P Vineetha, Jose Roshan, Saravanan K Venkata
Department of Physics, School of Basic and Applied Sciences, Central University of Tamil Nadu Thiruvarur-610005 India
RSC Adv. 2019 Oct 29;9(60):34888-34895. doi: 10.1039/c9ra06526a. eCollection 2019 Oct 28.
This work investigates and reports the effect of ZnO addition on the ferroelectric properties of (KNa)(NbTa)O (KNNT) ceramics prepared by a solid state reaction method. Though literature is abundant on the study of the effect of ZnO on the sinterability, microstructure and electrical properties of KNN based materials, the effect of ZnO on their ferroelectric properties has seldom been studied in detail, especially in KNNT. In the current study, 2, 4 and 6 wt% of ZnO was added to KNNT ceramics. The XRD results revealed ZnO addition has no effect on the crystal symmetry of KNNT. However, a ZnO secondary phase was found in KNNT ceramics with 4 and 6 wt% ZnO doping. An increase in grain size was observed with increases in the concentration of ZnO, indicating a direct dependence of grain size on the concentration of ZnO in the KNNT matrix. From ferroelectric studies it was observed that a lower electric field was sufficient to get maximum polarization for ZnO doped KNNT samples compared to that of pure KNNT ceramics. A high remnant polarization ( = 14.0 μC cm) and lower coercive field ( = 5.6 kV cm) was obtained for 2 wt% ZnO doped KNNT. These samples showed the least fatigue (0.8%) after 10 cycles in comparison to pure (5%), 4 wt% ZnO doped (24.9%) and 6 wt% ZnO doped (30%) KNNT ceramics. The diminution in , , and was only 26.0%, 26.2% and 18.5%, respectively, with an increase in measurement temperature, which indicates improved thermal stability in 2 wt% ZnO doped KNNT. From the present study the optimum concentration of ZnO in KNNT is identify to be 2.0 wt% and their improved properties in comparison to the pure KNNT ceramics are discussed in detail.
本工作研究并报道了添加ZnO对采用固态反应法制备的(KNa)(NbTa)O（KNNT）陶瓷铁电性能的影响。尽管关于ZnO对KNN基材料的烧结性、微观结构和电学性能影响的研究文献众多，但ZnO对其铁电性能的影响很少被详细研究，尤其是在KNNT中。在当前研究中，向KNNT陶瓷中添加了2 wt%、4 wt%和6 wt%的ZnO。XRD结果表明，添加ZnO对KNNT的晶体对称性没有影响。然而，在掺杂4 wt%和6 wt% ZnO的KNNT陶瓷中发现了ZnO第二相。随着ZnO浓度的增加，观察到晶粒尺寸增大，这表明晶粒尺寸与KNNT基体中ZnO的浓度直接相关。从铁电研究中观察到，与纯KNNT陶瓷相比，掺杂ZnO的KNNT样品在较低电场下就能获得最大极化。对于掺杂2 wt% ZnO的KNNT，获得了高剩余极化（(Pr = 14.0 μC/cm^2)）和低矫顽场（(Ec = 5.6 kV/cm)）。与纯KNNT（5%）、掺杂4 wt% ZnO（24.9%）和掺杂6 wt% ZnO（30%）的KNNT陶瓷相比，这些样品在10次循环后显示出最小的疲劳率（0.8%）。随着测量温度的升高，(Pr)、(Ec)和(Ps)的减小分别仅为26.0%、26.2%和18.5%，这表明掺杂2 wt% ZnO的KNNT具有更好的热稳定性。从本研究中确定KNNT中ZnO的最佳浓度为2.0 wt%，并详细讨论了其与纯KNNT陶瓷相比改善的性能。
