Optical investigations of fluctuation of order parameter in THz range in SrxBa1-xNb2O6 crystals with different chemical compositions

摘要

Low-frequency spectra are investigated in a series of strontium barium niobate crystals SrxBa1-xNb2O6 with chemical compositions x = 0.33, 0.5, 0.61, and 0.75 in a back-scattering (ZZ) geometry and a wide temperature range including ferroelectric and paraelectric phases. It is shown that for all crystals studied, a central peak (CP) is clearly manifested in the vicinity of phase transition temperature. The temperature dependences of the CP parameters were obtained in all investigated crystals. It is shown that the central peak in all crystals studied is described by a number of relaxation times, which is typical for relaxors.