High-power impedance spectroscopy for lead-free alkali niobate piezoceramics

Self Cite

In this study, stress-dependent impedance spectra were characterized as a function of uniaxial compressive stress up to –300 MPa for Zr-doped (Na0.55K0.45)(Nb1-x/125Zrx/100)O3-δ (x =5, 10 mol%). This allowed for the evaluation of the stress-induced changes in the grain and grain boundary capacitance. The grain capacitance from equivalent circuit fitting exhibited decreasing behavior with increasing uniaxial compressive stress increased, which is attributed to hindered domain wall movement reducing the extrinsic contributions. Interestingly, NKNZ10 showed a more significant degradation in grain capacitance than NKNZ5. One possible explanation is the difference in oxygen vacancies, and by extension defect dipoles, when introducing Zr into the lattice. As such, this study reveals the amplifying effect of oxygen vacancies on the mechanical suppression of domain wall movement.

Section: Introductionmentioning

confidence: 99%

Stress dependent impedance spectroscopy of niobium based ceramics

Tanaka,

Nozaki,

Martin

et al. 2023

Self Cite

“…NaNbO 3 (NN)-based ceramics have been studied fervently because of the comparatively outstanding piezoelectric properties and high Curie temperature (T C ). [25][26][27][28] Nevertheless, only few attempt has been focused on energy storage applications of NN-based materials. Although NN is regarded as an AFE nonpolar structure, the characteristic double P-E loops are only observed in high quality NN single crystals during several initial cycles when an external electric field perpendicular to the orthorhombic c axis is applied, while square shaped P-E loops are manifested of polycrystalline NN ceramics at RT.…”

Section: Introductionmentioning

confidence: 99%

Effect of La(Nb_1/3Mg_2/3)O₃ addition on phase transition behavior and energy storage properties of NaNbO₃ ceramics

Zhang

Karaki

Fujii

2021

The doped NaNbO 3 ceramics of (1−x)NaNbO 3 -xLa(Nb 1/3 Mg 2/3 )O 3 were prepared by conventional solid state method, and then the dielectric, phase transition and energy storage performances were investigated. The X-ray diffraction results showed a phase transition from orthorhombic to rhombohedral occurred with the increase of x. The introduction of additives induced the first-order anti-ferroelectric phase transition and decrease of phase transition temperatures. As a result, an enhanced recoverable energy storage density of 1.45 J cm −3 was observed when x = 4.5% with an efficiency of 69.6% under a moderate electric field. The thermal hysteresis phenomenon was attractive not only in chemical modification but also in the enhancement of energy storage properties. This will contribute to the promotion of NaNbO 3 -based dielectric capacitors.

“…It has been reported that the electrical properties of grains and GBs in (Na,K)NbO 3 piezoceramics can be evaluated near the T C , and that domain orientation in a strong electric field is accompanied by spectral changes. 12) The objective of this study is to evaluate the domain structure of multilayered piezoceramics in a fatigued state using the frequency distribution of their impedance spectra. In this study, we analyzed the impedance spectra of Li-modified (Na,K)NbO 3 multilayered piezoceramics near T C to compare the ferroelectric and paraelectric phases.…”

Section: Introductionmentioning

confidence: 99%

Cyclic properties and impedance analysis of (Li,Na,K)NbO₃-based multilayered piezoceramics

Nishiyama

Kakimoto

Hatano

et al. 2020

(Li,Na,K)NbO3-based multilayered piezoceramics were characterized by performing unipolar polarization electric field measurements and impedance spectroscopy. Subjecting an as-poled sample to up to 107 cycles in an applied 4 kV mm−1 unipolar cyclic field at 100 °C reduced its polarization by 8.9%. The impedance spectra of as-sintered, as-poled, and fatigued samples were acquired and analyzed. Two relaxation processes reported to occur in single-layered (Na,K)NbO3-based ceramics were identified. They occurred at inner domains and interfaces, including domain walls (DWs) and grain boundaries, below the Curie temperature (TC, 450 °C). The electrical properties of the samples were evaluated by two resistance-constant phase element (2 R-CPE) equivalent circuit analysis. The results indicated that DW pinning was the primary cause of unipolar fatigue.