Glass-forming liquid kinetics manifested in a KTN:Cu crystal

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

“…We associate the detected temperatures T C = 282 K, T C = 202 K, and T C = 156 K with the cubic/tetragonal, tetragonal/orthorhombic, and orthorhombic/rhombohedral transitions, respectively, in agreement with other well established disordered perovskite structures [26][27][28] and with previous studies into different compositions of KLTN [17,25]. We note that dielectric dispersion is detected along the entire range of the four observed structural phases, here indicated as P cub , P tet , P ort , P rho for decreasing temperatures.…”

“…Equation (2) shows how the application of an electric field increases the entropy if ∂ s /∂T is positive, while it decreases entropy when it is negative. As pointed out by Fröhlich, in disordered dipolar systems (which we call "dipolar liquidlike" in analogy with [17,41]) an applied electric field creates order since it orients the dipoles otherwise randomly arranged; as a consequence the s entropy variation induced by the field ("Fröhlich entropy") is negative. On the contrary, in dipolar ordered systems (which, similarly to the previous term, we call "dipolar solidlike"), the field perturbs the established ordered state and the fieldinduced entropy s is positive (see Fig.…”

“…These are correlated mesoscopic regions of polarizations that are widely considered responsible for the giant electro-optic and piezoelectric effect [5,14,15]. Moreover, these PNRs can behave as liquid, solid, and even glassy systems, in the so-called nonergodic dipolar regimes, and all this in one and the same crystal structure, typically a large scale perovskite [16][17][18]. How exactly a crystal is able to host a dynamic population of dipoles is still an open question, and its understanding evidently lies at the heart of future applications [5,11,12].…”

The effect of B site cations on the electronic structure of para-electric KTa1/2Nb1/2O3 crystal

“…For example, wonderful holographic data storage was found by studying the electrical transport characteristics of KTN, crossover from fluctuation-driven continuous transitions to first-order transitions was obtained under the application of magnetic fields or uniaxial stresses [3]; Hofmeister et al found the photorefractive effect in a strained centrosymmetry KTN crystal under no applied electric field [4]. More recently, relaxation process behaving according to the Vogel-Fulcher-Tammann model in copper-doped KTN was observed by dielectric spectroscopy over a wide frequency and temperature range [5], quadrupole perturbed 93 Nb NMR spectra of a KTN single crystal doped with 15% Nb was also measured [6], a dielectric relaxation process with nonmonotonic temperature dependence, which was interpreted in terms of the free volume model, was observed in ferroelectric KTN:Cu [7]. From above-mentioned, we can find that KTN has been studied experimentally using various techiques.…”

Injected-charge-driven increase in electro-optic effect of KTN crystals

“…In addition, they have recently attracted growing interest because they exhibit a unique optical response as out-of-equilibrium ferroelectrics around Tc. 5,6 When the host glass of the polar nanoregions (PNRs) in KTN crystals is cooled rapidly around Tc, [5][6][7] the PNRs show an anomalously large static susceptibility, which activates the scale-free optics. 7,8 We proposed a KTN EO scanner as an application using the space-charge-controlled mode of electrical conduction.…”