Tunable electrical properties of C_(60)·m-xylene and the formation of semiconducting ordered amorphous carbon clusters under pressure  

作　　者：Zhongyan Wu Guoying Gao Jinbo Zhang Alexander Soldatov Jaeyong KimLin Wang Yongjun Tian 

机构地区：[1]Department of Physics,Institute for High Pressure Research,Hanyang University,Seoul 04763,Republic of Korea [2]Center for High Pressure Science(CHiPS),State Key Laboratory of Metastable Materials Science and Technology,Yanshan University,Qinhuangdao 066004,China [3]College of Physical Science and Technology,Yangzhou University,Yangzhou 225002,China

出　　处：《Nano Research》2022年第4期3788-3793,共6页纳米研究（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China(Nos.52090020 and 11874076);National Research Foundation of Korea(Nos.2016K1A4A3914691 and 2018R1D1A1B07049811).

摘　　要：Ordered amorphous carbon clusters(OACC)transformed from m-xylene solvated C_(60)(C_(60)·m-xylene)are known as the first crystalline material constructed from amorphous building blocks and have attracted a lot of attention.The formation mechanism and physical properties of this material are of great importance for the design of more materials with such structural characteristics.In this article,the transport and structural properties of C_(60)·m-xylene are systematically investigated under pressure using impedance spectroscopy,four-probe resistance measurements,and Raman spectroscopy.It is found that C_(60)·mxylene is an insulator at ambient pressure.The resistance decreases sharply starting at the pressure around 8 GPa due to the pressure-induced dimerization of C_(60)verified by the Raman study.The presence of solvent hinders further polymerization of C_(60)under higher pressures.The temperature-dependence of resistance exhibits a semiconducting characteristic at>8-26.9 GPa,and is well described by Mott's three-dimensional variable-range hopping model(3D-VRH),indicating an insulating-tosemiconducting transition accompanied with pressure-induced dimerization.The resistance and hopping energy are both found to decrease monotonically with pressure and reach the minimum near 24 GPa.Above the pressure,resistance and hopping energy values start to rise,suggesting a transition to another semiconducting state,which is attributed to the pressure-induced formation of OACC.The conductivity shows a large hysteresis during decompression from higher than 24 GPa,confirming a different transport behavior of the sample with retained fullerenes versus OACC.The findings of our study suggest that the transport property of fullerene is tunable by introducing solvates and further enhance our understanding of the OACC.

关 键 词：fullerene solvate high pressure electrical transport DIMERIZATION insulating-semiconducting transition 

分 类 号：O62[理学—有机化学]