铋系化合物改性的新型三元弛豫铁电体的性能研究

钛酸钡(BaTiO₃)陶瓷作为传统的介质电容器材料,其强铁电性会导致储能密度低下,但通过掺杂可以削弱铁电性来获得弛豫铁电体,提高储能性能。利用铋系化合物可增强弛豫特性,本文设计了BiScO₃和(Sr_0.7Bi_0.2)TiO₃取代改性的BaTiO₃基三元陶瓷材料: (0.99-x)Ba(Zr_0.1Ti_0.9)O₃-x(Sr_0.7Bi_0.2)TiO₃-0.01BiScO₃(缩写为BZT-xSBT-BS)。采用传统固相法制备的BZT-xSBT-BS陶瓷,相结构没有因为掺杂发生改变,在室温下均为纯的三方相钙钛矿结构。介电和铁电的测试与分析表明,BZT-xSBT-BS陶瓷具有典型的弛豫铁电特性。由于不等价离子Sr²⁺、Bi³⁺的掺杂导致界面松弛极化,可以增大BZT-xSBT-BS陶瓷的介电常数,但是受制于其慢的响应速度,陶瓷的介电损耗也显著增加。适量(Sr_0.7Bi_0.2)TiO₃可以提升BZT-xSBT-BS陶瓷的介电、铁电、应变和储能性能,x=0.015时的BZT-xSBT-BS陶瓷的综合性能较优:ε_r~10 372,tanδ~0.019,P_max=16.42 μC/cm²,E_c=1.41 kV/cm,S⁺_max=0.12%(@40 kV/cm),W_D=0.181 J/cm³,η=80.4%(@60 kV/cm)。

Properties of Novel Ternary Relaxor Ferroelectrics Modified by Bismuth Series Compounds

As a traditional dielectric capacitor material, barium titanate (BaTiO₃) ceramics have strong ferroelectric property, which leads to low energy storage density. However, the relaxation ferroelectric can be obtained through doping to weaken the ferroelectric property and improve the energy storage performance. In this paper, BaTiO₃-based ceramics modified by BiScO₃ and (Sr_0.7Bi_0.2)TiO₃, a ternary ceramic material (0.99-x)Ba(Zr_0.1Ti_0.9)O₃-x(Sr_0.7Bi_0.2)TiO₃-0.01BiScO₃(abbreviated as BZT-xSBT-BS) was designed, owing to the enhanced relaxation properties induced by bismuth series compounds. The phase structure of BZT-xSBT-BS ceramics prepared by traditional solid-state method is not changed due to doping, and they are pure cubic perovskite structure at room temperature. Dielectric and ferroelectric tests and analysis show that BZT-xSBT-BS ceramics have typical relaxor ferroelectric properties. Sr²⁺ and Bi³⁺ ions substitutions produce thermionic relaxation polarization, which contributes to the polarization and increases the dielectric constant of BZT-xSBT-BS ceramics, but the dielectric loss will increase due to its slow response speed. An appropriate amount of (Sr_0.7Bi_0.2)TiO₃ can improve the dielectric, ferroelectric, strain and energy storage properties of BZT-xSBT-BS ceramics. BZT-xSBT-BS ceramics with x=0.015 show excellent properties, ε_r~10 372, tanδ~0.019, P_max=16.42 μC/cm², E_c=1.41 kV/cm, S⁺_max=0.12% (@40 kV/cm), W_D=0.181 J/cm³, η=79.4% (@60 kV/cm).