Anion ordering and defect structure in Ruddlesden-Popper strontium niobium oxynitrides.
Anion ordering and defect structure in Ruddlesden-Popper strontium niobium oxynitrides.
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Ruddlesden-Popper 锶铌氮氧化物中的阴离子排序和缺陷结构。
DOI：
10.1021/ic049236k
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发表时间：
2004
影响因子：
4.6
通讯作者：
A. Fuertes
中科院分区：
文献类型：
--
作者：
G. Tobias;D. Beltrán;O. Lebedev;G. van Tendeloo;J. Rodríguez;A. Fuertes
Ruddlesden-Popper 家族 (SrO)(SrNbO(2)N)(n) 的 n = 1 成员的晶体结构通过 Rietveld 方法使用中子粉末衍射数据进行了细化。该复合物在 I4/mmm 空间群中结晶，晶胞参数 a = 4.0506(2) 和 c = 12.5936(9) 埃。精炼后的成分为 Sr(2)NbO(3.28)N(0.72)，对应于 Nb 的形式氧化态 +4.72，即 72% Nb(V) 和 28% Nb(IV)。氮原子根据鲍林第二晶体规则排列在铌八面体的赤道位置，因为带电较多的阴离子占据显示较大键强度总和的位置。鲍林第二晶体法则被证明能够预测其他混合阴离子系统中可用晶体位点中阴离子的分布，例如具有 K(2)NiF(4) 结构的卤氧化物和其他氮氧化物。通过高分辨率电子显微镜研究了同一家族的 n = 1 和 n = 2 成员的缺陷结构。观察到沿 c 轴与其他 Ruddlesden-Popper 成员（n = 3、4 和钙钛矿）的反复共生，导致相应电子衍射图案中沿该方向出现条纹。
The crystal structure of the n = 1 member of the Ruddlesden-Popper family (SrO)(SrNbO(2)N)(n) was refined by the Rietveld method using neutron powder diffraction data. This complex crystallizes in the I4/mmm space group with cell parameters a = 4.0506(2) and c = 12.5936(9) angstroms. The refined composition was Sr(2)NbO(3.28)N(0.72), which corresponds to a formal oxidation state for Nb of +4.72, meaning 72% Nb(V) and 28% Nb(IV). The nitrogen atoms order in the equatorial sites of the niobium octahedra according to Pauling's second crystal rule as the more charged anion occupies the site showing the larger bond strength sums. Pauling's second crystal rule is shown to be able to predict the distribution of anions in the available crystallographic sites in other mixed anion systems such as oxyhalides with K(2)NiF(4) structures and other oxynitrides. The defect structure of the n = 1 and n = 2 members of the same family was investigated by high-resolution electron microscopy. Recurrent intergrowth along the c axis with other Ruddlesden-Popper members (n = 3, 4, and perovskite) is observed, resulting in streaking along this direction in the corresponding electron diffraction patterns.