摘要:
用第一性原理研究放射性同位素铀在针铁矿(α-FeOOH)中的占位情况,分别考虑铀原子替代针铁矿中的铁的替位缺陷和铀的多种八面体和多种四面体间隙缺陷.计算发现了三个最稳定的缺陷构型,它们分别对应于一个铀替位缺陷(S)及其中的一个铀的八面体(O)和四面体(T)间隙缺陷,其形成能分别为?13.49,?3.86,?1.60 eV.也研究了两个相邻的铀原子在针铁矿中的占位情况,发现双铀原子很容易掺入到相邻的SS或OS位,它们的形成能分别为?27.392和?16.214 eV,结合能分别为?0.417和1.131 eV.表明双原子铀在针铁矿中会以SS形式发生偏聚而较难以OS形式偏聚.
关键词:
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铀
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针铁矿
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占位
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第一性原理
Abstract:
@@@@Occupancy sites of uranium atom in goethite are studied by first principles calculations. It is found that the formation energies of substitution (S), octahedral (O), and tetrahedral (T) sites of uranium in goethite are?13.49,?3.86, and?1.60 eV, respectively. The formation energies of dual uranium in S and O sites in goethite are?27.392 and?16.214 eV, respectively, and corresponding binding energies are?0.417 and 1.131 eV, respectively. It is concluded that dual uranium atoms can aggregate together in S site formation in goethite, but not in O site formation.
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