离子对(Nb5+-Cr3+)掺杂对0.93Bi0.5Na0.5TiO3-0.07BaTiO3陶瓷微观结构和电学性能的影响

采用固相烧结法制备(Bi_0.5Na_0.5)_0.93Ba_0.07Ti_1-x(Nb_0.5Cr_0.5)_xO₃(摩尔分数x=0%、0.5%、1%、2%、2.5%、5%)(简称BNBT-xNC)无铅压电陶瓷,研究离子对(Nb⁵⁺-Cr³⁺)对0.93Bi_0.5Na_0.5TiO₃-0.07BaTiO₃(简称BNT-7BT)陶瓷微观结构、介电、铁电和应变性能的影响。结果表明,所有组分为伪立方相。随着离子对(Nb⁵⁺-Cr³⁺)含量增加,BNBT-xNC陶瓷的铁电弛豫特性明显改变,在较低掺杂浓度下(0%≤x≤1%)为非遍历弛豫态,随含量增加(1%≤x≤2%),出现非遍历-遍历弛豫态共存,最后转变为遍历弛豫态(2.5%≤x≤5%);陶瓷从铁电态向弛豫态转变,应变性能先增加后降低,最大应变S_max和逆压电常数d^*₃₃在x=2%时达到最大,分别为0.22%和431 pm/V。

Effect of Ionic Pair (Nb5+-Cr3+) Doping on Microstructure and Electrical Properties of 0.93Bi0.5Na0.5TiO3-0.07BaTiO3 Ceramics

A new promising lead-free piezoelectric ceramics (Bi_0.5Na_0.5)_0.93Ba_0.07Ti_1-x(Nb_0.5Cr_0.5)_xO₃ (mole fraction x=0%, 0.5%, 1%, 2%, 2.5%, 5%) (abbreviated as BNBT-xNC) were prepared by the conventional solid-phase synthesis method. The effect of ionic pair (Nb⁵⁺-Cr³⁺) on microstructures, dielectric properties, and ferroelectric properties as well as strain properties of 0.93Bi_0.5Na_0.5TiO₃-0.07BaTiO₃ (abbreviated as BNT-7BT) ceramics was systematically investigated. The results show that all composition exhibits a single pseudo-cubic structure. The electrical properties reveal that the ferroelectric relaxor characteristics of BNBT-xNC ceramics change significantly with different ionic pair (Nb⁵⁺-Cr³⁺) substitution. The increasing ionic pair (Nb⁵⁺-Cr³⁺) modification induces two transitions from non-ergodic relaxor state (0%≤x≤1%) to coexistence of non-ergodic-ergodic relaxor state (1%≤x≤2%), and finally to ergodic relaxor state (2.5%≤x≤5%). The ionic pair (Nb⁵⁺-Cr³⁺) modification induces BNBT-xNC ceramics transition from ferroelectric state to relaxor state, and strain properties first increase and then decrease. A low dose of ionic pair (Nb⁵⁺-Cr³⁺) substitution enhances the strain propertites of BNBT-xNC ceramics, and the BNBT-xNC ceramics with x=2% exhibits the maximum strain (S_max=0.22%) and inverse piezoelectric constant (d^*₃₃=431 pm/V). The evolution of electrical properties associates with micostucture, which provides a new sight to investigate the effect of the ionic pair doping on BNT-BT ceramics.