High-temperature synthesis, crystal structure, optical properties, and magnetism of the carbidonitridosilicates Ho2[Si4N6C] and Tb2[Si4N6C]
High-temperature synthesis, crystal structure, optical properties, and magnetism of the carbidonitridosilicates Ho2[Si4N6C] and Tb2[Si4N6C]
复制标题
DOI：
10.1039/b106533p
复制
发表时间：
2001-01-01
影响因子：
--
通讯作者：
Schnick, W
中科院分区：
文献类型：
--
作者：
Höppe, HA;Kotzyba, G;Schnick, W
在1700 ℃的射频炉中，通过相应的镧系金属与碳和Si（NH）（2）的反应，获得了新型的碳氮硅酸盐Ho-2[Si 4 N6 C]和Tb-2[（SiNC）-N-4-C-6]。根据Ho-2[Si 4 N6 C]的单晶结构分析（P2（1）/c，Z=4，a=593.14（1），B=989.74（1），c=1188.59（2）pm，β =119.58（4）度，R1=0.0355，wR 2 =0.0879，2187 F-2值，119个参数），该化合物含有角共享星星状[C（SiN 3）（4）]单元的缩合网络。钬离子位于沿着[100]的通道中。Ho-2[Si 4 N6 C]的紫外-可见吸收光谱显示出典型的Ho ~（3+）吸收带。光谱结果表明，4f态几乎不受配位球的影响，因此在UV-VIS光谱中不可能区分Ho 3+的两个晶体学位置。Tb-2[Si_4 N_6C]和Ho-2[Si_4 N_6C]的磁化率测量表明在150 K以上具有Curie-Weiss行为，实验磁矩分别为9.57（6）mu（B）/Tb和10.27（4）mu（B）/Ho。铽和钬化合物的韦斯常数分别为-15（1）K和-11（1）K。低至2K时，无法检测到磁有序。在2 K的磁化曲线显示的增加的磁化强度与增加的磁通密度，表明部分平行自旋对齐。在5 T下，磁化强度分别达到4.15（5）μ（B）/Tb和4.75（5）μ（B）/Ho。
The novel carbidonitridosilicates Ho-2[Si4N6C] and Tb-2[(SiNC)-N-4-C-6] were obtained by the reaction of the respective lanthanoid metal with carbon and Si(NH)(2) in a radiofrequency furnace at the temperature of 1700 degreesC. According to the single-crystal structure analysis of Ho-2[Si4N6C] (P2(1)/c, Z=4, a=593.14(1), b=989.74(1), c=1188.59(2) pm, beta =119.58(4)degrees, R1=0.0355, wR2=0.0879, 2187 F-2 values, 119 parameters) the compound contains a condensed network of corner-sharing star like [C(SiN3)(4)] units. The holmium ions are situated in channels along [100]. The UV-VIS absorption spectrum of Ho-2[Si4N6C] shows the typical Ho3+ absorption bands. The spectroscopic results show that the 4f states remain almost unaffected by the coordination sphere and thus it is impossible to distinguish between the two crystallographic sites of Ho3+ in the UV-VIS spectrum. Magnetic susceptibility measurements of Tb-2[Si4N6C] and Ho-2[Si4N6C] show Curie-Weiss behaviour above 150 K with experimental magnetic moments of 9.57(6) mu (B)/Tb and 10.27 (4) mu (B)/Ho. The Weiss constants are -15(1) K and -11(1) K for the terbium and holmium compounds, respectively. Down to 2 K no magnetic ordering could be detected. The magnetization curves at 2 K show an increase of the magnetization with increasing flux density, indicating partial parallel spin alignments. At 5 T the magnetizations reach values of 4.15(5) mu (B)/Tb and 4.75(5) mu (B)/Ho, respectively.