Cobalt(III) Effect on 27Al NMR Chemical Shifts in LiAlxCo1-xO2
Cobalt(III) Effect on 27Al NMR Chemical Shifts in LiAlxCo1-xO2
复制标题
钴 (III) 对 LiAlxCo1-xO2 中 27Al NMR 化学位移的影响
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
J. Tirado
中科院分区：
文献类型：
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作者：
E. Gaudin;F. Taulelle;R. Stoyanova;E. Zhecheva;R. Alcántara;P. Lavela;J. Tirado
基于柠檬酸盐前体的制备路线用于获得LiAlxCo 1-xO 2固溶体在整个组成范围内。从XRD，IR和NMR的化合物已被证明是由Al的层的八面体网站的Co的替代。在11.7T强磁场下，采用高速旋转的方法对这些产物进行了详细的~（27）Al、~（59）Co和~（71）Li MAS NMR研究。铝被六种第二近邻金属包围。Co/Al取代导致+7ppm的几乎规则的化学位移增量，因此对于被六个钴原子包围的铝给出62.5ppm的最大化学位移。这个值在四面体环境的“经典”化学位移范围内，但却是八面体环境的特征。尽管27 Al NMR化学位移的这一不寻常的方面，所有其他的NMR，XRD和IR观察收敛到一个一致的描述相作为一个连续的固态溶液的八面体网站随机占领的Co或Al…
A preparative route based on citrate precursors is used to obtain LiAlxCo1-xO2 solid solutions over the whole composition range. From XRD, IR, and NMR the compounds have been shown to be a substitution of Co by Al in the octahedral sites of the layer. A detailed 27Al, 59Co, and 7Li MAS NMR study is carried out on these products by using a high spinning speed in a high magnetic field (11.7 T). Aluminum is surrounded by six second-neighbor metals. Co/Al substitution leads to an almost regular chemical shift increment of +7 ppm, thus giving a maximum chemical shift of 62.5 ppm for the aluminum surrounded by six cobalt atoms. This value is in the “classical” chemical shift range of tetrahedral environments but is, however, characteristic of an octahedral environment. Despite this unusual aspect of the 27Al NMR chemical shift, all the other NMR, XRD, and IR observations converge to a consistent description of the phase as being a continuous solid state solution of octahedral sites randomly occupied by Co or Al...