Defect chemistry may be the review of level defects in imperfect crystals. These involve vacancies, interstitial atoms or ions, trace features, electrons, or holes or any other deviation from the composition of a perfect crystal. Even Completely pure crystals consist of position defects at any temperature above complete zero. Right https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share