In metal excess defect of solids (which is non-stoichometric defect) where does the NaCl formed go??plze xplain its concept

An ideally perfect crystal is defined as the one which has the same unit cell and contains the same lattice points throughout the crystal.However imperfections or defects generally arises.These imperfections are defined as any deviation of the ideally perfect crystal from the periodic arrangement of its constituents.If the deviation occurs because of missing atoms, displaced atoms or extra atoms, the imperfection is named as apoint defect.Point-defects are of three types.Non-stoichiometric is one of them.
If the ratio of number of cation to anion becomes different from that indicated by the ideal chemical formula, the defects are called non – stoichiometric defects which arises either due to excess of metal atoms or non metal atom or presence of impurities / foreign particle.It is found that if a crystal of NaCl is heated in sodium vapour, it acquires a yellow colour.This yellow colour is due to the formation of a non-stoichiometric compound of sodium chloride in which there is a slight excess of sodium ions.Some sodium metal gets doped into sodium chloride crystal which, due to the crystal energy, gets ionised into Na⁺and e^–. This electron occupies a site that would otherwise be filled by a chloride ion.The extra electron is shared between all the six Na+ions which implies that this electron is not localised at the vacant Cl–site. On the other hand, this electron is similar to the delocalised p electrons present in molecules containing conjugate double bonds.
The non-stoichiometric sodium chloride may be represented by the formula Na(1+d)Cl where d is the excess sodium metal doped in the crystal because of its exposure to sodium vapour.