Thermal expansion of SrxBa1-xNb2O6 across and above the ferroelectric phase transition

Lead-free SrxBa1-xNb2O6(SBN) is of interest due to flexible chemistry, ferroelectric behavior, and electro-optic properties. The thermal expansion coefficient for SBN is reported only for compositions x = 0.35-0.59 and temperature range 20-50 degrees C, and for x = 0.5 composition up to 500 degrees C. Here, X-ray diffraction of Sr0.4Ba0.6Nb2O6 (SBN40), Sr0.5Ba0.5Nb2O6 (SBN50) and Sr0.6Ba0.4Nb2O6 (SBN60) is reported in the temperature range up to 930 degrees C. The thermal expansion is anisotropic, differing significantly for the a and c lattice parameters, and a larger variation in the thermal expansion of the c lattice parameters was observed as a function of composition. Above the Curie temperature, the thermal expansion coefficient is decreasing with increasing temperature and decreasing Sr content. Linear thermal expansion coefficients range from 11.45(5) to 7.90(3)& sdot;10-6 K-1 for the a lattice parameter and 9.10(1) to 4.40(1)& sdot;10-6 K-1 for the c lattice parameter depending on composition and temperature range.