and increased with increasing Ti content. The frequency stability of the dielectric constant for the Li0.10TixNi0.90-xO thin films was also improved greatly with increasing Ti content.
2639
Authors: Ji Ne Zhu, Sheng Li Zhao, Jiu Ba Wen, Zhao Yang Wu
Abstract: The thermal decomposition behavior of gel precursor, the structure, morphology and electrochemical properties of NiO thin films prepared by sol-gel process were characterized by thermogravimetric/differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and constant current charge-discharge techniques. The results show that the gel precursor completely decomposes and gradually forms the nanocrystalline NiO at 450°C during the sintering. The NiO thin film is smooth, uniform and free of cracks drying at 200°C as pretreatment and sintering at a low temperature rise rate. The structure of NiO films sintered at 500°C for 2h becomes integrity, whose discharge capacity after 20 cycles remains at 714mAh/g. It is promising to be used in Li-ion battery for great initial specific capacity and well cycle performances.
2487
Authors: X.H. Xia, J.P. Tu, J. Zhang, X.L. Wang
Abstract: NiO thin films were prepared on ITO glass by a modified sol-gel method in combination with a following annealing process. The XRD results show that the film annealed at 280 °C is amorphous, while the films annealed at and above 300 °C are cubic NiO phase. The electrochromic performances of the annealed films were characterized by means of UV–vis spectroscopy and cyclic voltammetry (CV) measurements. The film annealed at 280 °C exhibits a noticeable electrochromism with a variation of transmittance up to 76 % at 550 nm. The cyclic voltammetry (CV) measurements reveal that the film annealed at higher temperature has better electrochemical reversibility.
625
Authors: Cui Hua Zhao, Bo Ping Zhang, Yong Liu, Song Jie Li
Abstract: LixTixNi1-2xO (x =0, 10 and 20 at. %) thin films with 200 nm in thickness were deposited on Pt/Ti/SiO2/Si (100) by a sol-gel spin-coating method. All samples have a uniform microstructure. The grain sizes grew from 100 nm to 300 nm by co-doping Li and Ti. The LiTiNiO thin films consist of NiO, NiTiO3 and Li2NiO2, while the Li-free thin films consist of NiO, NiTiO3 and NiTi0.99O3. The dielectric properties of the LiTiNiO thin films improved obviously by co-doping Li and Ti, but excess Li increases the amount of Li2NiO2 phase and decreases the dielectric properties. The dielectric constants at 100 Hz for the Li0.1Ti0.1Ni0.8O and Li0.2Ti0.2Ni0.6O thin films are 506 and 388 respectively. Appropriate co-doping contents of Li and Ti are important to obtain a high dielectric property.
1817
Authors: Sheng Li Zhao, Ji Ne Zhu, Zhao Yang Wu
Abstract: The NiO thin film was deposited on the stainless and single crystal Si substrate by the dip-coating combined with thermal treatment. Thermal decomposition behavior of gel precursor, the structure, morphology and electrochemical properties of NiO thin film were characterized by TG-DSC, XRD, SEM, cyclic voltammetry and the constant current charge/discharge technology. The results show that the gel completely decomposes at 430°C to form the nanocrystalline NiO gradually and its crystal structure becomes integrity and particles largen as the increasing of the sintering temperature. The NiO film sintered at 600°C exhibits smooth surface, uniform, compact and free of cracks. At the cut-off voltage of 0-3V and the current density of 0.01 mA/cm2, its first discharge special capacity is 1285mAh/g and remains 650mAh/g after 300 cycles. In addition, the special capacity of NiO thin film still remains above 300mAh/g at large current density of 0.04 mAh/g after 300cycles exhibiting excellent electrochemical performance.
1073
Authors: Manisha Tyagi, Monika Tomar, Vinay Gupta
Abstract: The influence of substrate temperature on the UV-Visible-near-IR optical properties, namely the band gap, the Urbach energy and the refractive index of NiO thin films deposited by RF sputtering has been investigated. The optical band gap of thin films showed the blue-shift in the transmission spectra with increase in the substrate temperature which is related to variation in carrier concentration of the deposited films. Urbach energy (EU) values indicate that the films deposited at 400 oC substrate temperature show least structural disorder. The refractive index of the films is found to decrease continuously with increase in the substrate temperature at all photon energies in the visible and near-IR region, and is attributed to the decreasing packing density of the films. Introduction
103
Authors: Shen Li Zhao, Ji Ne Zhu, J.B. Wen, Zhao Yang Wu
Abstract: The NiO thin film was deposited on the stainless steel substrate by spin-coating compared with thermal treatment technique. Thermal decomposition behavior of gel precursor, the structure, morphology and electrochemical properties of NiO thin film were characterized by thermogravimetric/differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and constant current charge-discharge techniques. The results show that the stable sol is synthesized by nickel acetate and PAA. The gel precursor completely decomposes and gradually forms the nanocrystalline NiO at 450°C during the sintering. The crystal structure of NiO films become more integrity and particles large with the increasing of sintering temperature. The morphology and structure of the NiO thin film sintered at 500°C for 2h is perfect and exhibits high discharge specific capacity and well cycle performance whose initial and stable discharge capacity after 20 cycles are 1147.5mAh/g and 741mAh/g , respectively.
729
Authors: Yu Cai, Zhao Yang Wu, Sheng Li Zhao, Ji Ne Zhu
Abstract: The variation of impedance property during the 1st charge/discharge course was investigated by electrochemical impedance spectroscopy (EIS). The results show that the proposed equivalent circuit of RS(Qdl(RCtZW))(QSEIRSEI) perfectly simulating the EIS measurement data and all the errors less than 5% can reasonably explain the course of the reaction between Li and NiO electrode. The SEI film which distinctly influences the electrochemical performance of lithium ion battery is free at open circuit voltage. It begins to slowly grow at polarization voltage of 1.5V and completely forms at 0.3V in the 1st discharge. To react further with NiO, the Li+ must pass through SEI film and generate the fine grains Ni and amorphous Li2O matrix. SEI film partially decomposes and the NiO and Li are formed by reversible reaction of Ni and Li2O in the charge course.
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