Comparison between the electron paramagnetic resonance spectra obtained in X- and W-bands on a fired clay: a preliminary study

A clay was fired at 800 degrees C, which is the firing temperature generally observed in the manufacture of ancient pottery. The sample was studied by electronic paramagnetic resonance (EPR). The spectra are characteristic of Fe3+ in different environments. They were recorded at X-band (9.8 GHz) and W-band (95.5 GHz). At low temperature the amplitude of the signal, ascribed to superparamagnetic iron, decreases. In W-band and at low temperature this signal disappears almost completely. The remaining signals are ascribed to sites distribution of variable symmetries. The simplification of the spectrum obtained in W-band seems to indicate that this frequency domain is very adequate to study ancient ceramics using this technique. (C) 1999 Elsevier Science Ltd. All rights reserved.