Анотація:
The properties of internal (chemical) pressure Pi in superconducting YBa₂Cu₃O₇₋y perovskite are analytically investigated. Predicted are the values of the critical temperature Tc for the main crystallographic axes, the change of the value of dTc/dPi and the possibility to obtain YBa₂Cu₃O₇₋y samples with Tc = 166.7 K.