Study On Electrical Conductivity Of Graphene Quantum Dots At Different Tempertures

With the development of graphene technology,the technology of produce the high-quality production of graphene is still not easy,so the physical properties research of graphene fragments is very important,The nm level quantum dots with size effect,the conductivity is one of the important physical parameters,so the research on the conductivity of graphene quantum dots has important application value.The main influencing factors on the conductivity characteristics of graphene quantum dots solution are the concentration of the solution,the temperature of the solution,the magnetic field where the solution is located,the frequency of the solution,and so on.In this paper,the accuracy of 0.001 g high-precision electronic balance were configured graphene quantum dot solution concentration of 0.05g/L,0.1g/L,0.2g/L,0.3g/L,0.4g/L,0.5g/L,0.6g/L,0.8g/L,1.0g/L,1.2g/L,1.4g/L,1.6g/L,1.8g/L,2.0g/L.The conductivity of graphene quantum dots solution and ultra pure water under different physical conditions was measured in the experiment.Preliminary experimental data processing are:(1)Under the same temperature,magnetic field and frequency,the conductivity of graphene quantum dots solution shown an exponential change with the solution concentration,and it is proportional to the square root of the solution concentration,which is generally in accordance with the Debye-Huckel-Onsager square root law of concentration.(2)Under the same conditions of concentration,magnetic field and frequency,the conductivity of graphene quantum dots exhibits an exponential relationship with temperature and a linear relationship with 1/T,which is roughly in accordance with Arrhenius equation.(3)Under the same conditions of concentration,temperature and frequency,the conductivity of the graphene quantum dot solution increases with the magnetic field..(4)under the condition of the same concentration,temperature and magnetic field.The conductivity of graphene quantum dots solution in the low frequency range with the increase of the frequency increases in the high range of products decreases with increasing frequency.At present,the conductivity model and theory of low concentration solution still need to be explored and improved.In this paper,a composite material model with ellipsoidal inclusions was used to establish an effective conductivity model for studying graphene quantum dots solution.By studying effective media theoretical(EMT)model,porous flow theory model and the general effective model(GEM),compared conditions of use models,finally Selected the general effective model(GEM)to fit the concentration dependence of the effective conductivity of the graphene quantum dots.The key index of the system is obtained by fitting the experimental data.The results show that the fitting results are close to the experimental data.The GEM model can be used to predict the effective conductivity of graphene quantum dots solution.Based on the analysis about the tunnel conductivity model and Arrhenius equation,the modified tunnel conductivity model is obtained.The key index of the system is determined by computer simulation.The model can well simulate the temperature dependence of the effective conductivity of graphene quantum dot solution.The correction model can provide a more reliable guidance for the design and optimization of the graphene quantum dot composites.