Towards the growth of stoichiometric chromia on pure chromium by the control of temperature and oxygen partial pressure

•The identification of the nature of point defects in chromia has been demonstrated thanks to TEM and photoelectrochemical characterization.•The duplex morphology (equiaxis & columnar) does not depend on the nature of the point defect but on the growth direction (either inward or outward).•A stoichiometric chromia has been grown by adjusting the oxygen partial pressure.