Rationalization of the Pr3+- to-transition metal charge transfer model: Application to the luminescence of Pr3+ in titano-niobates

The Pr3+-to-d(0) transition metal (Mn+) charge transfer model introduced in 2007 under the acronym 'IVCT' is revisited and rationalized in the frame of the chemical shift model introduced in 2012 by P. Dorenbos. The rationalization involves slight refinements of the Coulomb repulsion energy U(A) for titanates, vanadates, nio- bates, tantalates, molybdates and tungstates and allows prediction of Pr3+ -> Mn+ charge transfer energies with an accuracy of +/- 0.1 to +/- 0.15 eV, depending on the considered family.