  The remarkable finding of this work is the linear correlation between the
critical temperature of superconducting (SC) transition, Tc, and the
room-temperature half-width of angular correlation of positron annihila- tion
phonons (ACPAP), Go/2, in the series of powder samples of high-Tc YBCO(123)
ceramic superconductors (SCs) with various deficiency of oxygen content. This
correlation points to the existence of fundamental physical parameter of
materials in all-temperature range,which is the crucial one for their
insulator-metal-superconductor (IMSC) transition. We attribute this
key-parameter to the rapid increase and then the steady (due to the minimal
mechanical relaxation rate) lattice compressive deformation - the sudden and
stable jump in work-hardening of crystals). The traces of this compression may
be observed by different methods over a wide range of te- mperatures and used
for the forecast of the parameters of technological interest for the new SCs.
