What type of defect can arise when a solid is heated? Which physical property is affected by it, in what way?

Explanation

When a solid is heated, vacancy defect arises in the solid. The presence of vacancy defect in the crystal structure of a solid decreases the density of the solid because a solid with this defect contains lesser number of constituent particles than it would have, if there were no defect.
Heating a solid also generates metal excess defect (a non-stoichiometric defect) in the crystal of the solid. The crystal structure of a solid with excess defect contains free electrons which absorb energy from white light and undergo electronic transition. This imparts colour to a solid which is otherwise colourless. The presence of free electrons also increases slightly the electrical conductivity of the solid.