Some Peculiarities of Isotopic Materials Science

Abstract

The present status of the isotopetronics and its future application is briefly overviewed. Over of last five decades a great number of stable isotopes and well – developed method of their separation has made it possible to date to grow crystals of C, LiH, ZnO, ZnSe, CuCl, GaN, GaAs, CdS, Cu2 O, Si, Ge, α-Sn as well as graphene with a controllable isotopic composition. The use of such objects allows the investigate of not only the isotope effects in diffusion and lattice dynamics (vibrational, elastic and thermal properties) but also the influence of such effects on the electronic states via electron – phonon coupling (the renormalization of the band – to – band transition energy Eg as well as the exciton binding energy Eb) as well as strong nuclear force influence on elementary excitations. The thermal conductivity enhancement in the isotopically enriched materials amounts (C, Ge, Si) to almost 10% at room temperature and is close to a factor of six at the thermal conductivity maximum around 20K (Si-case). The change in the lattice constant is ∆a/a~10-3-10-4, while the change ∆cik in the elastic constants amounts to several percent. Very pronounced and general effects of isotope substitution are observed in phonon spectra. The scattering lines in isotopically mixed crystals are not only shifted (the shift of LO lines exceeds 100 cm-1) but are also broadened. Capture the thermal neutrons by isotope nuclei followed by nuclei decay produces new elements in a very large number of possibilities for isotope selective doping of different materials. Although the technology of isotopic materials science is still in its infancy, it is necessary underline that it has a very wide applications: beginning from optical fibre technology still modern development in isotope information storage and isotope quantum computers.