Enormous electro-optic effect in paraelectric nanodisordered KTa_1-xNbxO₃ crystal

Abstract

Recent experiments have revealed that the order of the electro-optic (EO) effect depends on the frequency of electric field in paraelectric nanodisordered KTa1-xNb x O3 (KTN) crystal. Through the dielectric frequency spectrum under the bias electric field, enormous linear and quadratic EO effects were discovered at the resonance frequencies, which changed the perception that only the quadratic EO effect exists. Applying just a small AC electric field of 6 V/mm, the effective linear EO coefficient reached 478 pm/V at 609 kHz, and the effective quadratic EO coefficient reached 4.39*10−13m2V−2at 302 kHz. The reason why an extremely low electric field results in an enormous EO coefficient is attributed to the resonance between the polar nanoregions (PNRs) and the electric field, induced by the field-driven reorientation of free dipoles on the boundary of the PNRs. In addition, the order of EO effect depending on the frequency of electric field was attributed to the motion modes of the PNR. This finding improves the understanding of how the EO effect is caused by field-driven PNR dynamics, but also provides a basis for the development of EO devices.

Cu-Doping-Modified Order State, Ferroelectric Property, Multiscale Inhomogeneities, and Local Structure in the Relaxor KTa1–xNbxO3 Crystal

“…KTa 1– x Nb x O 3 (KTN) belongs to a lead-free relaxor ferroelectric, a vital functional crystal, avoiding the pollution to the environment because of the high toxicity of lead. It has wide-ranging applications in industrial and medical fields, including electro-optic (EO) modulators, , deflectors owing to the giant EO effect and high transparency in the wide spectrum, good performance actuators, and ultrabroad-band ultrasonic imaging transducers because of excellent dielectric, piezoelectric, and electrostrictive properties . These fascinating features are closely related to polar nanoregions (PNRs) condensed by a large amount of off-center B-site Nb ions.…”

“…Further increasing the electric field, the dielectric response under a high AC electric field reflects the dynamic feature of PNR motion. It contains two effects: relaxation and resonance . Fu et al reported the inherent multiscale inhomogeneities (IMIs) in the relaxor ferroelectric Pb­(Mg 1/3 Nb 2/3 )­O 3 .…”

“…It contains two effects: relaxation 12 and resonance. 2 Fu et al reported the inherent multiscale inhomogeneities (IMIs) in the relaxor ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 . 13 The IMI nature brings novel discoveries and challenges to the application of the technology and the understanding of microstructure dynamics.…”