The thermodynamic state and kinetic process of low-temperature deoxygenation reaction of graphene oxide(GO) have been investigated for better understanding on the reduction mechanism by using Differential Scanning Calorimetry(DSC), Thermogravimetry-Mass Spectrometry(TG-MS), and X-ray Photoelectron Spectroscopy(XPS). It is found that the thermal reduction reaction of GO is exothermic with degassing of CO_2, CO and H_2O. Graphene is thermodynamically more stable than GO. The deoxygenation reaction of GO is kinetically controlled and the activation energy for GO is calculated to be 167 k J/mol(1.73 e V/atom).
Kuibo YinHaitao LiYidong XiaHengchang BiJun SunZhiguo LiuLitao Sun
The local thermal conductivity of polycrystalline aluminum nitride （A1N） ceramics is measured and imaged by using a scanning thermal microscope （SThM） and complementary scanning electron microscope （SEM） based techniques at room temperature. The quantitative thermal conductivity for the A1N sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3w method. A thermal conductivity of 308 W/m-K within grains corresponding to that of high-purity single crystal A1N is obtained. The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations, as demonstrated in the electron backscattered diffraction. A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites, as indicated by energy dispersive X-ray spectroscopy.
Zhang Yue-FeiWang LiR.HeiderhoffA.K.GeinzerWei BinJi YuanHan Xiao-DongL.J.BalkZhang Ze
