III International Conference

PP-I-8It was established that spectrum width of ACM-4 is 2.5 G at both 77 and 300 K. ACM-6has no EPR spectra. EPR spectra of ACM-6 sample shows correlation with Curie law and hasspectrum width 23 G at 293 K and 4 G at 77 K.Low concentration of carriers of a current in an amorphous carbon material leads tosuppression of metal conductivity and to localization electron conductivity in the limited areaof space. In this case hopping conductivity between these areas of localization. changes tohopping conductivity with variable length of a jump and described by generalized Mottlow[4]:σ (T) = σ 0 •exp(-B/T) 1/(d+1)T,°CTime, minConditions of synthesis and calculated value of electronic conductivity at 300 KACM-1 ACM-2 ACM-3 ACM-4 ACM-5 ACM-6900237001590015σ(300K) 0.0550232 1.0618365 4.9530324 0.0002388 0.7891491 0.337564d 3 1 1 1 1 1d – dimension of movement of current carriers, B = [16a 3 /k Б N(E F )], a – inverse value oflength where the amplitude of nuclear wave function falls down (usually 1/a ~ 8÷10 Å), N(E F )– density of conditions on surface Fermi, σ 0 – constant.In all temperature interval electronic conductivity described by Mott low for onedimensionalsystems (d=1) in spite of temperature dependence conductivity of ACM-4 –ACM-6 samples are notably different. It is necessary to note that the one-dimensionalconductivity was already observed in carbon structures with carbin chains [5 - 7], andtemperature dependence of conductivity had similar character.As indicated in the table the conductivity of the samples depends on duration andtemperature of heat treatment. The sample has three-dimensional conductivity if duration ofheat treatment at 900 °C more than 15 minutes (ACM-1). If duration of heat treatment at900 °C less than 15 minutes, one-dimensional conductivity of sample grows. For example,heat treatment of ACM-4 at 900 °C within 10 minutes leads to increasing the sampleconductivity by three orders and broadening of the EPR spectra (ACM-5). EPR spectra ofACM-2 and ACM-3 samples do not show correlation with Curie law. It may be connectedwith the presence of undercondensed carbon systems (e.g.coke-type) giving EPR spectra. Itmay be assumed that in order to undercondensed carbon systems disappear more highertemperature or more duration of treatment is needed for phenol and 1,2,3-benzotriazolmixture than for nitroaniline and 1,2,3-benzotriazol mixture.70020900107008021