Atomistic modelling of iodine-oxygen interactions in strained sub-oxides of zirconium

•Higher oxygen content increases the formation energies of iodine defects.•3% hydrostatic strain decreases the defect formation energy more in structures with higher oxygen content.•The competition between iodine and oxygen is strain dependent.•Iodine can be favoured in the bulk Zr over oxygen terminated surfaces under tension (>1%).