Defect chemistry could be the review of place defects in imperfect crystals. These consist of vacancies, interstitial atoms or ions, trace aspects, electrons, or holes or almost every other deviation from the framework of an ideal crystal. Even Completely pure crystals include place defects at any temperature over complete zero. https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share