Characterization of (Bi0.5Na0.5)1−xBaxTiO3 grown by the TSSG method

•(Bi,Na)TiO3 transparent yellowish single crystals were grown using the TSSG method.•Driving force for the crystallization is a low evaporation of the Bi2O3/Na2O flux.•(Bi,Na)TiO3 and (Bi,Na)TiO3:Ba melt congruently near to 1290 °C.•The barium distribution coefficient is estimated to be 0.56.•The phase transitions were investigated by thermal and optical analysis.

Bi0.5Na0.5TiO3 (BNT) and (Bi0.5Na0.5)1−xBaxTiO3 (BNBT; 0.02≤xBamelt≤0.12) single crystals were grown by the Top Seeded Solution Growth (TSSG) method under conditions near to the thermodynamic equilibrium. The driving force for the crystallization process is only given by the controlled evaporation of the volatile components Bi2O3 and Na2O. The Ba-segregation coefficient in the BNBT-system was determined to be ≈0.56≈0.56 on the basis of EMPA measurements on single crystals grown from melts with a different Ba-content. Congruent melting of BNT is clearly indicated by DSC measurements at 1291 °C. BNBT behaves in a similar way whereas melting temperatures are lowered with increasing xBaxBa. cp(T)cp(T) calculations and heating/cooling polarizing microscopy was performed for the investigation of the complex domain state behavior during the phase transitions in BNT.