Abstract
Phase transformations in squaric acid (H 2C 4O 4) have been investigated by thermogravimetry and differential scanning calorimetry with different heating rates β. The mass loss in TG apparently begins at onset temperatures T di=245±5°C (β=5°C min -1), 262±5°C (β=10°C min -1), and 275±5°C (β=20°C min -1). A polymorphic phase transition was recognized as a weak endothermic peak in DSC around 101°C (T c +). Further heating with β=10°C min -1 in DSC revealed deviation of the baseline around 310°C (T i), and a large unusual exothermic peak around 355°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.
Original language | English |
---|---|
Pages (from-to) | 890-895 |
Number of pages | 6 |
Journal | Journal of Physics and Chemistry of Solids |
Volume | 73 |
Issue number | 7 |
DOIs | |
Publication status | Published - 2012 Jul |
Keywords
- B: Crystal growth
- C: Differential scanning calorimetry (DSC)
- C: Thermogravimetric analysis (TGA)
- C: X-ray diffraction
- D: Phase transitions
ASJC Scopus subject areas
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics