Study on the visible-light absorption of quartz with different valence states of iron

Abstract

In order to study the effect of impurity iron in different valence states on the coloration mechanism of quartz, colorless synthetic quartz fabricated via ion implantation and its natural counterpart citrine with iron were compared after heating under different atmospheres. Ultraviolet-visible spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, and Fourier transform infrared spectroscopy were used to analyze the absorption property, valence states of iron, and type of O of both natural citrine and ion-implanted quartz. Experimental results showed the yellow color in quartz was mainly related to the charge transfer between Fe³⁺ and Fe²⁺, oxygen vacancies and the lattice oxygen, whereas the pink color in quartz was related to oxygen vacancies at a high temperature of 1200 °C.