Polymorphic phase transition and thermal stability in squaric acid (H2C4O4)
- Authors
- Lee, Kwang-Sei; Kweon, Jin Jung; Oh, In-Hwan; Lee, Cheol Eui
- Issue Date
- 7월-2012
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
- Keywords
- Crystal growth; Differential scanning calorimetry (DSC); Thermogravimetric analysis (TGA); X-ray diffraction; Phase transitions
- Citation
- JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS, v.73, no.7, pp.890 - 895
- Indexed
- SCIE
SCOPUS
- Journal Title
- JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
- Volume
- 73
- Number
- 7
- Start Page
- 890
- End Page
- 895
- URI
- https://scholar.korea.ac.kr/handle/2021.sw.korea/107986
- DOI
- 10.1016/j.jpcs.2012.02.013
- ISSN
- 0022-3697
- Abstract
- Phase transformations in squaric acid (H2C4O4) have been investigated by thermogravimetry and differential scanning calorimetry with different heating rates beta. The mass loss in TG apparently begins at onset temperatures T-di=245 +/- 5 degrees C (beta=5 degrees C min(-1)), 262 +/- 5 degrees C (beta=10 degrees C min(-1)), and 275 +/- 5 degrees C (beta=20 degrees C min(-1)). A polymorphic phase transition was recognized as a weak endothermic peak in DSC around 101 degrees C (T-c(+)). Further heating with beta=10 degrees C min(-1) in DSC revealed deviation of the baseline around 310 degrees C (T-i), and a large unusual exothermic peak around 355 degrees C (T-p), which are interpreted as an onset and a peak temperature of thermal decomposition, respectively. The activation energy of the thermal decomposition was obtained by employing relevant models. Thermal decomposition was recognized as a carbonization process, resulting in amorphous carbon. (C) 2012 Elsevier Ltd. All rights reserved.
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