Study of the processes of formation of nanosized compounds in high-temperature superconductor materials upon implantation of Ba$^+$ ions

In this work, we have studied for the first time the effect of Ba ions implantation on the CuOY$_2$O$_3$BaO ceramics composition and band gap $E_g$, as well as on the number of valence electrons, by using the methods of Auger electron spectroscopy and spectroscopy of characteristic electron energy losses and by measuring energy dependences of secondary electron emission coefficient $\sigma$. It is shown that, after ion implantation, the value of $\sigma$ increases in the entire investigated range of primary electron energy $E_p$. This increase is practically independent of the substrate temperature in the range $T$ = 85–300 K. Band gap $E_g$ increases from 0.5 to 4.5 eV, which is explained by the formation of a thin ($\sim$40–50 $\mathring{\mathrm{A}}$) layer enriched with barium oxide.