Peculiarities of Ferroelectric Phase Transition in (Ba, Sr) TiO3 Heteroepitaxial Films Obtained by HF Cathode Sputtering

It is shown that in (Ba, Sr) TiO3 films on (001) MgO mechanical stresses of two‐dimensional equiaxial compression exist, gaining in strength with increasing the film thickness and degree of coherence of film lattice and substrate. These stresses determine a series of peculiaritics in the phase transitions observed experimentally in (Ba, Sr) TiO3 heteroepitaxial films, such as the significant increase of Curie point temperature and the smoothing of the dependence of the tangential dielectric permittivity on temperature in the vicinity of this point with increasing film thickness, the lowering of tetragonal‐monoclinic (rhombic when lacking stresses) phase transition in thick films, etc. [Russian Text Ignored].