Thermal Strain Effects in YBa 2 Cu 3 O 6+δ Superconductors

Results of the dilatometric study of superconductors with different contents of oxygen and normal phase are presented. They suggest a significant influence of the competition between strain and composition effects upon the superconducting order parameter formation and crystallographic ordering, which is revealed in anomalies on the measured temperature depcndencies of thermal strains. [Russian Text Ignored].