The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Masaharu Shiratani - One of the best experts on this subject based on the ideXlab platform.
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highly conducting and very thin zno al films with zno buffer layer fabricated by solid Phase crystallization from Amorphous Phase
Applied Physics Express, 2011Co-Authors: Naho Itagaki, Kazunari Kuwahara, Kenta Nakahara, Daisuke Yamashita, Giichiro Uchida, Kazunori Koga, Masaharu ShirataniAbstract:We propose a novel method of oxide crystal growth via atomic-additive mediated amorphization. By utilizing this method, solid-Phase crystallization (SPC) of ZnO from Amorphous Phase has been successfully demonstrated via nitrogen atom mediation. The resultant SPC-ZnO films are highly orientated and the crystallinity is higher than that of the films prepared by conventional sputtering. By using the SPC-ZnO as a buffer layer, the resistivity of ZnO:Al (AZO) films is drastically decreased. 20-nm-thick AZO films with a resistivity of 5×10-4 Ω cm and an optical transmittance higher than 80% in a wide wavelength range of 400–2500 nm have been obtained.
Ikufumi Katayama - One of the best experts on this subject based on the ideXlab platform.
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ultrafast crystalline to Amorphous Phase transition in ge2sb2te5 chalcogenide alloy thin film using single shot imaging spectroscopy
Applied Physics Letters, 2014Co-Authors: Jun Takeda, Wataru Oba, Y Minami, Toshiharu Saiki, Ikufumi KatayamaAbstract:We have observed an irreversible ultrafast crystalline-to-Amorphous Phase transition in Ge2Sb2Te5 chalcogenide alloy thin film using broadband single-shot imaging spectroscopy. The absorbance change that accompanied the ultrafast amorphization was measured via single-shot detection even for laser fluences above the critical value, where a permanent amorphized mark was formed. The observed rise time to reach the amorphization was found to be ∼130–200 fs, which was in good agreement with the half period of the A1 phonon frequency in the octahedral GeTe6 structure. This result strongly suggests that the ultrafast amorphization can be attributed to the rearrangement of Ge atoms from an octahedral structure to a tetrahedral structure. Finally, based on the dependence of the absorbance change on the laser fluence, the stability of the photoinduced Amorphous Phase is discussed.
J M Cadogan - One of the best experts on this subject based on the ideXlab platform.
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effect of co or ge doping on the intergranular magnetic coupling in nanocrystalline fe89zr7b3cu1
Journal of Applied Physics, 2002Co-Authors: K Suzuki, J M Cadogan, J W Cochrane, X Y Xiong, K HonoAbstract:The Curie temperature of the residual Amorphous Phase in nanocrystalline Fe89Zr7B3Cu1 is enhanced by Ge addition and the magnetic hardening at elevated temperatures is suppressed. On the other hand, the addition of Co brings about severe deterioration of the magnetic softness for the same alloy presumably because of the induced anisotropy effect. The Mossbauer and atom probe field ion microscopy analyses indicate that Ge-induced magnetic softening is due to the preferential enrichment of Ge into the residual Amorphous Phase which results in an enhancement of the exchange stiffness in the intergranular region.
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the effect of the spontaneous magnetization in the grain boundary region on the magnetic softness of nanocrystalline materials
Journal of Applied Physics, 1999Co-Authors: Kiyonori Suzuki, J M CadoganAbstract:The relationship between the mean hyperfine field of the residual intergranular Amorphous Phase 〈Bhf〉 and the coercivity Hc in various nanocrystalline soft magnetic samples has been investigated in order to clarify the effect of the spontaneous magnetization in the grain boundary region on their magnetic softness. Nanocrystalline samples with various 〈Bhf〉 values were prepared by annealing an Amorphous Fe91Zr7B2 precursor for periods of 60 s–108 ks, at temperatures of 823–973 K. Hc shows a clear tendency to decrease with increasing 〈Bhf〉 or decreasing volume fraction of the residual Amorphous Phase. These effects of the residual Amorphous Phase on Hc are well understood within the framework of our extended two-Phase random anisotropy model where both the exchange stiffness constant and volume fraction of the grain boundary Phase are relevant to the exchange correlation length. Our results indicate that the exchange stiffness constant of the intergranular region varies as the square of the spontaneous magn...
Naho Itagaki - One of the best experts on this subject based on the ideXlab platform.
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highly conducting and very thin zno al films with zno buffer layer fabricated by solid Phase crystallization from Amorphous Phase
Applied Physics Express, 2011Co-Authors: Naho Itagaki, Kazunari Kuwahara, Kenta Nakahara, Daisuke Yamashita, Giichiro Uchida, Kazunori Koga, Masaharu ShirataniAbstract:We propose a novel method of oxide crystal growth via atomic-additive mediated amorphization. By utilizing this method, solid-Phase crystallization (SPC) of ZnO from Amorphous Phase has been successfully demonstrated via nitrogen atom mediation. The resultant SPC-ZnO films are highly orientated and the crystallinity is higher than that of the films prepared by conventional sputtering. By using the SPC-ZnO as a buffer layer, the resistivity of ZnO:Al (AZO) films is drastically decreased. 20-nm-thick AZO films with a resistivity of 5×10-4 Ω cm and an optical transmittance higher than 80% in a wide wavelength range of 400–2500 nm have been obtained.
Xiaoyu Zhao - One of the best experts on this subject based on the ideXlab platform.
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characterization thermal stability and solid state Phase transition behaviors of gestodene polymorphs and Amorphous Phase
Journal of Thermal Analysis and Calorimetry, 2017Co-Authors: Liyu Wang, Xianchao Li, Yanfei Wang, Libin Yang, Xiaoyu ZhaoAbstract:In the current work, a systematic investigation on the thermal behavior of gestodene was carried out to understand temperature induced solid-state transitions between its polymorphs and Amorphous Phase. The focus was on polymorph identification, thermal stability analysis, and the nature of the Phase transitions. These characteristics were compared to the complexity of the Phase transitions, studied by differential scanning calorimetry (DSC) and variable temperature X-ray powder diffraction (VT-XRD) techniques. DSC studies indicated that the form II was enantiotropically related to form I, which melted at about 470 K. The temperature of polymorphic transition was 309 K, and form II was the more stable form between room temperature and the transition temperature. A schematic Gibbs free energy-temperature diagram was subsequently constructed to describe the thermal stability of the two forms. Amorphous Phase converted exothermically to form I at 368 K on heating and was shown by VT-XRD to be accompanied by diffraction pattern changes. In addition, the crystallization kinetics studied by DSC heating technique followed by analysis using the Kissinger–Akahira–Sunose (KAS) method where values of apparent activation energy (E a) were estimated as a function of extent of conversion (α). The variations in E a with α on kinetic analysis from α = 0.10 to 0.88 for the Amorphous to form I conversion suggested more complex processes, possibly liquid–solid and solid–solid transformations prior to formation of the form I.
