Optical property of nature source: UV–visible emissions from calcined oyster shells

Abstract Calcination of oyster shells produces vacancies of Ca and O acting as color centers. Light emissions take place at 20 K and 300 K with intensity much greater than value observed in ZnO nanocrystals. Optical transitions proceed through three-body mechanisms where non-radiative processes involve transverse acoustical and optical phonons. Oxides purchased from suppliers are nearly optical silent, attributed to water absorption that compromises radiative processes.