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Petrovskij Bryansk State University - The features of electronic, lattice, magnetic subsystems of nanostructured diborides of rare-earth elements

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Date of filling in 28.10.1997
Organization name Petrovskij Bryansk State University
Organization adress Bedjitskaya str., 14, 241036 Bryansk, Russia
Department/Unit Chair of General Physics
Contact person Novikov Vladimir, DSc, Professor
Phone +7-4832-666974
Fax +7-4832-666353
E-Mail vvnovikov@mail.ru
Web-site http://www.brgu.ru
Organization type
  • Research
  • Education
Special Programme
Theme
Nanosciences, nanotechnologies, materials and new production technologies (NMP)
Call identifier
Topic number The features of electronic, lattice, magnetic subsystems of nanostructured diborides of rare-earth elements
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Short description of the organization (max 12 lines): -
Expertise offered Diborides of rare-earth elements (RB2) is crystallized in hexagonal structure which consists of alternating close-packed layers of metal atoms and hexagonal layers of boron atoms. Such structure under certain conditions may promote a formation of two-layer nano-tubes consisting of coaxial cylindrical layers of metal and boron atoms. Until recently there is no reliable method of synthesis of single-phase rare-earth diborides, their properties practically are not investigated. The majority of rare-earth diborides at low temperatures are ferromagnetics (YbB2 is an antiferromagnetic), have metal type of electric conductivity. Samples of diborides are supposed to be synthesized in inertial atmosphere at high temperatures from elements via the intermediate hydride phase, and also with application of high pressures. The purpose of investigation is development of technologies of synthesis of RB2, determination of laws of changes of magnetic, electronic, lattice properties of RB2 with change of diboride composition and temperatures on the basis of the experimental studying of temperature dependences of heat capacity, parameters of crystal lattice, magnetic, kinetic, electrical, including thermoelectric properties of diborides in a wide temperature range (0,4 - 300 K).
Problems to be solved and results: 1. Technology of synthesis of pure phases of rare-earth diborides 2. Laws of temperature changes of heat capacity, thermal expansion coefficients, mean-square displacements of atoms in sites of crystal lattice of diborides at the temperatures 0.4-300 K 3. Values of characteristic temperatures, density of electron states at Fermi level, parameters of exchange interaction of RB2, laws of changes of the mentioned characteristics with change of rare-earth element number in Periodic system.
Scientific keywords diborides ferromagnetics heat capacity lattice dynamics phase transitions electronic properties low temperatures
Publications on the topic (other references) 1) V.V. Novikov, A.V. Matovnikov. Low-temperature Heat Capacity of Dysprosium Diboride. 9-th European Symposium on Thermoanalysis and Calorimetry, 27 – 31 August 2006, Krakov, Poland; 2) A.V.Matovnikov. Synthesis and thermodynamic properties of some diborides of rare-earth elements. Microelectronics and computer science-2006. The 13th All-Russia interuniversity scientific and technical conference of students and post-graduate students: Theses of reports. Moscow.: Moscow institute of electronic technique, 2006. - 404 p.; 3) V.V.Novikov. The lattice heat capacity of binary compounds in approach of three-dimensional Debye sublattices. Zhurnal fizicheskoj khimii, 2006, v.80 N.9, p. 1645-1649; 4) V.V.Novikov, A.V.Matovnikov. Heat capacity, enthalpy, entropy and Gibbs energy of terbium diboride on the calorimeter data in the range 5 - 300 K. Zhurnal fizicheskoj khimii, 2007, N. 4, p. 762-765; 5) V.V.Novikov, A.V.Matovnikov. Components of the low-temperature heat capacity and the magnetic phase transition of terbium diboride TbB2. Neorganicheskie materiali, 2008, v.44, N.1, p. 1-5; 6) V.V.Novikov, A.V.Matovnikov, T.A.Chukina, A.A.Sidorov, E.A.Kul\\\'chenkov. The low-temperature heat capacity and crystal lattice dynamics of yttrium diboride. Fizika tverdogo tela, 2007, v.49, N.11, 1941-1944; 7) V.V. Novikov, A.V. Matovnikov. Low-temperature Heat Capacity of Dysprosium Diboride. Journal of Thermoanalysis and Calorimetry, 2007, v.88, № 2, p. 597-599; 8) V.V. Novikov. The Phonon Heat Capacity of Rare Earth Diborides: the Approximation of Interacting Sublattices. European Symposium on Boron and Related Compounds Euroboron 4, 2-6 September 2007, Bremen: Theses of reports, p. 129. 9) V.V. Novikov, A.V. Matovnikov. Synthesis, thermodynamic and magnetic properties of holmium diboride HoB2 in a temperature interval 2 – 300 K. European Symposium on Boron and Related Compounds Euroboron 4, 2-6 September 2007, Bremen: Theses of reports, p. 121. 10) V.V. Novikov, T.A. Chukina. X-ray investigation of lattice dynamics of dysprosium diboride at the temperatures of 4.2 – 300 K. European Symposium on Boron and Related Compounds Euroboron 4, 2-6 September 2007, Bremen: Theses of reports, p. 162.
Description of previous and present experience in International Cooperation -
Previous participation in EU’s Framework Programme projects