Lanthanide ions atomic orbitals

Electron transitions in transition-metal ions usually involve electron movement between the d orbitals (d-d transitions) and in lanthanides between the / orbitals (/-/ transitions). The band structure of the solid plays only a small part in the energy of these transitions, and, when these atoms are introduced into crystals, they can be represented as a set of levels within the wide band gap of the oxide (Fig. 9.15). 

Equation (S6.1) is applicable to the salts of lanthanide ions. These have a partly filled 4f shell, and the 4f orbitals are well shielded from any interaction with the surrounding atoms by filled 5.9, 5p, and 6.9 orbitals, so that, with the notable exceptions, Eu3+ and Sm3+, they behave like isolated ions. For the transition metals, especially those of the 3d series, interaction with the surroundings is considerable. Because of this, the 3d transition-metal ions often have magnetic dipole moments corresponding only to the electron spin contribution. The orbital moment is said to be quenched. In such materials Eq. (S6.1) can then be replaced by a spin-only formula ... 

Lanthanide ions have a high affinity for hard donor atoms, and ligands containing oxygen or oxygen-nitrogen atoms may be employed in the preparation of lanthanide polymeric complexes. Lanthanide ions present only little preference in bond direction, due to the inner positioning of their 4f valence orbitals. 

In the rows of the periodic system, the valence electrons always shield themselves in an imperfect way from the nuclear charge. This results in an increase in effective nuclear charge, when moving from left to right in a row in the periodic system. The lanthanides show contraction of the atomic and ionic radii, due to the imperfect shielding of the valence f-orbitals. Because there are 14 elements in this series, the effect is more pronounced than other rows of the periodic table. Because the 4f-orbitals are limited in size, the size of the lanthanide ions is defined by their 5 s and 5p orbitals (Platt 2012). 

The five d orbitals of a transition metal atom B are degenerate however, with more than one electron in the d manifold, the spin degeneracy is removed by the ferromagnetic direct-exchange interaction between electron spins in atomic orthogonal orbitals. Transition metal B cations usually introduce filled and/or empty d states within the gap between the anion p bands and lanthanide 5d bands, which lowers the probability that the lanthanide ion can have two valence states in a transition metal perovsldte. 

Electronic Structure of Trivalent Lanthanide Ions 1.1 Atomic Orbitals... 

It is of interest to compare the radial wave functions between 4f and 5f elements. O Figure 18.19 shows relativistic calculations of and Am valence wave functions of the radial part. This figure indicates that the 4f subshell of Eu is core like because of the lower density around the ionic radius of the ion. In the corresponding 5f ion, Am, 5f subshell penetrates the 6s and 6p orbitals. The wider distribution of the 5f orbital allows much participation in bonding for the actinides than for the lanthanides. The 4f orbitals of lanthanide atoms are mainly localized in the core and do not contribute to the chemical bonding. 

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