Laboratory of Crystallography, University of Bayreuth, D-95440 Bayreuth, Germany.
J Phys Condens Matter. 2013 Feb 20;25(7):076003. doi: 10.1088/0953-8984/25/7/076003. Epub 2013 Jan 17.
Crystal structure analyses of the layered compounds La(n)(Ti(1-x)Fe(x))(n)O(3n+2), with nominal compositions x = 0.2 for n = 5 and x = 0.33 for n = 6, show that the iron is concentrated at the centers of the slabs. The spatial arrangements of the iron ions can be approximated by two-dimensional square lattices with strong magnetic interactions between neighboring sites, albeit with fractional occupancies of the sites of an average of 0.67 magnetic ions in n = 6 and 0.42 magnetic ions in n = 5 compounds. A previously described (Lichtenberg et al 2008 Prog. Solid State Chem. 36 253) crossover of magnetic behavior of n = 6 at room temperature is explained by the formation of two-dimensional, ferromagnetically organized magnetic clusters with an average size of 52 Fe(3+) ions. The absence of long-range magnetic order follows from the fractional occupancy of the sites by the magnetic ions. The lower concentration of magnetic ions in n = 5 explains why crossover behavior is not found and clusters do not form in that compound.
层状化合物 La(n)(Ti(1-x)Fe(x))(n)O(3n+2)（其中 n = 5 时 x = 0.2，n = 6 时 x = 0.33）的晶体结构分析表明，铁集中在层板的中心。铁离子的空间排列可以用二维正方形晶格来近似，尽管相邻位置之间存在强烈的磁相互作用，但平均每个位置的铁离子占据率为 0.67（在 n = 6 的化合物中）和 0.42（在 n = 5 的化合物中）。之前描述过（Lichtenberg 等人，2008 年，Prog. Solid State Chem. 36 253）室温下 n = 6 的磁行为交叉现象可以用二维、铁磁有序的磁性簇的形成来解释，其平均大小为 52 个 Fe(3+)离子。由于磁性离子的占据位置是分数的，所以没有长程磁有序。n = 5 中磁性离子浓度较低的原因是为什么在该化合物中没有发现交叉行为并且没有形成簇。
