Radial integrals 〈rk〉4f and nephelauxetic effect of Nd3+ in crystals

- The radial integrals 〈rk〉4f, k = 2, 4, 6, of Nd3+ ion are derived semi-empirically.
- The dielectric screening model used relates spectroscopic and dielectric properties.
- The range of the 〈rk〉4f values is close to those from relativistic computations.
- The mean nephelauxetic ratio is related to covalency and bonding parameters.
- This approach is sensitive to the particular crystal containing Nd3+ ions.