FeO is found with a composition of Fe0.95O. It ranges from Fe0.93O to Fe0.95O. Which type of defect is it showing here?
Metal-deficiency
For ideal crystal the formula is FeO means for every one atom of oxygen there is one atom of Fe. If it is metal deficiency defect there is less amount of metal for the anion.That's why the general formula is Fe1-xO.