在高密度石墨薄膜中电热导电的异质性和热导电性
Vladimir A Shulyak1, Nikolai S Morozov1, Alexandra V Gracheva1
1Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia.
Nanomaterials (Basel, Switzerland)
|July 13, 2024
概括
增加柔性石墨的密度可以显著提高电和热导率. 这种改进与热膨胀石墨 (TEG) 颗粒中介质结构和纳米结构的变化有关,导致异构性质.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 纳米技术 纳米技术
背景情况:
- 柔性石墨薄膜是关键材料,需要高电热导电性的应用.
- 了解材料密度,微观结构和运输特性之间的关系对于优化性能至关重要.
- 酸盐方法是生产石墨薄膜的常用技术.
研究的目的:
- 为了研究增加密度对柔性石墨薄膜的特定电热导电性的影响.
- 阐明介质结构和纳米结构因素在导电性和异质性决定中的作用.
- 开发和验证一个介质结构模型,解释观察到的属性增强.
主要方法:
- 使用酸盐方法制备不同厚度 (282-746微米) 的柔性石墨薄膜,初始密度为0.70g/cm3.
- 通过滚动,可控制地增加薄膜密度,达到1.75g/cm3.
- 测量特定的电和热导电性.
- 电子显微镜和X射线分析以表征中介结构和纳米结构特征,包括粒子形状,方向和晶体结构.
- 应用一个中度结构模型和凯恩斯参数用于异质性分析.
主要成果:
- 电导率从69增加到192kS/m,热导率从109增加到326W/m·K,因为密度从0.70增加到1.75g/cm3.
- 电子显微镜显示,更密集的薄膜呈现出延长,缩小的热膨胀石墨 (TEG) 颗粒,接触面积更大.
- 由于粒子旋转,增加的密度导致较厚的薄膜 (> 200μm) 中更大的连贯散射区域,而较薄的薄膜 (< 200μm) 显示出塑性变形.
- 滚动减少了纳米晶体的误导角度,特别是在滚动方向上,从而产生异型电力和机械性能 (异型电力系数高达1.16).
结论:
- 柔性石墨薄膜的密度是一个关键参数,影响其电导和热导率.
- 观察到的增强和异构性是由中结构 (TEG粒子形态和接触) 和纳米结构 (晶体方向和大小) 因素决定的.
- 拟议的半导体结构模型成功地解释了导电性增加和异形性,通过实验和X射线衍射数据验证.
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