Time:4:00-6:00, 8/11/2014

Place:A306, 1 West Building

Speaker:Prof. Xiaoli Tan, Associate Chair in Materials Science and Engineering of Iowa State University,U.S.A.

Title of Talk:A unique single-domain state in the 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 lead-free piezoelectric ceramic

Abstract of Talk:In this talk, in situ transmission electron microscopy (TEM) observations will be presented on the phase transitions and the evolution of domain morphologies during electrical poling in a polycrystalline ceramic of 0.5Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3.  In situ TEM experiments reveal that the grains of the original multi-domain state transform to a unique single-domain state at very moderate poling fields.  The grains under high poling fields are found multi-domained.  This transition corresponds to the formation of an orthorhombic phase with a significant elastic softening.  Combined with piezoelectric characterization on bulk samples and first principles calculation results, the structural origin for the ultrahigh piezoelectric coefficients in this ceramic is suggested to be intimately related to this single-domain state.

Invited by:Xiaobing Ren , MMRC