Ionic radii (Shannon) for tetrahedral M(IV) ion
These are Shannon ionic radii.
The "efective ionic radii" quoted here assume that the ionic radius of F- is 133 pm and that of O2- is 140 pm. Values depend upon the coordination number and for d-block metals whether or not the metal is in a high or low spin state.
Older "crystal ionic radii" are based upon a radius of six-coordinate F- = 119 pm and are 14-18% larger than effective ioinc radii.
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