Dynamic Behavior of Polar Nanoregions in Re‐Entrant Relaxor 0.6Bi(Mg_1/2Ti_1/2)O₃–0.4PbTiO₃

Abstract

The existence of polar nanoregions (PNRs) is the most important characteristic of ferroelectric relaxors; however, the size determination and the dynamic of PNRs remain uncertain. Herein, it is revealed that a re‐entrant relaxor behavior and ferroelectric–paraelectric transition coexist in complex perovskite oxide 0.6Bi(Mg1/2Ti1/2)O3‐0.4PbTiO3. Two dielectric anomalies, 1) the low‐temperature re‐entrant relaxor transition and 2) the high‐temperature diffuse phase transition (DPT), are described by the phenomenological statistical model. The sizes of the two kinds of PNRs corresponding to two ferroelectric states were obtained. The dynamics of PNRs are analyzed using isothermal electrical modulus, which shows three critical temperatures associated with the DPT, the formation, and freezing of PNRs, respectively. The temperature evolution of the PNRs evolution depends on the stoichiometry of bismuth. The results provide new insights into the dynamic behavior of PNRs and the modification way of re‐entrant relaxor behavior.

Origin of high‐temperature piezoelectric stability and polar nanoregions dynamics in 0.55Bi(Mg1/2Ti1/2)O3–0.45PbTiO3

“…Notably, the (2 0 0) reflection peak exhibits complete splitting into (0 0 2) and (2 0 0) peaks, indicating the formation of a tetragonal symmetry. To investigate the crystal symmetry of the 0.55BMT–0.45PT, we performed Rietveld refinement on all patterns, employing the mixture phase model P 4 mm + Pm $$\overline 3 $$ m 24 . An interesting observation is that the A‐site cations occupy the space between the octahedra, whereas the B‐site cations are positioned at the center of the octahedra, forming an ideal cubic structure with a space group of Pm $$\overline 3 $$ m .…”

“…As highlighted in our early publications, the 0.65Bi(Mg 1/2 Ti 1/2 )O 3 -0.35PbTiO 3 system exhibits reentrance dipole glass-like behavior, suggesting that the lowtemperature relaxor behavior arise from the formation, growth, and freezing of polar nanoregions (PNRs). [23][24][25] To explore the development of (1 − x)BMT-xPT with high-temperature piezoelectric properties, it is essential to investigate and properly understand the underlying mechanisms involving the evolution of PNRs and domain switching that contribute to the relationship between the material's structure and its piezoelectric characteristics. In this study, we focused on understanding the origins of ferroelectric polarization and the reentrant relaxor behavior observed in the (1 − x)BMT-xPT (x = 0.45) system.…”

Ultrahigh Energy Storage in Tungsten Bronze Dielectric Ceramics Through a Weakly Coupled Relaxor Design

“…This enhanced activation energy suggests that the polar clusters (or polar nanoregions, PNRs) within the system are discrete and frustrated, resulting in a weaker coupling between the neighboring clusters. [57] Furthermore, under field-cooled conditions, the formation of long-range dipole arrangements becomes challenging, [58,59] but the application of high fields can still induce the dipole switching, even at low temperatures. This is beneficial for energy storage, as it is associated with a higher polarization saturation field and a slimmer P-E loop (or lower energy loss).…”

Origin of the ultra-wide temperature dielectric stability and dynamic behavior of nanoregions in 0.6Bi(Mg0.5Ti0.5)O3–0.4Ba0.8Ca0.2(Ti0.875Zr0.125)O3

“…49,50 In low and mid-temperature regions [(100–600 K) and (600–820 K)], the system shows a re-entrant relaxor behavior and a DPT, respectively, which originates from the complex ionic substitution at A and/or B sites that gives rise to NMS, as happened in the systems of Bi(Mg 1/2 Ti 1/2 )O 3 –PbTiO 3 , BiScO 3 –BaTiO 3 and Bi(Zn 1/2 Ti 1/2 )O 3 –BaTiO 3 . 51,52 where ω 1 ( T ) represents the proportional distribution of analogy Maxwell–Boltzmann, which describes the ability of dipoles (which can overcome the potential well) to align with each other under thermal fluctuation (similar to Fermi–Dirac function). Two critical temperatures corresponding to the formations of PNRs and NMS give rise to the largest change rate of ω 1 ( T ).…”