Gao Jian - Academia.edu (original) (raw)

Papers by Gao Jian

Chinese Physics Letters, 2012

We present exact results for the electronic transport properties of graphene sheets connected to ... more We present exact results for the electronic transport properties of graphene sheets connected to two metallic electrodes. Our results, obtained by transfer-matrix methods, are valid for all sheet widths and lengths. In the limit of large width-to-length ratio relevant to recent experiments, we find a Dirac-point conductivity of 2e 2 / √ 3h and a sub-Poissonian Fano factor of 2 − 3 √ 3/π ≃ 0.346 for armchair graphene; for the zigzag geometry these are respectively 0 and 1. Our results reflect essential effects from both the topology of graphene and the electronic structure of the leads, giving a complete microscopic understanding of the unique intrinsic transport in graphene. PACS numbers: 72.80.Vp, 73.22.Pr,73.40.Sx Graphene, a graphite monolayer of carbon atoms forming a honeycomb lattice, has a distinctive electronic structure whose low energy excitations are described by massless Dirac fermions. The successful extraction of micron-scale graphene sheets from a natural graphite crystal, and their deposition onto an oxidized Si wafer [1], was a truly seminal event which ushered in a new era of realistic experimental and theoretical exploration. The subsequent explosion of graphene activity has focused on fundamental questions concerning the transport properties of relativistic particles in graphene and on its potential applications as a high-mobility semiconductor.

Asia-pacific Journal of Chemical Engineering, 2009

The precipitated iron catalyst was prepared by co-precipitation. The surface morphology of the ca... more The precipitated iron catalyst was prepared by co-precipitation. The surface morphology of the catalyst was investigated under different reduction conditions by SEM (S-250, USA). Under H2-reduction, the surface morphology of the catalyst had the obvious changes, which the diameter reduced, adhered together, came into being wads considered as a group. But the surface morphology of the catalyst had almost no change under CO reduction. The crystal structure of the catalyst was studied under different reduction conditions by X-ray diffraction (XRD) (Rigaku D/max, Japanese). It was found that the catalyst was reduced completely with H2, but it was reduced partly with CO. The crystal structure of the catalyst converted into the metallic phase with H2 reduction. However, most of the iron converted into iron oxide (Fe3O4) with CO reduction. And the predominant phase in a sample of a mature catalyst is χ-Fe5C2, which is the active phase in the Fischer-Tropsch synthesis (FTS). The experimental results showed that CO conversion and H2 conversion increase with the change of reaction temperature from 260 to 300 °C, under the conditions of pressure P = 2.6 MPa, space velocity = 0.86 Nl h−1 g-Fe−1, n(H2)/n(CO) = 2/3, and most of the hydrocarbon products are C5−11 which hold half of the hydrocarbon products. The next content is C2−4 which holds the quarter of hydrocarbon products. Then it is C12+, which is equal to 18%. And the last is C1, which is equal to 7%. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

Chinese Physics Letters, 2012

We present exact results for the electronic transport properties of graphene sheets connected to ... more We present exact results for the electronic transport properties of graphene sheets connected to two metallic electrodes. Our results, obtained by transfer-matrix methods, are valid for all sheet widths and lengths. In the limit of large width-to-length ratio relevant to recent experiments, we find a Dirac-point conductivity of 2e 2 / √ 3h and a sub-Poissonian Fano factor of 2 − 3 √ 3/π ≃ 0.346 for armchair graphene; for the zigzag geometry these are respectively 0 and 1. Our results reflect essential effects from both the topology of graphene and the electronic structure of the leads, giving a complete microscopic understanding of the unique intrinsic transport in graphene. PACS numbers: 72.80.Vp, 73.22.Pr,73.40.Sx Graphene, a graphite monolayer of carbon atoms forming a honeycomb lattice, has a distinctive electronic structure whose low energy excitations are described by massless Dirac fermions. The successful extraction of micron-scale graphene sheets from a natural graphite crystal, and their deposition onto an oxidized Si wafer [1], was a truly seminal event which ushered in a new era of realistic experimental and theoretical exploration. The subsequent explosion of graphene activity has focused on fundamental questions concerning the transport properties of relativistic particles in graphene and on its potential applications as a high-mobility semiconductor.

Asia-pacific Journal of Chemical Engineering, 2009

The precipitated iron catalyst was prepared by co-precipitation. The surface morphology of the ca... more The precipitated iron catalyst was prepared by co-precipitation. The surface morphology of the catalyst was investigated under different reduction conditions by SEM (S-250, USA). Under H2-reduction, the surface morphology of the catalyst had the obvious changes, which the diameter reduced, adhered together, came into being wads considered as a group. But the surface morphology of the catalyst had almost no change under CO reduction. The crystal structure of the catalyst was studied under different reduction conditions by X-ray diffraction (XRD) (Rigaku D/max, Japanese). It was found that the catalyst was reduced completely with H2, but it was reduced partly with CO. The crystal structure of the catalyst converted into the metallic phase with H2 reduction. However, most of the iron converted into iron oxide (Fe3O4) with CO reduction. And the predominant phase in a sample of a mature catalyst is χ-Fe5C2, which is the active phase in the Fischer-Tropsch synthesis (FTS). The experimental results showed that CO conversion and H2 conversion increase with the change of reaction temperature from 260 to 300 °C, under the conditions of pressure P = 2.6 MPa, space velocity = 0.86 Nl h−1 g-Fe−1, n(H2)/n(CO) = 2/3, and most of the hydrocarbon products are C5−11 which hold half of the hydrocarbon products. The next content is C2−4 which holds the quarter of hydrocarbon products. Then it is C12+, which is equal to 18%. And the last is C1, which is equal to 7%. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.