Designing High Dielectric Permittivity Material in Barium Titanate
2017
Gao, Jinghui | Liu, Yongbin | Wang, Yan | Hu, Xinghao | Yan, Wenbo | Ke, Xiaoqin | Zhong, Lisheng | He, Yuting | Ren, Xiaobing
Developing high dielectric permittivity material is vital to satisfy the ongoing demands for the miniaturization of electronic and energy storage devices. Recent investigations uncover the role of a thermodynamical tricritical phenomenon on enhancing the dielectric response. However, such a tricritical point always locates in an extremely narrow composition region, which makes it time-consuming for exhaustive experimental searching of the optimal dielectric permittivity in a given material system. In the present paper, we employ an accelerated discovery strategy to seek the largest dielectric permittivity in Ba(Ti₁–ₓ%Hfₓ%)O₃ ceramic material by using an iterative method between computational machine learning and the experimental synthesis and property measurement. The optimal composition is found to be x = 11 with the highest permittivity of εᵣ = 4.5 × 10⁴ after 4 loops of iteration involving 6 compositions, which shows higher efficiency compared with conventional experimental searching. Further thermal analysis study suggests that such a permittivity-maximum location on the phase diagram is indeed a tricritical point. Moreover, the microstructure investigation by TEM observation indicates that the tricritical point shows a mottled morphology consisting of numerous nanodomains with multiple phases coexisting, and a phenomenological thermodynamic model based on the experimental result implies that the tricriticality is responsible for the enhanced dielectric permittivity.
显示更多 [+] 显示较少 [-]