Thermomechanical response of polycrystalline BaZrO3

Thermomechanical properties of fine-grained, 96% dense, polycrystalline BaZ rO3 specimens were studied. The average thermal expansion coefficient of Ba ZrO3 at 25-1000 degrees C was 7.72 x 10(-6)degrees C-1. At 25 degrees C, Yo ung's modulus was 240.5 GPa and the shear modulus was 97.2 GPa. These value s decreased by approximate to 10% with heating to 1015 degrees C. Poisson's ratio was 0.237 and was independent of temperature. The BaZrO3 specimens e xhibited a thermal expansion coefficient of about one half, and elastic mod uli more than twice, those of polycrystalline high-temperature superconduct ors. Diffusional creep was observed when BaZrO3 was compressed at 1300-1400 degrees C; the activation energy for steady-state deformation was 460 +/- 30 kJ/mole. The mechanism was probably grain-boundary sliding, controlled b y diffusion of one of the cations along grain boundaries. Deformation rates below 1000 degrees C were too low to relax thermally generated stresses. P ublished by Elsevier Science B.V.