Charge distribution, transition metal cation

Since site enrichments in a crystal structure are expressed relative to a host cation, the primary factor affecting the cation distributions is the comparative ionic radius of Mg2+ or Al3+ to a transition metal ion of similar charge. Among... 

There are some cases, however, where with limited data, valid comparisons can be made between transition metals ions and other cations of similar charge and size. It is possible to interpret qualitatively trends in the geochemical distribution of transition metal ions by crystal field theory. 

The selectivity for separating metal ions having the same charge number is exclusively determined by their KM values. The concentration of eluent cations [A+] does not contribute to the selectivity increase, since the differences in the logarithms of the distribution coefficients remain unchanged with different eluent concentrations. Adequate separations are only obtained if the selectivity coefficients of two transition metal ions... 

Much work has been carried out in order to optimize LiNi02 s composition and structure in order to make the system easily reversible in batteries, as well as in order to achieve better thermal stability in the deintercalated state (i.e. when the battery is charged) to make the accumulator safer. Partial substitutions for nickel have been envisaged (LiNii-yMy02 compositions). Cationic substitution effectively allows the crystal field to be modified around the transition metal and thus enables the stabilized oxidation states of ions to be modified, as well as the cationic distributions between the different sites, etc. [DEL 99b]. These substituted materials are most often synthesized by coprecipitation since, compared to a solid-state reaction (mixture of oxides of different elements), this method enables a better local distribution of cations to be achieved. 

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