Unraveling the mystery of the tricritical point in Zr-rich PbZr1-xTixO3

The solid solution of lead titanate (PbTiO3) and lead zirconate (PbZrO3), known as PbZr1-xTixO3 (PZT), is commonly used in a wide range of applications because of its high piezoelectric and coupling coefficient. The morphotropic phase boundary (MPB) has been widely studied by lots of researchers including us. Recent study shows tricritical behaviour in the high-Zr (x ~ 0.06) region. Unusual anomalies have been observed with Curie temperature, dielectric constants etc. as a function of composition. Our recent diffuse scattering results on single crystals suggest that the structure here is of lower symmetry than previously thought. In order to investigate the high-temperature and room-temperature structures and phase changes around this tricritical point, we request four days of HRPD time to collect full patterns with x = 0.02, 0.04, 0.05, 0.06, 0.07, 0.08, 0.10 at various temperatures.

钛酸铅（PbTiO₃）与锆酸铅（PbZrO₃）所形成的固溶体，其化学式为PbZr₁₋ₓTiₓO₃（简称PZT），凭借优异的压电性能与耦合系数，被广泛应用于诸多领域。包括本团队在内的诸多研究者已对该材料的准同型相界（morphotropic phase boundary, MPB）开展了大量研究工作。近期研究表明，在高锆含量（x≈0.06）区域存在三临界行为，且观测到居里温度、介电常数等物性随组分变化出现异常现象。本团队近期针对单晶的漫散射研究结果显示，该区域的结构对称性较此前学界的认知更低。为探究该三临界点附近的高温与室温结构及相变行为，本团队申请4天的高分辨粉末衍射（HRPD）机时，以在不同温度下采集x分别为0.02、0.04、0.05、0.06、0.07、0.08、0.10的完整衍射图谱。