Observation of an electromagnetically driven temperature wave in porous zinc oxide during microwave heating

Propagation of a sharp temperature wave was observed during microwave heating of porous zinc oxide in nitrogen and argon atmospheres. This wave initiated from the center of the sample and traveled at an average velocity of 0.2 cm/min towards its surface. This temperature wave was attributed to an anomalous peak in the imaginary part of the complex permittivity possibly caused by desorption of chemisorbed oxygen from the surfaces of ZnO crystallites.