Crystal structure of the high temperature phase of strontium barium niobate

Abstract

Pure and undoped strontium-barium niobate Sr0:40Ba0:60Nb2O6 (SBN40) single crystals grown by the Czochralski method were investigated by single crystal X-ray diffraction methods. The study below TC (429 K for SBN40) confirmed the structure with P4bm space group. Above this temperature the structure transforms into the paraelectric, centrosymmetric one with P4=mbm space group. Analysis of the recorded diffraction patterns allowed to observe several signs of crystal structure modulation. On the registered diffraction images satellite reflections were found. A modulation vector q = ( ; ; ), where = 0:3075(6) (at room temperature) was found and it was similar to that occurring in the SBN61. In addition, above the phase transition temperature on the (hk) planes with l integer a weak diffuse scattering was observed.