Controllable Gradient in the Composition of a Ferroelectric Single Crystal

Abstract

Graded ferroelectric materials have attracted great attention because of their peculiar properties arising from the evolution of their microscopic structure. Graded bulk materials are advantageous because of their unique effects that can only be observed in bulk samples. A tetragonal KTa 1−x Nb x O 3 single crystal with graded composition (GC) was designed and grown with the goal of exploring the effects of GC on the macroscopic properties of the crystal. The crystal was produced via the top-seed solution growth method. A mechanism of the formation of an internal electric field induced by GC was elucidated, and an enhancement of the strain was observed as a result of the internal electric field.

Ultra-high piezoelectric properties and labyrinthine-domain structure in (K,Na)(Ta,Nb)O3 with phase boundaries

“…Based on these coercive fields, there should be an internal bias electric field in the samples that might originate from the local composition gradient for Ta/Nb and K/Na. 30 However, for the KNTN28 sample, the internal bias field was much lower than the coercive field, which generated symmetric butterfly loops. In addition, the sensitivity of the amplitude to the voltage of KNTN41 is more than twice as high as that of KNTN28, which implies that the macroscopic piezoelectric coefficient is affected by the local piezoelectric response.…”

“…1(b). 29,30 Thereafter, we cut slices from the top, middle, and bottom parts of the KNTN crystal along the (001) PC plane.…”

Electrocaloric effect enhancement in compositionally graded ferroelectric thin films driven by a needle-to-vortex domain structure transition

“…With the advent of modern thin-film deposition approaches, compositionally graded ferroelectric (CGFE) thin films have been produced [34][35][36], in which the material composition can vary spatially throughout the thickness of the film. In addition, the composition gradient can also be accurately controlled in CGFE films [37,38]. The variation in material composition adds a broken spatial inversion symmetry into CGFE films over long distances and brings about incompatible interactions among electrical polarization degrees of freedom [39].…”