Study of the soft mode behavior of doped and mixte BaTiO³ single crystals by I.R. reflectometry

Abstract

Infrared reflectivity measurements are performed with a scanning interferometer on single crystals of Fe-doped barium titanate and Ba₀₉ Sr₀₁TiO₃ solid solution, over a wide range of temperature in the paraelectric phase. Comparisons with results obtained on undoped BaTiO₃ show that a substitution of 10% Sr in the barium site shifts up the soft mode frequency whereas substitution of 0.4% Fe in the Ti site does not significantly alter the soft mode behavior. The role played by impurities on the mechanism which drives the FE-PE transition is then discussed. (31 ref).