A study of the firing temperature of archeological pottery by X-ray diffraction and electron paramagnetic resonance

• Published in: The Journal of physics and chemistry of solids 2011-02, Vol.72 (2), p.90-96
• Main Authors: Mangueira, G.M., Toledo, R., Teixeira, S., Franco, R.W.A.
• Format: Article
• Language: English
• Subjects: A. Ceramics; Brazil; D. Defects; D. Electron paramagnetic resonance (EPR); Diffraction; Electron paramagnetic resonance; Firing; Iron; Kaolinite; Pottery; Thermal stability; X-rays
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2010.11.005

A fragment of an archeological funerary urn from Campos dos Goytacazes, Brazil, was studied using electron paramagnetic resonance (EPR) and X-ray diffraction (XRD). The thermal stability of all paramagnetic species was studied with isothermal treatment. In the present study, the iron signal (Fe 3+) cannot be used as a firing temperature reference for archeological pottery. The intensification of this signal with temperature is a consequence of Fe 2+ oxidation, but this reaction occurs in a short-lived treatment at high temperature or in an extended treatment at lower temperature. However, the iron signal and three other paramagnetic species indicate that the urn was fired for an extended time (up to three days). The thermal stability of the three paramagnetic species indicates a firing temperature of around 500 °C in the inner layer, between 400 and 500 °C in the middle layer, and between 500 and 800 °C in the outer layer. The presence of kaolinite structures only in the middle portion is consistent with the temperature values estimated. A firing method for the funerary archeological urn is suggested. ►Paramagnetic species were used to estimate the firing temperature of an archeological pottery. ►Information's about the technologies dominated by ancestors were obtained by EPR. ►Parameters of confection of a funerary urn of Indians were obtained by EPR and DRX. ►A firing method for a funerary archeological urn is suggested based in EPR and DRX.