Optimized hybrid improper ferroelectricity of (Ca1-Nd )3Ti2O7 ceramics based on soft doping effects

Low remnant polarization and high coercive field are the main factors limiting the practical application of Ca3Ti2O7-based hybrid improper ferroelectric ceramics. Based on sol-gel method and soft doping effect, (Ca1-xNdx)3Ti2O7 (x=0.003) ceramics with higher remnant polarization of ∼3.53 μC/cm2 and lower coercive field of ∼91 kV/cm were obtained. More interestingly, thanks to the large distortion amplitude of TiO6 octahedron and effective suppression of defects such as oxygen vacancies caused by Nd3+ as a donor dopant, the remnant polarization of (Ca1-xNdx)3Ti2O7 (x = 0.003 and 0.006) ceramics measured at 10 Hz using the DHM mode were as high as 7.33 μC/cm2 and 5.85 μC/cm2. These findings prove that the soft doping at A sites of Ca3Ti2O7 material is a simple and effective strategy to enhance its hybrid improper ferroelectricity.