• Characterization of microwave and terahertz dielectric properties of single crystal La2Ti2O7 along one single direction

      Zhang, Man; orcid: 0000-0002-1094-7279; Tang, Zhiyong; orcid: 0000-0002-1921-6034; Zhang, Hangfeng; Smith, Graham; orcid: 0000-0003-3273-7085; Jiang, Qinghui; Saunders, Theo; orcid: 0000-0003-4250-3071; Yang, Bin; Yan, Haixue; orcid: 0000-0002-4563-1100
      New generation wireless communication systems require characterisations of dielectric permittivity and loss tangent at microwave and terahertz bands. La2Ti2O7 is a candidate material for microwave application. However, all the reported microwave dielectric data are average value from different directions of a single crystal, which could not reflect its anisotropic nature due to the layered crystal structure. Its dielectric properties at the microwave and terahertz bands in a single crystallographic direction have rarely been reported. In this work, a single crystal ferroelectric La2Ti2O7 was prepared by floating zone method and its dielectric properties were characterized from 1 kHz to 1 THz along one single direction. The decrease in dielectric permittivity with increasing frequency is related to dielectric relaxation from radio frequency to microwave then to terahertz band. The capability of characterizing anisotropic dielectric properties of a single crystal in this work opens the feasibility for its microwave and terahertz applications.
    • Characterization of microwave and terahertz dielectric properties of single crystal La2Ti2O7 along one single direction

      Zhang, Man; orcid: 0000-0002-1094-7279; Tang, Zhiyong; orcid: 0000-0002-1921-6034; Zhang, Hangfeng; Smith, Graham; orcid: 0000-0003-3273-7085; Jiang, Qinghui; Saunders, Theo; orcid: 0000-0003-4250-3071; Yang, Bin; Yan, Haixue; orcid: 0000-0002-4563-1100 (Elsevier, 2021-08-27)
      New generation wireless communication systems require characterisations of dielectric permittivity and loss tangent at microwave and terahertz bands. La2Ti2O7 is a candidate material for microwave application. However, all the reported microwave dielectric data are average value from different directions of a single crystal, which could not reflect its anisotropic nature due to the layered crystal structure. Its dielectric properties at the microwave and terahertz bands in a single crystallographic direction have rarely been reported. In this work, a single crystal ferroelectric La2Ti2O7 was prepared by floating zone method and its dielectric properties were characterized from 1 kHz to 1 THz along one single direction. The decrease in dielectric permittivity with increasing frequency is related to dielectric relaxation from radio frequency to microwave then to terahertz band. The capability of characterizing anisotropic dielectric properties of a single crystal in this work opens the feasibility for its microwave and terahertz applications.
    • Multiscale understanding of electric polarization in poly(vinylidene fluoride)-based ferroelectric polymers

      Meng, Nan; orcid: 0000-0002-7609-0407; Ren, Xintong; orcid: 0000-0003-2472-4866; Zhu, Xiaojing; orcid: 0000-0001-8947-1658; Wu, Jiyue; orcid: 0000-0002-0827-2831; Yang, Bin; orcid: 0000-0001-5620-9506; Gao, Feng; orcid: 0000-0002-5075-4076; Zhang, Han; orcid: 0000-0002-0479-224X; Liao, Yaozu; orcid: 0000-0001-9263-6281; Bilotti, Emiliano; orcid: 0000-0003-3952-1148; Reece, Michael J.; et al. (Royal Society of Chemistry (RSC), 2020)
      The electric polarization of ferroelectric polymers with tailored structures was studied using the terahertz time-domain spectroscopy technique combined with impedance analysis.
    • Multiscale understanding of electric polarization in poly(vinylidene fluoride)-based ferroelectric polymers

      Meng, Nan; orcid: 0000-0002-7609-0407; Ren, Xintong; orcid: 0000-0003-2472-4866; Zhu, Xiaojing; orcid: 0000-0001-8947-1658; Wu, Jiyue; orcid: 0000-0002-0827-2831; Yang, Bin; orcid: 0000-0001-5620-9506; Gao, Feng; orcid: 0000-0002-5075-4076; Zhang, Han; orcid: 0000-0002-0479-224X; Liao, Yaozu; orcid: 0000-0001-9263-6281; Bilotti, Emiliano; orcid: 0000-0003-3952-1148; Reece, Michael J.; et al. (Royal Society of Chemistry (RSC), 2020)
      The electric polarization of ferroelectric polymers with tailored structures was studied using the terahertz time-domain spectroscopy technique combined with impedance analysis.
    • Terahertz Characterization of Lead-Free Dielectrics for Different Applications

      Zhang, Man; Zhang, Hangfeng; Jiang, Qinghui; orcid: 0000-0001-7851-2653; Gao, Feng; orcid: 0000-0002-5075-4076; Chen, Riqing; Zhang, Dou; orcid: 0000-0001-8555-2784; Reece, Michael John; orcid: 0000-0002-2293-7123; Yang, Bin; Viola, Giuseppe; Yan, Haixue; orcid: 0000-0002-4563-1100 (American Chemical Society (ACS), 2021-11-02)
    • Terahertz Characterization of Lead-Free Dielectrics for Different Applications

      Zhang, Man; Zhang, Hangfeng; Jiang, Qinghui; orcid: 0000-0001-7851-2653; Gao, Feng; orcid: 0000-0002-5075-4076; Chen, Riqing; Zhang, Dou; orcid: 0000-0001-8555-2784; Reece, Michael John; orcid: 0000-0002-2293-7123; Yang, Bin; Viola, Giuseppe; Yan, Haixue; orcid: 0000-0002-4563-1100 (American Chemical Society (ACS), 2021-11-02)
    • Terahertz Characterization of Lead-Free Dielectrics for Different Applications.

      Zhang, Man; Zhang, Hangfeng; Jiang, Qinghui; orcid: 0000-0001-7851-2653; Gao, Feng; orcid: 0000-0002-5075-4076; Chen, Riqing; Zhang, Dou; orcid: 0000-0001-8555-2784; Reece, Michael John; orcid: 0000-0002-2293-7123; Yang, Bin; Viola, Giuseppe; Yan, Haixue; orcid: 0000-0002-4563-1100 (2021-11-02)
      In this spotlight on applications, we describe our recent progress on the terahertz (THz) characterization of linear and nonlinear dielectrics for broadening their applications in different electrical devices. We begin with a discussion on the behavior of dielectrics over a broadband of frequencies and describe the main characteristics of ferroelectrics, as they are an important category of nonlinear dielectrics. We then move on to look at the influence of point defects, porosities, and interfaces, including grain boundaries and domain walls, on the dielectric properties at THz frequencies. Based on our studies on linear dielectrics, we show that THz characterization is able to probe the effect of porosities, point defects, shear planes, and grain boundaries to improve dielectric properties for telecommunication applications. Further, we demonstrate that THz measurements on relaxor ferroelectrics can be successfully used to study the reversibility of the electric field-induced phase transitions, providing guidance for improving their energy storage efficiency in capacitors. Finally, we show that THz characterization can be used to characterize the effect of domain walls in ferroelectrics. In particular, our studies indicate that the dipoles located within domain walls provide a lower contribution to the permittivity at THz frequencies than the dipoles present in domains. The new findings could help develop a new memory device based on nondestructive reading operations using a THz beam.
    • Terahertz Reading of Ferroelectric Domain Wall Dielectric Switching

      Zhang, Man; Chen, Zhe; Yue, Yajun; Chen, Tao; Yan, Zhongna; Jiang, Qinghui; Yang, Bin; Eriksson, Mirva; Tang, Jianhua; Zhang, Dou; orcid: 0000-0001-8555-2784; et al. (American Chemical Society (ACS), 2021-03-09)
    • Ultrafast Electric Field-Induced Phase Transition in Bulk Bi0.5Na0.5TiO3 under High-Intensity Terahertz Irradiation

      Zhang, Man; McKinnon, Ruth A.; Viola, Giuseppe; Yang, Bin; Zhang, Dou; orcid: 0000-0001-8555-2784; Reece, Michael J.; orcid: 0000-0002-2293-7123; Abrahams, Isaac; orcid: 0000-0002-8606-6056; Yan, Haixue; orcid: 0000-0002-4563-1100 (American Chemical Society (ACS), 2020-12-10)