Electrical properties of a periodic porous carbon replica of opal

The electrical conductivity and magnetoconductance of pyrolized porous phen olic resin opal replicas have been studied as a function of their heat trea tment temperature (HTT) up to 2380 degrees C. Porous graphite can be formed by pyrolizing the phenolic resin opal replica. In the case of replicas wit h a low HTT, a crossover from Mott variable range hopping (VRI I) to Efros and Shklovskii VRH upon decreasing the temperature has been experimentally observed. For those with a high HTT, the electrical properties are consiste nt with those of pyrolytic graphite. The occurrence of positive magnetocond uctance indicates the existence of quantum effect at low temperatures.