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Understanding the Role of Ferroelastic Domains on the Pyroelectric and Electrocaloric Effects in Ferroelectric Thin Films
摘要： Temperature- and electric-field-induced structural transitions in a polydomain ferroelectric can have profound effects on its electrothermal susceptibilities. Here, the role of such ferroelastic domains on the pyroelectric and electrocaloric response is experimentally investigated in thin films of the tetragonal ferroelectric PbZr0.2Ti0.8O3. By utilizing epitaxial strain, a rich set of ferroelastic polydomain states spanning a broad thermodynamic phase space are stabilized. Using temperature-dependent scanning-probe microscopy, X-ray diffraction, and high-frequency phase-sensitive pyroelectric measurements, the propensity of domains to reconfigure under a temperature perturbation is quantitatively studied. In turn, the “extrinsic” contributions to pyroelectricity exclusively due to changes between the ferroelastic domain population is elucidated as a function of epitaxial strain. Further, using highly sensitive thin-film resistive thermometry, direct electrocaloric temperature changes are measured on these polydomain thin films for the first time. The results demonstrate that temperature- and electric-field-driven domain interconversion under compressive strain diminish both the pyroelectric and the electrocaloric effects, while both these susceptibilities are enhanced due to the exact-opposite effect from the extrinsic contributions under tensile strain.
关键词： electrocaloric effect,ferroelastic domains,ferroelectricity,pyroelectric effect,entropy
更新于2025-09-10 09:29:36
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Dynamic mechanical and electric behaviors of La-doped BiVO4
摘要： Bismuth vanadate (BiVO4) is an important semiconductor with wide applications, but it is still lack of in-depth understanding for its fundamental dynamic behaviors. To address this issue, the comprehensive analysis of structure, internal friction (IF), modulus, dielectric and impedance spectra was employed to unambiguously disclose the dynamic mechanical and electric behaviors for a series of Bi1-xLaxVO4 ceramics (0 ≤ x ≤ 0.15). In the sensitive mechanical measurement, five IF peaks, corresponding modulus anomalies and high-temperature creep behavior have been observed in our Bi1-xLaxVO4 ceramics. Through analyzing their related kinetic parameters, defect formations and evolution processes, the complex evolution model of ferroelastic domains including four different stages and the origin of grain boundary relaxation are well established. As for the electric experiment, there are two apparently different activation processes in low and high temperature regions, respectively. In conjunction with structural and mechanical characterizations, we confirm that the mixed electric/oxide ionic conduction dominates from 433 to 633 K, undergoing a structural change (633-673 K) to the complicated defect conduction at higher temperatures (673-833 K). Our findings smooth the track for better realization of the fundamental dynamic behaviors as well as extending practical application of BiVO4-based material.
关键词： Bismuth vanadate,dynamic mechanical behaviors,electric behaviors,ferroelastic domains,grain boundary relaxation,electric conduction mechanism,BiVO4,La-doped
更新于2025-09-09 09:28:46