AUTHORS: M.Yu. Dolomatov, R.Z. Bakhtizin, S.A. Shutkova, K.F. Latyipov, Z.Z. Ishniyazov, N.H. Paymurzina, A.M. Petrov
PAGES: 74 - 80
This paper is a generalization of the authors’ works in the ﬁeld of asphaltene physics fulﬁlled in recent years. Speciﬁc features of the "insulator-semiconductor" phase transition in high-boiling hydrocarbon fractions are discussed. It is shown that the active resistance of the samples decreases with heating to (65 − 85)oC. At the same time, the concentration of paramagnetic centers increases, which is conﬁrmed by the EPR. The growth of electrical conductivity in high-boiling hydrocarbon fractions containing asphaltenes is caused by the temperature generation of charge carriers – free radicals (spins) formed as a result of the rupture of weak carbon-carbon bonds in molecules weakened by conjugation with aromatic rings. The energy of rupture of such bonds is rather low and can be as low as 40 kJ/mol. All these facts conﬁrm the hypothesis of the authors that in the samples a phase transition occurs from the "insulator" state to the "semiconductor" state. The dielectric-semiconductor phase transition is also due to the generation of stable free radicals, since they are strong electron acceptors and reduce the width of the forbidden band of the material. Quantum-chemical calculations conﬁrm this hypothesis. In addition, quantum-chemical calculations of the supramolecular, molecular, and electronic structure of asphaltene nanoparticles have been carried out. An experimental study of asphaltene crystallites by the AFM method was carried out. Theoretical calculations are reasonably conﬁrmed by the AFM data.
Nanoparticles, oil asphaltenes, carbon-carbon bonds.
 S.R. Sergienko et al., High-molecular non-hydrocarbon oil compounds (Moscow: Nauka 1979) 269 p.
 K. Akbarzade et al., Oil and gas review. Shlumberger 19 (2007) 28.
 X. Murgic Molecular modeling of fractions of asphaltenes and resins in oils. In the book: Physicochemical Properties of Dispersed Systems and Oil and Gas Technologies, Ed. R.Z. Safiyeva, R.Z. Syunyaeva (M.Izhevsk: Institute of Computer Research, SRC "Regular and chaotic dynamics" 2007) 580 p.
 F.G. Unger, L.N. Andreeva Fundamental aspects of petroleum chemistry. Nature of resins and asphaltenes (Novosibirsk: Nauka 1995) 192 p.
 F.G. Unger Fundamental and applied results of investigation of oil dispersed systems( Ufa, Publ. house GUP INHP RB., 2011) 264 p.
 M.Yu. Dolomatov et al., Asphalt-resinous oligomers. Application and physicochemical properties(M.: TsNIIITneftekhim, 1992) 70 p.  M.Yu. Dolomatov et al., Electrotechnical and information systems and systems No3 (2013) 109.
 M.Yu. Dolomatov et al., Journal of Materials Science and Engineering 2 (2012) 151-157.
 S.V. Dezortsev et al., Chemical Technology, 3 (2012) 88.
 M.Yu. Dolomatov et al., Materials Science 10 (2015) 3.
 M.Yu. Dolomatov et al., IOP Conf. Series: Materials Science and Engineering 195 (2017) 012005.
 M.Yu. Dolomatov et al., Journal of Materials Science and Engineering B 3 (2013) 183.
 M.Yu. Dolomatov et al., Petrochemistry 52, 4 (2012) 299.
 M.Yu. Dolomatov et al., Journal of Structural Chemistry 53, 3 (2012) 569.
 A.M. Petrov et al., Inorganic Materials: Applied Research 7,4 (2016) 453.
 M.U. Dolomatov et al., Magnetic Resonance in Solids, Electronic Journal 18,1 (2016) 1.