Room-temperature magnetic anisotropy of lanthanide complexes:: A model study for various coordination polyhedra
Room-temperature magnetic anisotropy of lanthanide complexes:: A model study for various coordination polyhedra
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DOI：
10.1063/1.1450543
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发表时间：
2002-03-15
影响因子：
4.4
通讯作者：
Binnemans, K
中科院分区：
文献类型：
--
作者：
Mironov, VS;Galyametdinov, YG;Binnemans, K
采用基于数值计算的模型方法，定量分析了镧系配合物的室温磁各向异性与配位多面体类型和镧系离子性质的关系。本研究的目的是建立稀土配合物在室温下磁各向异性的符号和大小变化的一般规律，并估计其最大值。除某些特殊情况外，同构镧系配合物磁性各向异性符号的变化遵循一般符号规律，即Ce（III）、Pr（III）、Nd（III）、Sm（III）、Tb（III）、Dy（III）和Ho（III）配合物具有一个德尔塔奇符号，而Eu（III）、Er（III）、Tm（III）和Yb（III）配合物具有相反的符号。根据配位多面体的不同，Tb（III）、Dy（III）和Tm（III）配合物的磁各向异性最大，其绝对值可达50 000 × 10(-6) cm(3) mol（-1）以上。本研究结果有助于分析含镧液晶和掺杂镧双层胶束在外加磁场下的取向行为。利用Bleaney理论定量分析镧系化合物的磁各向异性具有局限性，因为镧系离子的地面多重体的晶体场分裂能与室温下的热能之间的比例很大。(C) 2002年美国物理研究所。
The dependence of the room-temperature magnetic anisotropy Deltachi of lanthanide complexes on the type of the coordination polyhedron and on the nature of the lanthanide ion is quantitatively analyzed in terms of a model approach based on numerical calculations. The aim of this study is to establish general regularities in the variation of the sign and magnitude of the magnetic anisotropy of lanthanide complexes at room-temperature and to estimate its maximal value. Except for some special cases, the variation of the sign of the magnetic anisotropy over the series of isostructural lanthanide complexes is found to obey a general sign rule, according to which Ce(III), Pr(III), Nd(III), Sm(III), Tb(III), Dy(III), and Ho(III) complexes have one sign of Deltachi and Eu(III), Er(III), Tm(III), and Yb(III) complexes have the opposite sign. Depending on the specific coordination polyhedron, a maximal magnetic anisotropy is observed for Tb(III), Dy(III), or Tm(III) complexes, and its absolute value can reach 50 000x10(-6) cm(3) mol(-1) or more. Results of the present study can be helpful for the analysis of the orientational behavior of lanthanide-containing liquid crystals and lanthanide-doped bilayered micelles in an external magnetic field. The use of the Bleaney theory in the quantitative analysis of the magnetic anisotropy of lanthanide compounds is shown to have limitations because of a large ratio between the crystal-field splitting energy of the ground multiplet of the lanthanide ion and the thermal energy at room-temperature. (C) 2002 American Institute of Physics.