Phase Transitions in Two- and Three-Component
Perovskite Superlattices

Yu. A. Tikhonov^a, A. G. Razumnaya^{a, b}, O. A. Maslova^a, I. N. Zakharchenko^a,
Yu. I. Yuzyuk^a, *, N. Ortega^c, A. Kumar^c, and R. S. Katiyar^c

^a Southern Federal University, ul. Bolshaya Sadovaya 105/42, Rostov-on-Don, 344006 Russia

* e-mail: yuzyuk@rambler.ru

^b Laboratoire de Physique de la Matiére Condensé (LPMC), Université@ de Picardie Jules Verne,
33 rue Saint Leu, Amiens, 80039 France

^c University of Puerto Rico, Avenida Barbosa y Avenida Juan Ponce De León,
San Juan, Puerto Rico, 00931 United States

Abstract—The temperature behavior of polarization Raman spectra of two-layer BaTiO₃/Ba_0.5Sr_0.5TiO₃ and
three-layer BaTiO₃/Ba_0.5Sr_0.5TiO₃/SrTiO₃ superlattices prepared by pulsed laser deposition on (001)MgO sub-
strates has been studied. It has been found that, at room temperature, the frequency of soft mode E(TO) in the
three-layer superlattice is significantly higher (94 cm^–1) than that in the two-layer superlattice (70 cm^–1), which
demonstrates an increase in two-dimensional stresses in epitaxial layers of the superlattice. An analysis of the
temperature dependence of the integrated intensity of soft mode E(TO) suggests that the BaTiO₃/Ba_0.5Sr_0.5TiO₃
superlattice undergoes a transition from the ferroelectric to paraelectric phase at ~540K, and the phase transi-
tion temperature of the BaTiO₃/Ba_0.5Sr_0.5TiO₃/SrTiO₃ superlattice increases to ~610 K because of the deforma-
tion of the epitaxial layers.

DOI: 10.1134/S1063783415030336

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