Revised structural phase diagram of (Ba0.7Ca0.3TiO3)-(BaZr0.2Ti0.8O3)

Dean S. Keeble (1) , Feres Benabdallah (2) , Pam A. Thomas (1) , Mario Maglione (2) , Jens Kreisel (1, 3)

1 Department of Physics
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
3 Department of Science and Analysis of Materials

The temperature-composition phase diagram of barium calcium titanate zirconate (x(Ba0.7Ca0.3TiO3)-(1 − x)(BaZr0.2Ti0.8O3); BCTZ) has been reinvestigated using high-resolution synchrotron x-ray powder diffraction. Contrary to previous reports of an unusual rhombohedral-tetragonal phase transition in this system, we have observed an intermediate orthorhombic phase, isostructural to that present in the parent phase, BaTiO3, and we identify the previously assigned T-R transition as a T-O transition. We also observe the O-R transition coalescing with the previously observed triple point, forming a phase convergence region. The implication of the orthorhombic phase in reconciling the exceptional piezoelectric properties with the surrounding phase diagram is discussed.

Mots clés: Barium compounds; Calcium compounds; Critical points; Phase diagrams; Piezoceramics; Solid-state phase transformations; X-ray diffraction; Zirconium compounds

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Dean S. Keeble, Feres Benabdallah, Pam A. Thomas, Mario Maglione, Jens Kreisel. Revised structural phase diagram of (Ba0.7Ca0.3TiO3)-(BaZr0.2Ti0.8O3). Applied Physics Letters, 2013, 102 (9), pp.092903. ⟨10.1063/1.4793400⟩. ⟨hal-00808560⟩