Rayleigh analysis of dielectric properties in textured K0.5Na0.5NbO3 ceramics

Haugen, Astri Bjørnetun; Morozov, Maxim I.; Jones, Jacob L.; Einarsrud, Mari‐Ann

doi:10.1063/1.4902858

Cited by 27 publications

(14 citation statements)

References 35 publications

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“…The dielectric constant at constant strain ( figure 9(a)) is around 200-400 for non-textured samples, and decreases to 250 in the textured samples. This is in agreement with both their higher porosity and previous studies on textured KNN-based samples [43]. The elastic constant C 33 D (figure 9(b)), deduced from the longitudinal wave velocity and density, is decreasing with texture, probably related to their higher porosity compared to the non-textured samples.…”

Section: Fabrication Of Slurries Tapes and Multilayerssupporting

confidence: 91%

Textured multilayered piezoelectric structures for energy conversion

2019

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Piezoelectric materials are essential for the conversion between mechanical and electrical energy, for example in ultrasound imaging and vibrational energy harvesting. Here, we are making and exploring the effects of a new design: co-sintered multilayers with texture (grains of a preferential crystallographic direction). The motivation is the combination of increased piezoelectric response in certain crystallographic directions; multilayer structures where thick films rather than bulk materials can allow higher frequency operation and large area; and co-sintering to avoid detrimental effects from gluing layers together. Samples of the lead-free piezoelectric material Li 0.06 (K 0.52 Na 0.48 ) 0.94 Nb 0.71 Ta 0.29 O 3 with 0.25 mol% Mn (KNNLTM) were made by tape casting and co-sintering. NaNbO 3 platelets with (100) orientation which were used as templates to introduce texture, and polymethyl methacrylate (PMMA) was used as a pore forming agent for making porous substrates. The electrical impedances of the co-sintered samples were recorded and analyzed by equivalent electrical circuit modelling. A texture up to 85% in the [100] crystallographic direction was obtained. The samples displayed ferro-and piezoelectricity, with a maximum thickness coupling coefficient (k t =0.18) between mechanical and electrical energy in the most textured sample. This demonstrates that the introduction of texture in multilayered, co-sintered piezoelectrics shows promise for improving devices for ultrasound imaging or energy harvesting.

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Section: Fabrication Of Slurries Tapes and Multilayerssupporting

confidence: 91%

Textured multilayered piezoelectric structures for energy conversion

2019

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“…This record-high k 33 is very promising for applications in ultrasound transducers [8]. Yet, since single crystals are expensive and limited in size, it is interesting to study this specific KNN-based composition also as a ceramic, and eventually a textured [2,[9][10][11][12] material.…”

Section: Introductionmentioning

confidence: 99%

Hybrid Atmosphere Processing of Lead-Free Piezoelectric Sodium Potassium Niobate-Based Ceramics

Haugen

2019

Ceramics

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K 0.5 Na 0.5 NbO 3 -based ceramics, a promising group of lead-free piezoelectrics, are challenging to sinter dense while avoiding alkali evaporation. This work explores hybrid atmosphere processing, a new approach where reducing atmospheres is used during heating to avoid coarsening from alkali carbonates and hydroxides, and oxidizing atmospheres is used during sintering to avoid alkali evaporation. Discs of Li 0.06 (K 0.52 Na 0.48 ) 0.94 Nb 0.71 Ta 0.29 O 3 with 0.25 mol% Mn (KNNLTM) were sintered in air, N 2 , 9% H 2 in N 2 , or 9% H 2 in N 2 during heating and air during sintering (hybrid atmosphere processing). The highest density was obtained by sintering in 9% H 2 in N 2 , but resulted in high alkali loss and decomposition of the surface, followed by low piezoelectric response. However, with the hybrid H 2 /air processing it was possible to both avoid surface decomposition and leakage currently associated with alkali evaporation during sintering in H 2 , and to obtain a denser, more phase-pure and small-grained KNNLTM ceramic with a higher piezoelectric response than obtained by sintering in air or N 2 .

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“…The Rayleigh law has previously been used to describe the subcoercive piezoelectric and dielectric response of ferroelectrics and can be expressed by the following equations:

P false(E false) = ({normalε}_{r}^{'} (0) + α E_{0}) E \pm \frac{1}{2} α false(E_{0}^{2} - E^{2} false),

{normalε}_{r}^{'} = {normalε}_{r}^{'} (0) + α E_{0},

where ε r ′ is the real part of the relative dielectric permittivity, α is the Rayleigh coefficient, and E 0 is the electric field amplitude , . The Rayleigh region, defined by the range of field amplitudes where the relationship between the ε r ′ and E is linear, is located below the coercive field, where the domain wall density and domain configuration are assumed to be unchanged during the measurement .…”

Section: Discussionmentioning

confidence: 99%

“…It can be used as a measure of the irreversibility of domain wall movement. On the other hand, the term ε r ′(0) refers to the permittivity at zero electric field and contains the intrinsic ionic response and the reversible domain wall vibration …”

Section: Discussionmentioning

confidence: 99%

Influence of composition on the unipolar electric fatigue of Ba(Zr_0.2Ti_0.8)O₃‐(Ba_0.7Ca_0.3)TiO₃ lead‐free piezoceramics

et al. 2017

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The lead-free (1Àx)Ba(Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 system is considered as promising candidate for the replacement of lead-based piezoceramics in actuation applications, during which electric fatigue is a major concern. This issue was addressed in this work, where the unipolar fatigue resistance of three (1Àx)Ba (Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 compositions with different crystallographic structures (rhombohedral, orthorhombic, and tetragonal) was evaluated. Strain asymmetry and development of an internal bias field were observed in all compositions. The decrease in the remanent polarization and the large signal piezoelectric coefficient after 10 7 unipolar cycles was found to lie between 6%-12% and 2%-13%, respectively. The most pronounced fatigue was observed for the orthorhombic composition, which has the largest extrinsic contribution to strain. On the other hand, the best fatigue resistance was observed for the tetragonal composition, which has a predominantly intrinsic strain response. The correlation of fatigue resistance with strain mechanism was corroborated with determination of the Rayleigh parameters and changes in the domain morphology after cycling as confirmed by piezoresponse force microscopy. K E Y W O R D Scyclic fatigue, domains, fatigue, lead-free ceramics, piezoelectric materials/properties

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Rayleigh analysis of dielectric properties in textured K0.5Na0.5NbO3 ceramics

Cited by 27 publications

References 35 publications

Textured multilayered piezoelectric structures for energy conversion

Textured multilayered piezoelectric structures for energy conversion

Hybrid Atmosphere Processing of Lead-Free Piezoelectric Sodium Potassium Niobate-Based Ceramics

Influence of composition on the unipolar electric fatigue of Ba(Zr_0.2Ti_0.8)O₃‐(Ba_0.7Ca_0.3)TiO₃ lead‐free piezoceramics

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Rayleigh analysis of dielectric properties in textured K0.5Na0.5NbO3 ceramics

Cited by 27 publications

References 35 publications

Textured multilayered piezoelectric structures for energy conversion

Textured multilayered piezoelectric structures for energy conversion

Hybrid Atmosphere Processing of Lead-Free Piezoelectric Sodium Potassium Niobate-Based Ceramics

Influence of composition on the unipolar electric fatigue of Ba(Zr0.2Ti0.8)O3‐(Ba0.7Ca0.3)TiO3 lead‐free piezoceramics

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Influence of composition on the unipolar electric fatigue of Ba(Zr_0.2Ti_0.8)O₃‐(Ba_0.7Ca_0.3)TiO₃ lead‐free piezoceramics