The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform

Mutian Chen - One of the best experts on this subject based on the ideXlab platform.

  • tio2 nanoparticle induced space charge decay in thermal aged transformer oil
    Applied Physics Letters, 2013
    Co-Authors: Yuzhen Lv, Yuxiang Zhong, Yuefan Du, Bo Qi, Chengrong Li, Mutian Chen
    Abstract:

    TiO2 nanoparticle with good dispersibility and stability in transformer oil was prepared and used to modify insulating property of aged oil. It was found that space charge decay rate in the modified aged oil can be significantly enhanced to 1.57 times of that in the aged oil at first 8 s after polarization voltage was removed. The results of Trap characteristics reveal that the modification of nanoparticle can not only greatly lower the Shallow Trap energy level in the aged oil but also increase the Trap density, resulting in improved charge transportation via Trapping and de-Trapping process in Shallower Traps.

  • Effect of electron Shallow Trap on breakdown performance of transformer oil-based nanofluids
    Journal of Applied Physics, 2011
    Co-Authors: Mutian Chen, Jianquan Zhou, You Zhou
    Abstract:

    Transformer oil-based nanofluids with TiO2 semiconductive nanoparticles exhibit substantially higher AC and positive impulse breakdown voltage levels than that of pure transformer oils. Thermally stimulated current method (TSC) and pulse electroacoustic technique (PEA) have been used to measure charge Trap and transportation characteristics of pure oils and nanofluids. It is found that electron Shallow Trap density and charge decay rate are greatly increased in nanofluids, i.e., fast electrons may be converted to slow electrons by electron Trapping and de-Trapping in Shallow Traps of nanofluids, resulting in improved breakdown performance compared to that of pure oil.

David M. Savory - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Formate Adsorption and Protons on Shallow Trap Infrared Absorption (STIRA) of Anatase TiO2 During Photocatalysis
    The Journal of Physical Chemistry C, 2013
    Co-Authors: David M. Savory, A. James Mcquillan
    Abstract:

    ATR-IR spectroscopy has been used to probe the spectral changes resulting from UV irradiation of thin particulate films of anatase TiO2 under aqueous anoxic conditions. Irradiation under circumneutral solutions removed adsorbed impurities and produced a transient broad IR absorption peaking at ∼880 cm–1 that has been attributed to excitations associated with Shallow electron Traps. This Shallow Trap IR absorption (STIRA) was long-lived under acidic conditions with peak absorbance rising with decreasing pH. Formate was used as a hole scavenger to probe the impact of hole removal on the electron Trapping processes. The adsorption of formate to anatase TiO2 was investigated in the absence of UV irradiation with the spectra showing a mixture of inner- and outer-sphere adsorbed species. UV irradiation of anatase films in the presence of formate at low concentrations enhanced STIRA intensity substantially. The STIRA scaled with TiO2 mass was more pronounced from larger crystallite anatase and was sensitive to [...

  • Shallow electron Trap interfacial water and outer sphere adsorbed oxalate ir absorptions correlate during uv irradiation of photocatalytic tio2 films in aqueous solution
    Journal of Physical Chemistry C, 2011
    Co-Authors: David M. Savory, David S Warren, James A Mcquillan
    Abstract:

    IR spectroscopic analysis of thin particle film anatase-containing TiO2 systems during UV irradiation and when immersed in acidic anoxic aqueous solution reveals a striking broad asymmetric IR peak ∼880 cm−1 extending to over 2000 cm−1, which has been previously attributed to electron excitations from a Shallow Trap level. The observations of this broad IR absorption in quasi-vacuum conditions or in aqueous solutions appear contradictory but are explained by the absence of electron scavengers or hole scavengers, respectively. The broad IR absorption associated with the Shallow electron Trap becomes more pronounced with a decrease in pH from 5 to 2 and is greatly enhanced in the presence of adsorbed oxalate. Oxalate ion adsorption/desorption kinetics has been followed with IR spectroscopy during UV irradiation to show that the Shallow Trap IR absorption correlates with that of outer-sphere adsorbed oxalate acting as a hole scavenger. The IR spectra indicate the involvement of interfacial water in the elect...

Binghui Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Performance and stability of amorphous InGaZnO thin film transistors with a designed device structure
    Journal of Applied Physics, 2011
    Co-Authors: Jie Zhang, L. Gong, Jun Huang, Yinzhu Zhang, L. X. Chen, Binghui Zhao
    Abstract:

    We propose a specifically designed structure to fabricate thin-film transistors using amorphous indium-gallium-zinc-oxide (a-IGZO) films as the active channel layers. The I-shaped gate electrode is employed to define the channel width, reducing overlaps between the gate and source/drain electrodes. The devices with such a structure exhibit acceptable electrical performance and stability after annealing treatment. The XPS data show that the as-deposited a-IGZO film has not a very dense structure that may induce Shallow Traps. A Shallow Trap model is proposed to explain the large threshold voltage shifts of the as-deposited device. Annealing treatment can eliminate these Shallow Traps and improve the device stability.

J G Gies - One of the best experts on this subject based on the ideXlab platform.

  • Charge transfer mechanisms between some Shallow-Trap centres involved in the photochromism of Bi12GeO20
    Optical Materials, 2000
    Co-Authors: H Marquet, J C Merle, J G Gies
    Abstract:

    Abstract Charge transfers between Traps in undoped Bi12GeO20 (BGO) crystals have been investigated so as to complete our previous studies concerning the mechanism of the photochromism in these crystals. Thermally stimulated current measurements as a function of both the temperature at which the crystals are photoexcited and the density of energy used to photoexcite them were carried out between 80 and 350 K. The results show that the detected electron Traps, due to their behaviour, can be schematically divided into two families: the Shallower ones and the deeper ones. Two of the most important Traps among the latter which play the role of electron reservoirs for the fundamental state of the photochromic transitions in the visible spectral range are populated via the former. Hence, the Shallower Traps act as precursory levels to the filling of the deeper Traps.

  • the role of some Shallow Trap centres in the photochromism of bi12geo20
    EPL, 1999
    Co-Authors: H Marquet, J G Gies, J C Merle
    Abstract:

    A close correlation between thermally stimulated conductivity and thermally bleached photochromism experiments allows us to propose a charge transfer mechanism: free electrons are generated by an appropriate illumination, which either ionizes deep donor centres or creates band-to-band transitions. These electrons are Trapped on Shallow levels. Three of them act as reservoirs and in turn populate a deeper level which constitutes the fundamental state of the photochromic transitions. The model well explains the variation of the magnitude of the photochromism under variable optical excitation and de-excitation as well as its thermal stability.

R W Hellwarth - One of the best experts on this subject based on the ideXlab platform.