Eur. Phys. J. B 22, 179-186 (2001)
https://doi.org/10.1007/PL00011142

Vanadium valency and hybridization in V-doped hafnia investigated by electron energy loss spectroscopy

¹ Centre d'Élaboration de Matériaux et d'Études Structurales CEMES, 29, rue Jeanne Marvig, BP 4347, 31055 Toulouse Cedex 4, France
² Laboratoire de Matériaux Microelectronique de Provence (L2MP) (CNRS UMR 6137) , Université de Toulon et du Var, bâtiment R, BP 132, 83957 La Garde Cedex, France

Corresponding author: ^a agloter@univ-mlv.fr

Received: 17 November 2000
Revised: 17 April 2001
Published online: 15 July 2001

Abstract

The valency of vanadium, and thus indirectly the oxygen stoichiometry, of V-doped hafnia synthesized under different atmospheres have been investigated on a nanometer scale by means of electron energy loss spectroscopy (EELS). The EELS V L_2,3 spectra are compared with the results of crystal field multiplet calculations and experiments on reference vanadium oxides. The EELS spectra indicate that V-doped hafnia prepared under reducing (H₂) and neutral (Ar) atmosphere are unambiguously substituted with trivalent vanadium atoms leading to the creation of oxygen vacancies in the structure. On the contrary, stoichiometric (Hf, V)O₂ compound (i.e. V⁴⁺) is more likely to be stabilized under oxidative (air) atmospheres. We also show that the amount of hybridization alters for the different compounds studied but may in part be analyzed by high spatially resolved EELS. The crystal field multiplet calculations particularly indicate that a simple reduction of the Slater integrals gives a good account of the spectral modification induced by hybridization for the case of tetravalent vanadium atoms.