Abstract

A number of the nanocarbon-metal Ni_x-C and Co₅₀-C core–shell structures were obtained from phenol-formaldehyde resin as a carbon precursor using a mechanochemical method and pyrolysis at 1034 °K. The morphology of the obtained core–shell structures was characterized by scanning electron microscopy. The magnetic hysteresis loops of Ni₂₅-C and Co₅₀-C core–shell structures were investigated by using a vibrating sample magnetometer. The work presents the results of investigations of electrical resistivity of nanocarbon-metal Ni_x-C and Co₅₀-C core–shell structures embedded in polyvinyl acetate (PVA). Electrophysical properties of the composite materials (CMs) have been studied in a wide temperature range: 77–293 K. It was found that morphology and composition (the content of the metal phase and its relation to the carbon phase) of Ni_x-C core–shell structures embedded in PVA influences the value of electrical resistivity, its temperature dependence ρ(Т) and δρ/ρ parameter of composites. The materials with the higher content of core–shell structures (Ni₇₅-C and Co₅₀-C) are characterized by the lower electrical resistivity, while the materials with the significant content of separate carbon phase in the form of nanotubes are characterized by the weaker ρ(Т) dependence.

摘要

许多纳米碳金属Ni _x -C 和Co ₅₀ -C 核壳结构是使用机械化学方法和1034 °K 热解从酚醛树脂作为碳前体获得的。通过扫描电子显微镜表征获得的核壳结构的形态。使用振动样品磁强计研究了Ni ₂₅ -C 和 Co ₅₀ -C 核壳结构的磁滞回线。这项工作介绍了纳米碳金属 Ni _x -C 和 Co ₅₀电阻率的研究结果-C 核壳结构嵌入聚醋酸乙烯酯 (PVA)。已经在很宽的温度范围内研究了复合材料 (CMs) 的电物理性能：77-293 K。发现 Ni _x -C 的形态和成分（金属相的含量及其与碳相的关系）嵌入 PVA 中的核壳结构会影响电阻率的值、其温度依赖性ρ ( Т ) 和复合材料的δρ / ρ参数。核壳结构含量较高的材料（Ni ₇₅ -C 和 Co ₅₀-C）的特征在于较低的电阻率，而与单独的碳相的纳米管的形式显著内容的材料的特点是较弱的ρ（Т）依赖性。