Synthesis of cubic and tetragonal Ba2SmTaO6 and their optical properties after Sr doping

Abstract

Ba2–xSrxSmTaO6 has attracted great attention due to its excellent dielectric performance and abundant crystal structures. Recent studies find the reflectance of Sr–doped Ba2SmTaO6 (Ba2–xSrxSmTaO6) significantly changes with the transition between its varied phases, indicating the potential applications in optical sensors. However, its phase transition temperature (Tt) and the preparation process are not clear. In this work, the Tt between the cubic and tetragonal phases of Ba2SmTaO6 was firstly confirmed to be 533 K using self–consistent phonon theory (SCP). Combining the experimental and calculation methods, we found that the cubic and tetragonal phases of Ba2–xSrxSmTaO6 can be obtained by reacting at 1200 °C for 8 h and 1200 °C for 96 h with a low cooling rate of 2 °C/min, using the solid state reaction method, respectively. With characterizing the reflectance of different phase structures Ba2–xSrxSmTaO6, the largest reflectance difference between the tetragonal phase and cubic phase was found to be 59.22% at a wavelength of 1064 nm (wavelength commonly used in laser emitters) when x is 1.5, indicating it has great potential using in the optical sensor area. This research provides a guidance for the preparation of complex perovskite with different crystal structures of similar A2BB'O6 structure materials and is of great significance for the application of Ba2–xSrxSmTaO6 in optical sensors.