Dependence of acoustic anomalies on chemical composition in strontium barium niobate crystals (from conventional ferroelectric to relaxor) probed by Brillouin light scattering

Abstract

Brillouin spectra in a series of strontium barium niobate crystals Sr_xBa_1-xNb₂O₆ of different chemical composition (x = 0.3, 0.5, 0.6, 0.75) are investigated in various spectral geometries and in a wide temperature ranges including ferroelectric and paraelectric phases. It is shown that for all crystals studied, a pronounced temperature dependences of position and width of the Brillouin lines are clearly manifested only when the acoustic wave vector is parallel to the polar axis Z. Exponential temperature dependence of anomalies of elastic modules was obtained. The exponent rate decreases with increasing of disordering in crystals under study.

Keywords:

• SBN crystals
• ferroelectric phase transition
• Brillouin spectroscopy

Additional information

Funding

This work was supported by the Russian Foundation for Basic Research, projects no. 18-02-00399, 18-02-00754 and by State assignment No AAAA-A17-117052410033-9. Some part of the experiments was performed in the multiple-access center “High-Resolution Spectroscopy of Gases and Condensed Matter” in IA&E SBRAS (Novosibirsk, Russia). Growth experiments were supported by the Volkswagen Foundation Az.: 90 261 of 29th February 2017.