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Title: Infrared spectra of silica polymorphs and the conditions of their formation

The existence of silica within several debris disks has been suggested. Data on both the spectroscopy and annealing conditions of the various polymorphs of silica need to be investigated, as these data are lacking and incomplete in the literature. We investigate the annealing conditions of silica and prepare various types of silica, including α-cristobalite, α-quartz, coesite, stishovite, and fused quartz, which are natural, synthetic, or commercial samples. This paper presents a new study of both the spectroscopy of relevant silica polymorphs and the conditions under which they form. We compare the results to previous studies and find that there are discrepancies. The interesting result of features similar to those of forsterite should be highlighted, where α-cristobalite and coesite showed similar peaks at 16, 33, and 69 μm as forsterite. The 69 μm band for α-cristobalite is especially very broad and strong and shifts largely to a shorter wavelengths under cooling to low temperatures. The band for coesite, however, is very sharp and shifts only a small amount to longer wavelengths under cooling to low temperatures. We discuss the possibility of silica detection around debris disks.
Authors:
 [1] ; ; ; ;  [2] ; ;  [3] ;  [4]
  1. Department of Physics, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan)
  2. Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)
  3. Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-8052 (Japan)
  4. National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)
Publication Date:
OSTI Identifier:
22341982
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANNEALING; COMPARATIVE EVALUATIONS; COSMOLOGY; CRISTOBALITE; DETECTION; INFRARED SPECTRA; QUARTZ; SILICA; SILICON OXIDES; SOLIDS; SPECTROSCOPY; STARS; STISHOVITE; WAVELENGTHS