Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films

Abazari, M.; Choi, Taekjib; Cheong, S. W.; Safari, A.

doi:10.1088/0022-3727/43/2/025405

Cited by 34 publications

(19 citation statements)

References 21 publications

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“…[10][11][12] In spite of relatively high ferroelectric and piezoelectric properties, the films yet suffered from a high leakage current ͑e.g., Ͼ10…”

mentioning

confidence: 99%

“…It should be noted that the current density in our KNLNT thin film is remarkably lower than that in the KNN-LT-LS based films. [10][11][12] It is speculated that the low current density is attributed to the strong ͑110͒ orientation, as the c-axis oriented or columnar-grained microstructure may offer more leakage current paths through the vertically aligned grain boundaries. 16 Since no significant asymmetry in J-E behavior upon reversal of the polarity of applied voltage can be observed, we will hereafter study the situation in which Pt electrode is positively biased.…”

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confidence: 99%

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Ferroelectric, piezoelectric, and leakage current properties of (K0.48Na0.48Li0.04)(Nb0.775Ta0.225)O3 thin films grown by pulsed laser deposition

Wang

Lin

Kwok

et al. 2011

Applied Physics Letters

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Lead-free ͑K 0.48 Na 0.48 Li 0.04 ͒͑Nb 0.775 Ta 0.225 ͒O 3 ͑KNLNT͒ thin films were deposited on Pt͑111͒ / Ti/ SiO 2 / Si͑001͒ substrates using pulsed laser deposition. The film exhibited a well-defined ferroelectric hysteresis loop with a remnant polarization 2P r of 22.6 C / cm 2 and a coercive field E c of 10.3 kV/mm. The effective piezoelectric coefficient d 33,f of the KNLNT thin films was found to be about 49 pm/V by piezoelectric force microscope. The dominant conduction mechanisms of Au/KNLNT/Pt thin film capacitor were determined to be bulk-limited space-charge-limited-current and Poole-Frenkle emission at low and high electric field strengths, respectively, within a measured temperature range of 130-370 K. © 2011 American Institute of Physics. ͓doi:10.1063/1.3535608͔Because of the increasingly environmental concerns and legislations against the use of lead-based piezoelectric materials in the immediate future, great efforts have been made to develop high performance lead-free piezoelectric materials. 1Among them, ͑K 1−x Na x ͒NbO 3 ͑KNN hereafter͒ is considered to be a promising candidate owing to its pronounced ferroelectric and piezoelectric properties, high Curie temperature, and biocompatible nature. KNN thin films have been grown on various substrates by both physical and chemical approaches.2-8 Pioneer works on thin film KNN materials were mainly focused on undoped compositions in the vicinity of morphotropic phase boundary ͑MPB͒. Good ferroelectricity and high resistivity at low electric field were reported.8 Recent breakthrough in the textured highly piezoelectric Li, Ta, Sb doped KNN ͑KNN-LT-LS͒ ceramics by Saito et al. 9 has triggered intensive studies on KNN-LT-LS based thin films. [10][11][12] In spite of relatively high ferroelectric and piezoelectric properties, the films yet suffered from a high leakage current ͑e.g., Ͼ10−1 A / cm 2 @10 kV/ mm͒ and details of conduction mechanisms remain unclear. Indeed, the participation of toxic Sb in KNN-LT-LS system does not meet the ecological strategy of development of lead-free piezoelectrics.Ours and Hollenstein's studies 13,14 have revealed that Li + and Ta 5+ dual dopants can dramatically enhance the piezoelectric properties of KNN ceramics. The specific composition ͑K 0.48 Na 0.48 Li 0.04 ͒͑Nb 0.775 Ta 0.225 ͒O 3 ͑KNLNT hereafter͒ possesses optimal piezoelectric properties at room temperature due to the coexistence of tetragonal and orthorhombic phases. This MPB-like behavior and less processing and compositional complexity, especially the absence of toxic Sb content, as compared with KNN-LT-LS, have made KNLNT a promising candidate for biocompatible piezoelectric device applications. In this letter, we reported the excellent ferroelectric and piezoelectric properties, and low leakage current density in KNLNT thin films grown by pulsed laser deposition ͑PLD͒. Conduction mechanisms of the KNLNT thin films were investigated in detail.The stoichiometric target of KNLNT used for laser ablation was fabricated by the conventional solid state reaction...

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“…[10][11][12] In spite of relatively high ferroelectric and piezoelectric properties, the films yet suffered from a high leakage current ͑e.g., Ͼ10…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Ferroelectric, piezoelectric, and leakage current properties of (K0.48Na0.48Li0.04)(Nb0.775Ta0.225)O3 thin films grown by pulsed laser deposition

Wang

Lin

Kwok

et al. 2011

Applied Physics Letters

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“…5.13b. The hardening effect of Mn has been also confirmed by the measurement of the piezoelectric coefficient (d 33 ) of base and Mn-doped films which shows that Mn-addition is accompanied by a decline in the d 33 value from 53 pm V À1 in an undoped film to 45 pm V À1 in an Mn-doped film [107]. Yamazoe et al [109] reported that the introduction of a NN buffer layer (150 nm thick) on Pt/(001)MgO substrates had a noticeable effect on the improvement of the ferroelectric properties of KNN-LT-LS films.…”

Section: à2mentioning

confidence: 71%

“…Abazari et al studied the effect of the substrate temperature and oxygen background pressure as well as different dopants (Mn, Ba, and Ti) on the ferroelectric properties of KNN-LT-LS thin films deposited on SrRuO 3 (SRO) coated SrTiO 3 (STO) substrates [103][104][105][106][107]. Figure 5.10 depicts the evolution of the microstructure of the KNN-LT-LS thin films at different deposition temperatures.…”

Section: Knn Films Prepared By Physical Deposition Techniquesmentioning

confidence: 99%

Lead-Free KNN-Based Piezoelectric Materials

Safari

Hejazi

2011

Lead-Free Piezoelectrics

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Sodium potassium niobate with the general chemical formula of K 1 À x Na x NbO 3 (KNN hereafter) is one of the most attractive lead-free materials which have been extensively investigated throughout the last decade.KNN is a solid solution of NaNbO 3 (NN) and KNbO 3 (KN) compounds. A KNN phase diagram comprised of the tetragonal, orthorhombic, and monoclinic ferroelectric regions and an orthorhombic antiferroelectric region is depicted in Fig. 5.1.The phase transitions and variations of dielectric properties of pure KNN vs. temperature resemble those of BaTiO 3 (BT), but every transition occurs at a higher temperature compared to BT ceramics.

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“…Values of ferroelectric polarization and piezoelectric coefficient are far inferior as compared to bulk KNN. Abazari et al studied the domain structure of epitaxial KNN-LT-LS lead-free piezoelectric thin films deposited on SrTiO 3 substrate and measured the effective longitudinal piezoelectric coefficient d 33 using PFM [109]. They found that films possessed tetragonal crystal structure with predominantly c-axis oriented domains and d 33 value was about 45 pmV À1 for 500 nm Mn-doped films.…”

Section: Chemical Depositionmentioning

confidence: 99%