Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate （DOP） as milling medium without solvent. The obtained mixture could be directly mixed with poly（vinyl chloride）...Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate （DOP） as milling medium without solvent. The obtained mixture could be directly mixed with poly（vinyl chloride） （PVC） for melt-forming, with DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 ×10 6 Ω/ at 1 wt% carbon additive, significantly lower than approx. 7 wt% of raw graphite required for achieving the same level. This value is low enough for practical antistatic criterion of 3 × 10 8 Ω/ . The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite.展开更多
基于机械剥离方法,即通过胶带反复剥离高定向热解石墨,制备得到少层石墨烯,并将其作为可饱和吸收体实现了被动谐波锁模掺铒光纤激光器。在抽运功率约135 m W时,获得了中心波长1568.3 nm,脉冲宽度1.82 ps,3 d B带宽1.7 nm,重复频率1.646 ...基于机械剥离方法,即通过胶带反复剥离高定向热解石墨,制备得到少层石墨烯,并将其作为可饱和吸收体实现了被动谐波锁模掺铒光纤激光器。在抽运功率约135 m W时,获得了中心波长1568.3 nm,脉冲宽度1.82 ps,3 d B带宽1.7 nm,重复频率1.646 MHz的基频锁模激光输出。通过增加抽运功率和调节腔内偏振,可以获得谐波锁模,谐波阶数最高达到基频的47阶(77.36 MHz)。同时,研究了不同阶谐波锁模时,输出功率、脉冲宽度和单脉冲能量的变化。展开更多
Mechanical exfoliation is a widely used method to isolate high quality graphene layers from bulk graphite. In our recent experiments, some ordered microstructures, consisting of a periodic alternation of kinks and str...Mechanical exfoliation is a widely used method to isolate high quality graphene layers from bulk graphite. In our recent experiments, some ordered microstructures, consisting of a periodic alternation of kinks and stripes, were observed in thin graphite flakes that were mechanically peeled from highly oriented pyrolytic graphite. In this paper, a theoretical model is presented to attribute the formation of such ordered structures to the alternation of two mechanical processes during the exfoliation： （1） peeling of a graphite flake and （2） mechanical buckling of the flake being sub- jected to bending. In this model, the width of the stripes L is determined by thickness h of the flakes, surface energy Y, and critical buckling strain ecr. Using some appropriate values of y and ecr that are within the ranges determined by other inde- pendent experiments and simulations, the predicted relations between the stripe width and the flake thickness agree reason- ably well with our experimental measurements. Conversely, measuring the L-h relations of the periodic microstructures in thin graphite flakes could help determine the critical mechan- ical buckling strain εcr and the interface energy γ.展开更多
本文制备了基于机械剥离β-Ga2O3的Ni/Au垂直结构肖特基器件,对该器件进行了温度特性I-V曲线测试.器件表现出了良好的二极管特性,随着温度从300 K升高至473 K,势垒高度从1.08 e V上升至1.35 e V,理想因子从1.32降低至1.19,二者表现出了...本文制备了基于机械剥离β-Ga2O3的Ni/Au垂直结构肖特基器件,对该器件进行了温度特性I-V曲线测试.器件表现出了良好的二极管特性,随着温度从300 K升高至473 K,势垒高度从1.08 e V上升至1.35 e V,理想因子从1.32降低至1.19,二者表现出了较强的温度依赖特性,这表明器件的肖特基势垒存在势垒高度不均匀的问题.串联电阻随温度升高而降低,这主要是热激发载流子浓度升高导致的.本文利用势垒高度的高斯分布对器件的温度特性进行了修正,修正后的势垒高度为1.54 e V,理查孙常数为26.35 A·cm–2·K–2,更接近理论值,这表明利用高斯分布势垒高度的热电子发射模型能够很好地解释Au/Ni/β-Ga2O3肖特基二极管的I-V温度特性问题,这种方法更适合用来测量β-Ga2O3肖特基二极管的电学参数.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51472253 and 51772306)
文摘Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate （DOP） as milling medium without solvent. The obtained mixture could be directly mixed with poly（vinyl chloride） （PVC） for melt-forming, with DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 ×10 6 Ω/ at 1 wt% carbon additive, significantly lower than approx. 7 wt% of raw graphite required for achieving the same level. This value is low enough for practical antistatic criterion of 3 × 10 8 Ω/ . The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite.
文摘基于机械剥离方法,即通过胶带反复剥离高定向热解石墨,制备得到少层石墨烯,并将其作为可饱和吸收体实现了被动谐波锁模掺铒光纤激光器。在抽运功率约135 m W时,获得了中心波长1568.3 nm,脉冲宽度1.82 ps,3 d B带宽1.7 nm,重复频率1.646 MHz的基频锁模激光输出。通过增加抽运功率和调节腔内偏振,可以获得谐波锁模,谐波阶数最高达到基频的47阶(77.36 MHz)。同时,研究了不同阶谐波锁模时,输出功率、脉冲宽度和单脉冲能量的变化。
基金financia support from NSFC(Grant 10832005)the National Basic Research Program of China(Grant 2007CB936803)+1 种基金the National 863 Project(Grant2008AA03Z302)the support from the engineering faculty of Monash University through seed grant 2014
文摘Mechanical exfoliation is a widely used method to isolate high quality graphene layers from bulk graphite. In our recent experiments, some ordered microstructures, consisting of a periodic alternation of kinks and stripes, were observed in thin graphite flakes that were mechanically peeled from highly oriented pyrolytic graphite. In this paper, a theoretical model is presented to attribute the formation of such ordered structures to the alternation of two mechanical processes during the exfoliation： （1） peeling of a graphite flake and （2） mechanical buckling of the flake being sub- jected to bending. In this model, the width of the stripes L is determined by thickness h of the flakes, surface energy Y, and critical buckling strain ecr. Using some appropriate values of y and ecr that are within the ranges determined by other inde- pendent experiments and simulations, the predicted relations between the stripe width and the flake thickness agree reason- ably well with our experimental measurements. Conversely, measuring the L-h relations of the periodic microstructures in thin graphite flakes could help determine the critical mechan- ical buckling strain εcr and the interface energy γ.
文摘本文制备了基于机械剥离β-Ga2O3的Ni/Au垂直结构肖特基器件,对该器件进行了温度特性I-V曲线测试.器件表现出了良好的二极管特性,随着温度从300 K升高至473 K,势垒高度从1.08 e V上升至1.35 e V,理想因子从1.32降低至1.19,二者表现出了较强的温度依赖特性,这表明器件的肖特基势垒存在势垒高度不均匀的问题.串联电阻随温度升高而降低,这主要是热激发载流子浓度升高导致的.本文利用势垒高度的高斯分布对器件的温度特性进行了修正,修正后的势垒高度为1.54 e V,理查孙常数为26.35 A·cm–2·K–2,更接近理论值,这表明利用高斯分布势垒高度的热电子发射模型能够很好地解释Au/Ni/β-Ga2O3肖特基二极管的I-V温度特性问题,这种方法更适合用来测量β-Ga2O3肖特基二极管的电学参数.
