Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS, UK.
Inorg Chem. 2009 Feb 16;48(4):1284-92. doi: 10.1021/ic801482a.
Single crystals of four erbium-chromium sulfides have been grown by chemical vapor transport using iodine as the transporting agent. Single-crystal X-ray diffraction reveals that in Er(3)CrS(6) octahedral sites are occupied exclusively by Cr(3+) cations, leading to one-dimensional CrS(4)(5-) chains of edge-sharing octahedra, while in Er(2)CrS(4), Er(3+), and Cr(2+) cations occupy the available octahedral sites in an ordered manner. By contrast, in Er(6)Cr(2)S(11) and Er(4)CrS(7), Er(3+) and Cr(2+) ions are disordered over the octahedral sites. In Er(2)CrS(4), Er(6)Cr(2)S(11), and Er(4)CrS(7), the network of octahedra generates an anionic framework constructed from M(2)S(5) slabs of varying thickness, linked by one-dimensional octahedral chains. This suggests that these three phases belong to a series in which the anionic framework may be described by the general formula M(2n+1)S(4n+3), with charge balancing provided by Er(3+) cations located in sites of high-coordination number within one-dimensional channels defined by the framework. Er(4)CrS(7), Er(6)Cr(2)S(11), and Er(2)CrS(4) may thus be considered as the n = 1, 2, and infinity members of this series. While Er(4)CrS(7) is paramagnetic, successive magnetic transitions associated with ordering of the chromium and erbium sub-lattices are observed on cooling Er(3)CrS(6) (T(C)(Cr) = 30 K; T(C)(Er) = 11 K) and Er(2)CrS(4) (T(N)(Cr) = 42 K, T(N)(Er) = 10 K) whereas Er(6)Cr(2)S(11) exhibits ordering of the chromium sub-lattice only (T(N) = 11.4 K).
已经通过使用碘作为传输剂的化学气相传输方法生长了四种铒-铬硫化物的单晶。单晶 X 射线衍射表明，在 Er(3)CrS(6)中，八面体位置仅被 Cr(3+)阳离子占据，导致一维 CrS(4)(5-)链由共用边的八面体组成，而在 Er(2)CrS(4)中，Er(3+)和 Cr(2+)阳离子以有序的方式占据可用的八面体位置。相比之下，在 Er(6)Cr(2)S(11)和 Er(4)CrS(7)中，Er(3+)和 Cr(2+)离子在八面体位置上是无序的。在 Er(2)CrS(4)、Er(6)Cr(2)S(11)和 Er(4)CrS(7)中，八面体的网络生成由具有不同厚度的 M(2)S(5)片组成的阴离子框架，由一维八面体链连接。这表明这三个相属于一个系列，其中阴离子框架可以用通式M(2n+1)S(4n+3)来描述，通过位于框架定义的一维通道中具有高配位数的位置的 Er(3+)阳离子来提供电荷平衡。因此，Er(4)CrS(7)、Er(6)Cr(2)S(11)和 Er(2)CrS(4)可以被认为是该系列中的 n = 1、2 和无穷大成员。虽然 Er(4)CrS(7)是顺磁性的，但在冷却 Er(3)CrS(6)(T(C)(Cr) = 30 K；T(C)(Er) = 11 K)和 Er(2)CrS(4)(T(N)(Cr) = 42 K，T(N)(Er) = 10 K)时，观察到与铬和铒亚晶格有序化相关的连续磁性转变，而 Er(6)Cr(2)S(11)仅表现出铬亚晶格的有序化(T(N) = 11.4 K)。
