The Investigation Of Electronic Structure Of Pristine Carbon Compounds For Production Of New Materials Based On 13c Isotope For Neutron Converter
Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia
The creation of intensive source of high-energy neutrons based on proton accelerator is the important task of high-energy physics. The neutron producting target is a principal part of the neutron source. Materials for making the neutron target must be with high strength to high temperature. While working neutron target has took from a beam and has remove 150-200 kW at a spot 1 sm2 size during continuous process. The carbon nanomaterial containing large quantity of 13C isotope are the most perspective material for strict conditions. The aim of this work is to investigate the electronic properties of starting substance composed of 13C isotope, using the X-ray fluorescence spectroscopy, quantum chemistry calculation and conductivity measurements. From analysis of X-ray fluorescence spectra we can attain the information about material valence band structure and about electronic interaction between carbon atoms during a formation of chemical binding. The density of C2p -state for the spectrum of substance composed of 13C is increased in comparison with the spectrum of graphite. The analysis of the X-ray diffraction of the starting substance composed of 13C shows to the presence of graphite particles with 20A and 40A thickness in equal parts. Temperature dependence of a relative conductivity σ(T)/σ(300K) for 13C samples with higher density was measured. This dependence can be submitted as power one, where the power is close to 1. Such character of temperature dependence for conductivity in principal can be connected with the unelastic resonance tunneling mechanism in intercrystalline phase, or three-dimensional quantum correction to the conductivity of carbon-carbonic composite. So C150 graphen structure was modeled, and it has a size about 20A. For the proposed structure of the C150 structure quantum-chemical calculations (B3LYP method, 6-31G** basis set) were made. On the base of the result of this calculation the theoretical CKα - spectrum of the graphen was obtained. Also the theoretical CKα-spectra of the graphite was obtained taking into account carbon atoms of central hexagon of the C150 graphen. The theoretical spectrum of graphite agrees closely with the experimental one.