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

A clay was fired at 800 degrees C, which is the firing temperature generall y 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, ascribe d to superparamagnetic iron, decreases. In W-band and at low temperature th is signal disappears almost completely. The remaining signals are ascribed to sites distribution of variable symmetries. The simplification of the spe ctrum obtained in W-band seems to indicate that this frequency domain is ve ry adequate to study ancient ceramics using this technique. (C) 1999 Elsevi er Science Ltd. All rights reserved.