Linearni temperaturni raztezek volumenske keramike ▫$0.5Ba(Zr_{0.2}Ti_{0.8})O_3-0.5(Ba_{0.7}Ca_{0.3})TiO_3$▫ bulk ceramic

We report the linear thermal expansion coefficient of lead-free ferroelectric ceramic barium zirconate titanate - barium calcium titanate 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 (BZT-BCT). The material was prepared by solid-state synthesis and consolidated by sintering at 1450 °C. BZT-BCT crystallizes in the perovskite phase. The microstructure of the ceramic with about 95 % relative density consists of about 10 mm-sized grains. The contact dilatometry of the ceramic specimen reveals the change of slope of the linear thermal expansion curve at 84 °C. This is in good agreement with the peak of the dielectric permittivity versus temperature at about 85 °C indicating the transition from the low-temperature polar ferroelectric phase to a high-temperature nonpolar phase or Curie temperature. The thermal expansion coefficients of the polar tetragonal and nonpolar cubic phases of BZT-BCT are 7.69×10-6 K-1 (40°C – 80°C) and 12.39×10-6 K-1 (100°C – 600°C), respectively. The thermal expansion data are among the material data needed in the design of thin- and thick-film structures for energy-harvesting and energy-storage applications.