The 0.96(Bi0.5Na0.5)TiO3 - 0.04BaTiO3 crystal structure: A high-Q, high-counting statistics synchrotron diffraction analysis

A synchrotron powder diffraction experiment, especially designed to shed light on the controversial problem of the crystal structure of 0.96(Bi0.5Na0.5)TiO3 - 0.04BaTiO3, is reported. The investigated material is a key component of the current international search for lead-free ferropiezoelectrics. A wide angular range diffraction pattern was measured in high resolution configuration, with emphasis on trustable counting stastistics in the high-Q interval. Cc and R3c structural models were tried as primary phases. The obtained experimental results are incompatible with the monoclinic model and clearly favor the rhombohedral symmetry. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.