"Crystal radius" vs "Ionic radius"

What is the difference between *crystal radius* and *ionic radius*? For $\ce{NaCl}$ for example the ions combine to a crystal, and I would have guessed they are equal. But I then found an example of data, where they are not.


I am aware that [ionic radius](http://en.wikipedia.org/wiki/Ionic_radius) is the radius of an atom's ion. Quite simple. So what is *crystal radius*?




To quote Erik Rakovský · 30.73 · 54.96 · Comenius University in Bratislava (from [this](https://www.researchgate.net/post/Difference_between_Crystal_Ionic_Radius_and_Effective_Ionic_Radius#view=56b050e07dfbf9d1cf8b4583) discussion on researchgate)


Shannon published simultaneously two sets of ionic radii. So called "effective ionic radii" were made consistent with Pauling's r($\mathrm{O\_2^-}$)=140 pm. "Crystal radii" are using Shannon's value r($\mathrm{O\_2^-}$)=126 pm.


<https://dx.doi.org/10.1107%2FS0567739476001551>


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