The ionic radius of nickel
COMPILATIONS of ionic radii in common use are due to Ahrens 0952) and Pauling
096o). According to both the Ni 2+ ion is larger than the Mg 0-+ (Ahrens, Ni 2~- o'69 A,
Mg "+ o-66 A; Pauling, Ni -0+ o'72/~, Mg 2" o'65 A), but a comparison of the unit cell
volumes of many isomorphous nickel and magnesium compounds reveals that the
nickel compound normally has a smaller cell volume. This provides sufficient evidence
for a revision of the estimated relative ionic radii of nickel and magnesium.
The unit cell volumes of nineteen pairs of nickel and magnesium compounds that were believed to be isostructural were calculated from the data of the ASTM card index 0967). The ratio of the cell volume of the nickel compound to that of the magnesium compound, V x~:V~g, was then calculated (table I). In only two of the structures was the ratio greater than i-oo and it is tentatively suggested that these two cases result from faulty data.
To download the article click on the link below:
http://www.minersoc.org/pages/Archive-MM/Volume_37/37-286-299.pdf
The unit cell volumes of nineteen pairs of nickel and magnesium compounds that were believed to be isostructural were calculated from the data of the ASTM card index 0967). The ratio of the cell volume of the nickel compound to that of the magnesium compound, V x~:V~g, was then calculated (table I). In only two of the structures was the ratio greater than i-oo and it is tentatively suggested that these two cases result from faulty data.
To download the article click on the link below:
http://www.minersoc.org/pages/Archive-MM/Volume_37/37-286-299.pdf
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