© The Authors.In this contribution, the shape coexistence phenomenon near the Z=40 proton sub-shell closure is analyzed for both even-even and odd nuclei around neutron number N=60. The onset of deformation is compared in even and odd nuclei using the intrinsic state formalism of the Interacting Boson Fermion Model with configuration mixing, which is presented for the first time in this contribution. The Nb isotopes are studied in detail showing that the onset of deformation can be explained in terms of the crossing of two configurations leading to a Type II Quantum Phase Transition.