Specific features of electrical properties of porous biocarbons prepared from beech wood and wood artificial fiberboards

• Published in: Physics of the solid state Vol. 53; no. 2; pp. 276 - 283
• Main Authors: Popov, V. V., Orlova, T. S., Magarino, E. Enrique, Bautista, M. A., Martínez-Fernández, J.
• Format: Journal Article
• Language: English
• Published: Dordrecht SP MAIK Nauka/Interperiodica 01.02.2011; Springer
• Subjects: Comparative analysis; Diffraction; Electric properties; Graphene; Physics; Physics and Astronomy; Semiconductors; Solid State Physics; Toy industry; X-rays; Carb; Noticeable Fraction; Electrical Resistivity; Natural Wood; Medium Density Fiberboard
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783411020260

This paper reports on comparative investigations of the structural and electrical properties of biomorphic carbons prepared from natural beech wood, as well as medium-density and high-density fiberboards, by means of carbonization at different temperatures T carb in the range 650–1000°C. It has been demonstrated using X-ray diffraction analysis that biocarbons prepared from medium-density and high-density fiberboards at all temperatures T carb contain a nanocrystalline graphite component, namely, three-dimensional crystallites 11–14 Å in size. An increase in the carbonization temperature T carb to 1000°C leads to the appearance of a noticeable fraction of two-dimensional graphene particles with the same sizes. The temperature dependences of the electrical resistivity ρ of the biomorphic carbons have been measured and analyzed in the temperature range 1.8–300 K. For all types of carbons under investigation, an increase in the carbonization temperature T carb from 600 to 900°C leads to a change in the electrical resistivity at T = 300 K by five or six orders of magnitude. The dependences ρ( T ) for these materials are adequately described by the Mott law for the variable-range hopping conduction. It has been revealed that the temperature dependence of the electrical resistivity exhibits a hysteresis, which has been attributed to thermomechanical stresses in an inhomogeneous structure of the biocarbon prepared at a low carbonization temperature T carb . The crossover to the conductivity characteristic of disordered metal systems is observed at T carb ≳ 1000°C.