纳米碳中的微观缺陷结构特征

测定了定向石墨和纳米碳的正电子寿命谱,结果表明,热解法制备的纳米碳存在开空间小于单空位的自由体积以及开宽间相当于约１０个空位聚集体全的微孔洞,比较了热解法制备的纳米碳,ＵＦＰ冷压法制备的纳米Ｆｅ和纳米ＴｉＯ２以有非晶晶化法制备的纳米ＮｉＰ的缺陷结构特征,结果为纳米ＮｉＰ中缺陷的电子密度最高,纳米Ｆｅ和纲米ＴｉＯ２次之,纳米碳的最低,纳米碳中的缺陷浓度最高,纳米Ｆｅ和纳米ＴｉＯ２的次之,纳米ＮｉＰ的

Microdefects in nanocrystalline carbon

The positron lifetime spectra of directional graphite and nanocrystalline carbon have been measured. Two kinds of microdefect were found in the nanocrystalline carbon prepared by the heat- dissolve method:free volumes (with a size smaller than that of a monovacancy) and microvoids (with a size of about ten monovacancies). The lifetimes measured , and the corresponding interfacial defects in the samples are discussed in comparison with the nanocrystalline iron and TiO2 materials, prepared by " compacting ultrafine powders" method and the nanocrystalline NiP material prepared by the crystallization method.