Ultrafast Electric Field-Induced Phase Transition in Bulk Bi_0.5Na_0.5TiO₃ under High-Intensity Terahertz Irradiation

Abstract

Ultrafast polarization switching is being considered for the next generation of ferroelectric-based devices. Recently, the dynamics of the field-induced transitions associated with this switching have been difficult to explore, due to technological limitations. The advent of terahertz (THz) technology has now allowed for the study of these dynamic processes on the picosecond (ps) scale. In this paper, intense THz pulses were used as a high-frequency electric field to investigate ultrafast switching in the relaxor ferroelectric, Bi0.5Na0.5TiO3. Transient atomic-scale responses, which were evident as changes in reflectivity, were captured by THz probing. The high-energy THz pulses induce an increase in reflectivity, associated with an ultrafast field-induced phase transition from a weakly polar phase (Cc) to a strongly polar phase (R3c) within 20 ps at 200 K. This phase transition was confirmed using X-ray powder diffraction and by electrical measurements, which showed a decrease in the frequency dispersion of relative permittivity at low frequencies.

Nonlinear Optical Properties and Applications of Fluorenone Molecular Materials

“…In a number of studies it was shown that THz radiation can also efficiently manipulate properties of materials, for example inducing subpicosecond changes of the macroscopic polarisation in organic ferroelectrics, [130] a phase transition in atomic caesium vapor, [131] an ultrafast phase transition from weak polar (Cc) to strong polar (R3c) phases in ferroelectric Bi 0.5 Na 0.5 TiO 3 , [132] a THz-driven irreversible topological phase transition in two-dimensional MoTe 2, [133] and a THz induced insulator-to-metal transtion in VO 2 -based metamaterials. [134] In most of these examples reasonably strong THz fields were used.…”

Terahertz probing of low‐temperature degradation in zirconia bioceramics

“…Therefore, the higher dielectric permittivity and loss of the Non‐LTD 1700 ceramics can be attributed to a possible long distance between and in the oxygen vacancy associated () dipoles. Zhang et al 20 . have shown that a longer dipole (e.g., a longer distance between and in our samples) may produce a higher permittivity under the same AC electric field.…”

“…43 Therefore, the higher dielectric permittivity and loss of the Non-LTD 1700 ceramics can be attributed to a possible long distance between 𝑌 ′ 𝑍𝑟 and 𝑉 .. 𝑂 in the oxygen vacancy associated (𝑌 ′ 𝑍𝑟 − 𝑉 .. 𝑂 ) dipoles. Zhang et al 20 have shown that a longer dipole (e.g., a longer distance between 𝑌 ′ 𝑍𝑟 and 𝑉 .. 𝑂 in our samples) may produce a higher permittivity under the same AC electric field. The long 𝑌 ′ 𝑍𝑟 − 𝑉 .. 𝑂 distance is also related to a loosely packed structure of dipoles in the ceramic sintered at 1700…”

“…Previously, THz technology has been used to analyze biomolecules and biomaterials as it can stimulate low‐energy processes such as intra‐ and intermolecular vibrations 15–18 . THz radiation is accessible to a variety of physical properties of ceramics, such as complex refractive index and complex dielectric permittivity, making it possible to probe phase transitions of polar ceramics by the simultaneous measurement of the temperature dependencies of the dielectric permittivity and dielectric loss 19,20 . However, in bioceramics, the application of THz technology has been rarely reported.…”

Electric field-induced transformations in bismuth sodium titanate-based materials

“…The suppression of the phase transition was mainly attributed to kinetic effects and partially to the self-heating of the sample, whose temperature exponentially increased with increasing frequency and further prevented a long-range ferroelectric state to be established [221]. However, recent experiments have demonstrated that the application of THz electric field pulses of about 155 kV/cm intensity at 200 K for a time duration as short as 20 ps on BNT ceramics produces detectable changes in reflectivity, which are due to a structural transition from the monoclinic weakly polar phase Cc to the strongly polar phase R3c [222]. Although, the extent of the THz field-induced transition is lower than that driven under DC poling conditions, these results indicate that the BNT structure is also able to transform under THz irradiation [222].…”