The zinc vacancy in ZnSb 2 O 6 has formation energy of 6.58 eV in the neutral charge state, with transition levels from the (0/1-) and (1-/2-) charge states occurring at Fermi levels of 1.20 eV and 1.63 eV, respectively. This is a deep acceptor defect that displays polaronic behaviour, as shown in the charge density plot in Figure . In the neutral charge state, two holes are stabilised, which reduces to one upon the acceptance of an electron from the VBM, and to none upon the acceptance of a second electron. This is analogous to the behaviour seen in the zinc vacancy in ZnO. In environment one, upon V O generation, the two Sb atoms relax inwards by 2.6%, while the Zn relaxes outwards by 6.8%. Upon ionisation to V + O , the two Sb atoms relax outwards by 7.4% from their position in the neutral vacancy, and the Zn relaxes outwards by a further 0.7%. Ionising again to V ++ O causes a further 6.8% outwards relaxation of the Sb atoms and another 0.8% for the Zn atom.