反铁磁氧化物NiO的表面化学性质研究

来源 :第十二届全国量子化学会议 | 被引量 : 0次 | 上传用户:cmz
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  过渡金属氧化物广泛运用在多相催化体系中,作为分散并稳定贵金属催化剂的载体或者直接作为活性相催化化学反应.催化研究的发展要求对这类材料的表面化学性质有全面深入的理解3d过渡金属Mn,Fe,Co,Ni的氧化物是相对特殊的一类氧化物材料,具有强关联的电子结构以及典型的铁磁性或反铁磁性,他们的磁性质在电子学及磁学领域得到广泛的关注,而这种磁性电子结构对表面化学性质的影响还鲜有研究.以NiO为代表的岩盐结构氧化物(MnO,FeO,CoO,NiO)具有典型的反铁磁性.中子衍射实验在1950年代就确定他们在Neel温度以下的体相磁性结构为反铁磁Ⅱ型(AFMⅡ)1,最近通过磁交换作用力显微镜(MExFM)直接观测到了NiO(001)表面Ni原子的磁相对取向2,3.磁性材料合成方面的进展表明在尺寸效应或者缺陷的影响下,磁性氧化物表面局部磁性结构会发生变化而不同于体相4,5.以此为背景,本工作以NiO为模型体系,构建由Ni离子磁取向不同而去简并化的表面模型,以小分子为探针,考察表面磁性结构对表面吸附等化学性质的影响.结果表明,不同类型分子表面吸附对表面局部磁性变化有不同响应,我们给出了表面局部磁性对这些小分子吸附性能的影响范围.
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