Structural phase transitions and electrical properties of (K Na1−)NbO3-based ceramics modified with Mn

Mgbemere, Henry E.; Hinterstein, Manuel; Schneider, Gerold A.

doi:10.1016/j.jeurceramsoc.2012.07.033

Cited by 50 publications

(43 citation statements)

References 37 publications

(33 reference statements)

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“…As the number of surface coatings was increased to 6, the piezoelectric constant d 33 increased from 122 to 173 pC/N. The piezoelectric constant d 33 of 173 pC/N is comparatively higher than those of existing LNKMN ceramics fabricated by using a conventional powder process by about 11 pC/N [4]. This remarkable increase can be related to the disappearance of the pores and to the densification of the ceramic surface.…”

Section: Experiments and Discussionmentioning

confidence: 88%

“…Recently, (Na x K 1−x )NbO 3 [NKN]based ceramics have especially received attention as leadfree piezoelectric ceramics [2][3][4][5][6][7][8][9][10]. However, because they have serious problems, such as the volatilization of Na 2 O and K 2 O during sintering, which results in unstable phases and bending or cracking of elaborate shapes, and considerable a number of pores, the electrical properties are degraded.…”

Section: Introductionmentioning

confidence: 99%

“…Mn 3+ , and Mn 4+ ) and because of its ability to improve sintering, to reduce the resistivity and to improve the mechanical quality factor of piezoelectric ceramics [4,11]. Mn also promotes densification and slightly lowers the coercive field and the leakage current in NKN-based piezoelectric ceramics [10].…”

Section: Introductionmentioning

confidence: 99%

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Preparation and characterization of Mn-doped Li0.06(Na0.5K0.5)0.94NbO3 lead-free piezoelectric ceramics with surface sol-gel coatings

Yoo

Lee

2014

Journal of the Korean Physical Society

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This study investigated the effects of Mn doping and sol-gel surface coating on the structural and the electrical properties of lead-free Li0.06(K0.5Na0.5)0.94NbO3(LNKN) ceramics in disc form for use as eco-friendly piezoelectric devices. The 1-mol% Mn-doped LNKN ceramic showed a relatively high piezoelectric constant owing to its high density in the case of its being annealed at a temperature of 1010 • C. A Mn-doped LNKN sol-gel solution with the same composition as that of the ceramics was spin-coated and sintered on both sides of the ceramic surfaces to acquire improved electrical properties. The sol-gel surface coating could play a decisive role in filling the pores, resulting in flat and stable interfaces between the electrodes and the piezoelectric elements. As a result, the highest piezoelectric constant, d33, of 173 pC/N could be obtained for the Mn-doped LNKN ceramics with 420-nm-thick sol-gel surface coatings.

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Section: Experiments and Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Preparation and characterization of Mn-doped Li0.06(Na0.5K0.5)0.94NbO3 lead-free piezoelectric ceramics with surface sol-gel coatings

Yoo

Lee

2014

Journal of the Korean Physical Society

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“…For x = 0.5, both orthorhombic and cubic structures are tested. As a result, orthorhombic phase describes better the experimental data, but "a" and "c" cell parameters are found to be very close, strongly suggesting P4bm tetragonal phase, rather than the orthorhombic one [45].…”

Section: Introductionmentioning

confidence: 80%

Composite microstructures and piezoelectric properties in tantalum substituted lead-free K0.5Na0.5Nb1-xTaxO3 ceramics

Jean

Schoenstein

Zaghrioui

et al. 2018

Ceramics International

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K0.5Na0.5Nb1-xTaxO3 (KNNT) (with x = 0.00, 0.05, 0.10, 0.20, 0.30, 0.50 and 1) ceramics are prepared by ball milling and two calcinations at 830 °C for 5 hours. Subsequent sintering of centimeter size pellets, 1-2 mm thick, is studied using conventional and spark plasma sintering techniques with various conditions. X-Ray diffraction and Raman spectroscopy phase identification reveal orthorhombic to tetragonal phase transitions occurring at about x = 0.50, associated to chemical disorder. Scanning electron microscope observations and associated energy dispersive X-ray spectroscopy analysis reveal some composite aspect of the ceramics. Substitution of niobium by tantalum, corresponding to x increase, decreases significantly the grain size but also the densification of the ceramics sintered by conventional sintering, while, enhancement of the piezoelectric properties is observed for both sintering techniques.Thanks to parameters optimization of the spark plasma sintering process, temperature-time-pressure, significant improvement of the relative density over 96 %, is obtained for all the compositions sintered between 920 and 960 °C, under 50 MPa, for 5 to 10 minutes with heating rates of 100° C/min. High relative permittivity (εr = 1027), piezoelectric charge coefficient (d33 = 160 pC/N) and piezoelectric coupling factor (kp = 46 %) are obtained in spark plasma sintered K0.5Na0.5Nb1-xTaxO3 composite ceramics, for x ranging between 0.10 and 0.30 and for some specific spark plasma sintering conditions. Thus, tantalum single element substitution on niobium site, combined with spark plasma sintering, is revealed to be a powerful combination for the optimization and the reliability of piezoelectric properties in KNN system.

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“…19 Since the difference between the orthorhombic and monoclinic structures is very small, many researchers used the orthorhombic phase for the refinement of the cell parameters of KNN at room temperature from X-ray diffraction (XRD) 20 and neutron data. 21 Therefore, a lack of consensus regarding the structure of KNN exists and clarification is required. In addition, since the crystal symmetry influences the domain configuration, which affects the electro-mechanical properties of KNN and hence practical applications, it is important to have a technique for domain analysis that relates domain configuration with crystal symmetry details.…”

mentioning

confidence: 99%

Precise determination of phonon constants in lead-free monoclinic (K0.5Na0.5)NbO3 single crystals

Rafiq

Supancic

Costa

et al. 2014

Applied Physics Letters

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A polarized Raman analysis of ferroelectric (K0.5Na0.5)NbO3 (KNN) single crystals is presented. The Raman modes of KNN single crystals are assigned to the monoclinic symmetry. Angular-dependent intensities of A′, A″, and mixed A′ + A″ phonons have been theoretically calculated and compared with the experimental data, allowing the precise determination of the Raman tensor coefficients for (non-leaking) modes in single-domain monoclinic KNN. This study is the basis for non-destructive assessments of domain distribution by Raman spectroscopy in KNN-based lead-free ferroelectrics.

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Structural phase transitions and electrical properties of (K Na1−)NbO3-based ceramics modified with Mn

Cited by 50 publications

References 37 publications

Preparation and characterization of Mn-doped Li0.06(Na0.5K0.5)0.94NbO3 lead-free piezoelectric ceramics with surface sol-gel coatings

Preparation and characterization of Mn-doped Li0.06(Na0.5K0.5)0.94NbO3 lead-free piezoelectric ceramics with surface sol-gel coatings

Composite microstructures and piezoelectric properties in tantalum substituted lead-free K0.5Na0.5Nb1-xTaxO3 ceramics

Precise determination of phonon constants in lead-free monoclinic (K0.5Na0.5)NbO3 single crystals

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