Abstract
Thermally stimulated depolarization current (TSDC) measurements were carried out for SiO2 in the amethyst form, aiming to investigate the relationship of observed current with relaxation phenomena related to quartz impurities. In addition to TSDC conventional dark procedure, photo-induced TSDC was also carried out, where the exciting light came from an Ar+ laser, tuned either at 488 nm or at 541 nm. X-ray diffraction and optical absorption measurements were used as complement for the interpretation of TSDC data. Optical absorption data, mainly in the range 400-700 nm, allow identifying the characteristic bands of amethyst as well as to relate them with TSDC and photo-induced TSDC data, leading to a relationship between absorption bands and light irradiation with selected wavelengths. These results allow determining how the formation of a TSDC band in the range 220-260 K, is affected by the light absorption, modifying the formation and the dipole orientation distribution in the samples. Results also help the verification of defects formed by Fe3+ or Fe4+ ions in the amethyst structure, as well as suggest that these defects, besides the participation in the amethyst structure as color centers, also play a role in the formation of TSDC bands, contributing for the observed effect of monochromatic light irradiation on these bands.
Highlights
Raw quartz is one of the main sources of materials for microelectronic and other high technology industries such as advanced glasses plants and optical fibers units, besides piezoelectric devices used in telecommunications[1,2,3,4]
No other material structure was detected by the X-ray diffractogram, such as iron clusters, which means that this ion is dispersed in the Amethyst crystalline structure and, as widely known, is responsible for some of its properties
It is important to mention that when the temperature was decreased with the polarization applied for some time at 170 K, usually 10 minutes, the thermally stimulated depolarization current (TSDC) peak was higher and, this was the used procedure for the results reported in this paper
Summary
Raw quartz is one of the main sources of materials for microelectronic and other high technology industries such as advanced glasses plants and optical fibers units, besides piezoelectric devices used in telecommunications[1,2,3,4]. Due to its large variety and geological origin, Brazilian quartz causes great scientific interest. There are reports on Amethyst use since the birth of civilization, where this mineral comes from Egypt, Southeast Asia, and West Europe[3]. It presents a high economical relevance, there is little scientific background on the natural reserves[5], and, this material represents a great potential to be explored
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
