[INVITED] Improved parameters for the lanthanide 4f&lt;sup&gt;q&lt;/sup&gt; and 4f&lt;sup&gt;q−1&lt;/sup&gt;5d curves in HRBE and VRBE schemes that takes the nephelauxetic effect into account

Dorenbos, P.

doi:10.1016/j.jlumin.2020.117164

[INVITED] Improved parameters for the lanthanide 4f^q and 4f^q−15d curves in HRBE and VRBE schemes that takes the nephelauxetic effect into account

Title

[INVITED] Improved parameters for the lanthanide 4f^q and 4f^q−15d curves in HRBE and VRBE schemes that takes the nephelauxetic effect into account

Author

Dorenbos, P. (TU Delft RST/Luminescence Materials)

Date

2020

Abstract

In first approximation the binding of an electron in lanthanide 4f^q ground states changes with q in a characteristic zigzag shape that is independent on type of compound. Those shapes have been parameterized in past publications and are used to construct host referred binding energy (HRBE) or vacuum referred binding energy (VRBE) schemes showing the lanthanide 4f^q level locations with respect to the host valence bands or to the vacuum level. There is experimental evidence for a slight compound dependence, and a model explaining that has appeared recently (Dorenbos, 2019). This all implies that the parameters for constructing HRBE and VRBE schemes need to be revised and a compound dependence needs to be introduced as a second order approximation. In this work the improved parameters are derived from the 3^rd and 4^th ionization potentials of the lanthanide atoms. In compounds, as explained by the chemical shift model, the free ion binding energy curves undergo an upward shift due to Coulomb repulsion from anion ligands and they undergo a tilt due to the lanthanide contraction. In this work we will use the nephelauxetic parameter β to add a compound dependence. Its main effect is an increased binding in the 4f^q ground states for the lanthanides from the right hand branch (q > 7) of the zigzag curves. The same applies for the 4f^q−15d excited states with (q−1)>7. Collected spectroscopic data on divalent and trivalent lanthanides from more than 1000 different compounds have been analyzed to arrive at the proposed revised parameters for the 4f^q and 4f^q−15d binding energy curves.

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DOI

https://doi.org/10.1016/j.jlumin.2020.117164

ISSN

0022-2313

Source

Journal of Luminescence, 222

Part of collection

Institutional Repository

Document type

journal article