ИСТИНА

Materials that include radionuclides are required for beta-voltaic sources of electric current. Currently, 63Ni and tritium are considered as preferable radionuclides for a nuclear battery because its beta radiation energy is below the threshold of radiation damage of semiconductor converters. Moreover, tritium does not create radiation safety problems during operation. In this work, we applied graphene oxide as a radiation-resistant material and tritium carrier. Tritium was introduced into graphene oxide by means of tritium thermal activation method. In this method tritium atoms are generated on a tungsten wire heated by an electric current up to 2000 K and labeled substance is located at a certain distance from the wire. Since the gas pressure is low and W-wire heating intervals are short, the target material does not experience significant thermal loads. So, tritium thermal activation method allows the introduction of tritium into the material that covers the semiconductor with a thin layer without degrading its properties. The report presents the results of tritium labeling graphene oxide (Cheap Tubes) deposited on silicon substrates with titanium layer and on the glass walls of the reaction vessel. W-wire was heated to 2000 K during 20 - 60 s, then the residual gas was replaced with fresh portion of gaseous tritium. After the reaction, the graphene oxide was suspended in water, and after exposure, it was dried off under vacuum to remove tritium from the labile positions. Then graphene oxide was resuspended in 70 % nitric acid and heated to boiling point with a reverse refrigerator for 3 hours. The radioactivity of tritium was determined by liquid scintillation spectrometry by mixing an aliquot of such prepared solution with a scintillator that withstood nitric acid additives without reducing the registration efficiency. The kinetic parameters of tritium accumulation in graphene oxide are determined. It was shown that there is the first-order reaction the with an effective constant equal to 0.0027 s-1 and tritium content in graphene oxide is proportional to the available surface area. Since hydrogen substitution by tritium occurs in a thin layer of graphene oxide, the maximum specific activity was achieved when graphene oxide was distributed on the walls of the reaction vessel. Note that 22 min reaction between the atomic tritium and graphene oxide results in the specific radioactivity of 3.0 Ci/mg that exceeds the specific content of tritium in the form of titanium hydride. However, the specific radioactivity decreased to 0.5 Ci/mg when tritium was removed from the labile positions of graphene oxide, but it was still sufficient for the operation of a beta-voltaic semiconductor battery. The preparation of a composite coating of a silicon semiconductor with titanium tritide with a protective layer of nickel and tritium labeled graphene oxide as an upper layer is discussed. The work was supported by the Russian Foundation for Basic Research (Grant no. 19-08-00452).