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High‐pressure torsion of SiO 2 quartz sand: Phase transformation, optical properties, and significance in geology
Author(s) -
Wang Qing,
Edalati Kaveh,
Fujita Ikuro,
Watanabe Motonori,
Ishihara Tatsumi,
Horita Zenji
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17362
Subject(s) - coesite , quartz , materials science , mineralogy , stishovite , nanocrystalline material , phase (matter) , composite material , geology , chemistry , nanotechnology , paleontology , organic chemistry , eclogite , subduction , tectonics
Phase transformation and optical properties of silica (silicon dioxide, SiO 2 ) quartz sand under high pressure/temperature has been of interest in geology and optical physics for many years. In this study, besides high pressure/temperature, high plastic strain is simultaneously applied to the quartz sand by high‐pressure torsion (HPT) processing. The material shows oxygen vacancy formation and transformation to (a) a denser nanocrystalline quartz phase, (b) a high‐temperature amorphous phase and (c) a high‐pressure coesite phase. These structural and microstructural changes lead to light absorbance, electron spin resonance, photoluminscence and photocatalytic activity, while these changes are enhanced by increasing strain. This study introduces a possible pressure‐temperature‐strain‐based mechanism for the formation of naturally observed vacancies and coesite phase in SiO 2 ‐based minerals and sands.