Tetravalent doping of CeO$_2$: The impact of valence electron character on group IV dopant influence

摘要

Fluorite CeO$_2$ doped with group IV elements is studied within the DFT andDFT+U framework. Concentration dependent formation energies are calculated forCe$_{1-x}$Z$_x$O$_2$ (Z= C, Si, Ge, Sn, Pb, Ti, Zr, Hf) with $0\leq x \leq0.25$ and a roughly decreasing trend with ionic radius is observed. Theinfluence of the valence and near valence electronic configuration isdiscussed, indicating the importance of filled $d$ and $f$ shells near theFermi level for all properties investigated. A clearly different behavior ofgroup IVa and IVb dopants is observed: the former are more suitable for surfacemodifications, the latter are more suitable for bulk modifications.\\ \indentFor the entire set of group IV dopants, there exists an inverse relationbetween the change, due to doping, of the bulk modulus and the thermalexpansion coefficients. Hirshfeld-I atomic charges show that charge transfereffects due to doping are limited to the nearest neighbor oxygen atoms.