Evolution of textured microstructure of Li-doped (K,Na)NbO3 ceramics prepared by reactive templated grain growth

Zhang, Zhiqiang; Yang, Jie; Liu, Zhifu; Li, Yongxiang

doi:10.1016/j.jallcom.2014.11.071

Cited by 26 publications

(4 citation statements)

References 24 publications

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“…), the formation of solid solutions, K/Na ratio, and others. In addition, other methods besides the construction of phase boundaries also affect the piezoelectricity of KNN-based materials, such as sintering temperatures, ,− reactive template grain growth, ,,− spark-plasma sintering, ,− nonstoichiometry, ,,,− two-step sintering, ,− single crystal, ,− ,− poling conditions, ,,,− sintering ai...…”

Section: Type and Construction Of Phase Boundariesmentioning

confidence: 99%

Potassium–Sodium Niobate Lead-Free Piezoelectric Materials: Past, Present, and Future of Phase Boundaries

2015

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compositions but also the temperatures, as shown in Figure 5a. Such a phase boundary is obviously different from that of PZT (see Figure 5b). Regardless of the presence of MPB or PPT characteristics, the polarization of a piezomaterial can be more easily rotated among different symmetries when the compositions are located at the phase boundaries, inducing an enhancement in dielectric and piezoelectric properties. However, recent advances indicate that there is a limited improvement in the d 33 values for KNN materials with O−T or R−O phase boundaries, 90−105,250−252 which is also inferior to most PZT ceramics 5 or even textured KNN. 12 As a result, the formation of R−T boundaries that are similar to PZT may become necessary to further enhance the piezoelectric activity of KNN, because the easy rotations of polarization axes can be induced in compositions near such a phase boundary. 11,35,70,76,106−117 In addition, we recently confirmed this assumption in potassium−sodium niobate piezoceramics by experimental methods, 106−116 and a larger d 33 value has been attained by constructing R−T phase boundaries. 106−112

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Section: Type and Construction Of Phase Boundariesmentioning

confidence: 99%

Potassium–Sodium Niobate Lead-Free Piezoelectric Materials: Past, Present, and Future of Phase Boundaries

2015

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“…The formation of a liquid phase in a RTGG process has been postulated by several reports though no direct evidence was presented. 15,17,18 The composition of the liquid phase has more Na than K and a higher amount of Ta compared with the matrix phase (Fig. S3 †).…”

Section: Resultsmentioning

confidence: 99%

Mechanistic interpretation of the reactive templated grain growth process of (Li, Ta, Sb) modified (K, Na)NbO₃textured lead-free piezoceramics

Zhang

Lü

et al. 2016

CrystEngComm

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Reactive templated grain growth (RTGG) is a promising synthetic method for textured ceramics especially for high performance lead-free piezoceramics. However, the sintering mechanism in a RTGG process remains unclear. In this study, we perform detailed structural and compositional characterization of KNNbased piezoceramics sintered at four elevated temperatures, i.e. 800 °C, 1100 °C, 1140 °C and 1190 °C, in order to precisely examine the phase and microstructure evolution during the RTGG processes. Upon increasing the temperature up to 1190 °C, the sintering system undergoes successive processes, including elemental interdiffusion between the matrix grains and NN templates, formation of a eutectic compound and hence melting of matrix grains, nucleation and epitaxial growth on template surfaces, and finally coarsening of epitaxial crystals by consuming the intermediate liquid phase. Finally, suggestions for rational design and fabrication of textured lead-free piezoceramics using RTGG are proposed.

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“…The resultant samples would obtain the anisotropic structures with improved physical and mechanical properties [9,22]. During the process, the required characteristics of the templates are crucial, such as uniform structure, complete crystal morphology, and stable chemical properties [23][24][25][26][27]. Furthermore, the plate-like KNN particles are expected to inherit the morphology and structure of the precursor [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of two-dimensional lead-free (K, Na)NbO3 micro/nano piezoelectric structures

et al. 2020

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Two-dimensional (2D) lead-free (K, Na)NbO 3 (KNN) micro/nano structures with controllable K/Na ratio were successfully fabricated via a two-step molten salt synthesis (MSS). In this work, the reaction factors, including the proportion of molten salts, the types of carbonates, the sintering temperature, and the sintering time, were discussed in detail and the optimized condition was identified. The microstructure of KNN was confirmed by confocal Raman spectroscopy, while piezoresponse force microscopy (PFM) was applied to measure three-dimensional (3D) morphology and piezoelectric properties of KNN particles. The as-synthesized KNN platelets apparently possess anisotropic morphology and uniform structure, the size of which reaches 5-20 µm in length/width and 0.5-1 µm in thickness. It should be noted that the K/Na ratios of the KNN crystals are basically consistent while the proportion of salts changes within a certain range. The enrichment of Na element in the products is also observed, which owes to the smaller ionic radius of Na + comparing to that of K +. This result provides a reference for the further preparation of textured ceramics and flexible piezoelectric generators.

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Evolution of textured microstructure of Li-doped (K,Na)NbO3 ceramics prepared by reactive templated grain growth

Cited by 26 publications

References 24 publications

Potassium–Sodium Niobate Lead-Free Piezoelectric Materials: Past, Present, and Future of Phase Boundaries

Potassium–Sodium Niobate Lead-Free Piezoelectric Materials: Past, Present, and Future of Phase Boundaries

Mechanistic interpretation of the reactive templated grain growth process of (Li, Ta, Sb) modified (K, Na)NbO₃textured lead-free piezoceramics

Synthesis and characterization of two-dimensional lead-free (K, Na)NbO3 micro/nano piezoelectric structures

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Evolution of textured microstructure of Li-doped (K,Na)NbO3 ceramics prepared by reactive templated grain growth

Cited by 26 publications

References 24 publications

Potassium–Sodium Niobate Lead-Free Piezoelectric Materials: Past, Present, and Future of Phase Boundaries

Potassium–Sodium Niobate Lead-Free Piezoelectric Materials: Past, Present, and Future of Phase Boundaries

Mechanistic interpretation of the reactive templated grain growth process of (Li, Ta, Sb) modified (K, Na)NbO3textured lead-free piezoceramics

Synthesis and characterization of two-dimensional lead-free (K, Na)NbO3 micro/nano piezoelectric structures

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Product

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Mechanistic interpretation of the reactive templated grain growth process of (Li, Ta, Sb) modified (K, Na)NbO₃textured lead-free piezoceramics