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Soon-Jong Jeong

Bio: Soon-Jong Jeong is an academic researcher from Korea Electrotechnology Research Institute. The author has contributed to research in topics: Ceramic & Piezoelectricity. The author has an hindex of 14, co-authored 111 publications receiving 958 citations.


Papers
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TL;DR: In this article, a relaxor/ferroelectric composite is proposed for off-resonance actuator applications with large electromechanical strain hysteresis and high electric field required for activating the large strain.
Abstract: Recently developed lead-free incipient piezoceramics are promising candidates for off-resonance actuator applications with their exceptionally large electromechanical strains. Their commercialization currently faces two major challenges: high electric field required for activating the large strains and large strain hysteresis. It is demonstrated that design of a relaxor/ferroelectric composite provides a highly effective way to resolve both challenges. Experimental results in conjunction with numerical simulations provide key parameters for the development of viable incipient piezoceramics.

148 citations

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TL;DR: Li2O-excess 095(Na05K05)NbO3-005LiTaO3 (NKN-5LT) ceramics were developed by a conventional sintering process as mentioned in this paper.
Abstract: As a candidate for lead-free piezoelectric materials, Li2O-excess 095(Na05K05)NbO3–005LiTaO3 (NKN–5LT) ceramics were developed by a conventional sintering process The sintering temperature was lowered by adding Li2O as a sintering aid Abnormal grain growth in NKN–5LT ceramics was observed with varying Li2O content This grain-growth behavior was explained in terms of interface reaction-controlled nucleation and growth In the 1 mol% Li2O excess NKN–5LT samples sintered at 1000°C for 4 h in air, the electromechanical coupling factor and the piezoelectric constant of NKN–5LT ceramics were found to reach the highest values of 037 and 250 pC/N, respectively

79 citations

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TL;DR: In this paper, the authors investigated the electrical properties of NKN-5LT ceramics as a function of Na 2 O concentration, and found that the NKN−5LT samples reached the highest values of 0.43 and 230 pC/N, respectively.
Abstract: As a candidate for lead-free piezoelectric materials, Na 2 O excess 95(Na 0.5 K 0.5 )NbO 3 –5LiTaO 3 (NKN–5LT) ceramics were developed by conventional sintering process. Sintering temperature was lowered by adding Na 2 O as a sintering aid. Abnormal grain growth in NKN–5LT ceramics was observed with varying Na 2 O contents. This grain growth behavior was explained in terms of interface reaction-controlled nucleation and growth. The electrical properties of NKN–5LT ceramics were investigated as a function of Na 2 O concentration. In the 1 mol% Na 2 O excess NKN–5LT samples sintered at 1050 °C for 4 h in air, electromechanical coupling factor and piezoelectric constant of NKN–5LT ceramics were found to reach the highest values of 0.43 and 230 pC/N, respectively.

69 citations

Journal ArticleDOI
TL;DR: In this paper, a polycrystalline thermoelastic ferromagnetic shape memory alloy Ni-9.5at was used for cooling and healing with and without magnetic field.
Abstract: Shape change (strain) was observed for a polycrystalline thermoelastic ferromagnetic shape memory alloy Ni–9.5at.% Mn–27at.% Ga upon cooling and healing with and without magnetic field. The shape change occurred at martensite start temperature, MS, and it was increased with increasing magnetic field. A large strain of 0.82% was observed when a magnetic field of 10 kOe was applied under a compressive stress of 126 MPa at 73 °C, several degrees above austenite finish temperature, Af. This magnetic field effect on changes of MS can be explained by a modified Clausius–Clapeyron relationship.

62 citations

Journal ArticleDOI
TL;DR: In this paper, a 1-3 story structured PZT multi-layered actuator was used to construct piezoelectric energy harvesters with polydimethylsiloxane (PDMS).

49 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, general guidelines for the development of lead-free piezoelectric ceramics are presented, ranging from atom to phase diagram, and the current development stage in lead free piezoceramics is then critically assessed.
Abstract: A large body of work has been reported in the last 5 years on the development of lead-free piezoceramics in the quest to replace lead–zirconate–titanate (PZT) as the main material for electromechanical devices such as actuators, sensors, and transducers. In specific but narrow application ranges the new materials appear adequate, but are not yet suited to replace PZT on a broader basis. In this paper, general guidelines for the development of lead-free piezoelectric ceramics are presented. Suitable chemical elements are selected first on the basis of cost and toxicity as well as ionic polarizability. Different crystal structures with these elements are then considered based on simple concepts, and a variety of phase diagrams are described with attractive morphotropic phase boundaries, yielding good piezoelectric properties. Finally, lessons from density functional theory are reviewed and used to adjust our understanding based on the simpler concepts. Equipped with these guidelines ranging from atom to phase diagram, the current development stage in lead-free piezoceramics is then critically assessed.

2,510 citations

Journal ArticleDOI
TL;DR: In this paper, the intrinsic nature of the dielectric and piezoelectric properties of Pb(Zr,Ti)O3 is compared with the various families of soft and hard PZTs.
Abstract: Investigations in the development of lead-free piezoelectric ceramics have recently claimed comparable properties to the lead-based ferroelectric perovskites, represented by Pb(Zr,Ti)O3, or PZT In this work, the scientific and technical impact of these materials is contrasted with the various families of “soft” and “hard” PZTs On the scientific front, the intrinsic nature of the dielectric and piezoelectric properties are presented in relation to their respective Curie temperatures (T C) and the existence of a morphotropic phase boundary (MPB) Analogous to PZT, enhanced properties are noted for MPB compositions in the (Na,Bi)TiO3-BaTiO3 and ternary system with (K,Bi)TiO3, but offer properties significantly lower The consequences of a ferroelectric to antiferroelectric transition well below T C further limits their usefulness Though comparable with respect to T C, the high levels of piezoelectricity reported in the (K,Na)NbO3 family are the result of enhanced polarizability associated with the orthorhombic-tetragonal polymorphic phase transition being compositionally shifted downward As expected, the properties are strongly temperature dependent, while degradation occurs through the thermal cycling between the two distinct ferroelectric domain states Extrinsic contributions arising from domains and domain wall mobility were determined using high field strain and polarization measurements The concept of “soft” and “hard” lead-free piezoelectrics were discussed in relation to donor and acceptor modified PZTs, respectively Technologically, the lead-free materials are discussed in relation to general applications, including sensors, actuators and ultrasound transducers

1,525 citations

Journal ArticleDOI
TL;DR: In this article, a figure of merit analysis for key devices is presented and used to contrast lead-containing and lead-free piezoceramics for demanding applications with high reliability, displacements and frequency as well as a wide temperature range.
Abstract: After twenty years of partly quiet and ten years of partly enthusiastic research into lead-free piezoceramics there are now clear prospects for transfer into applications in some areas. This mimics prior research into eliminating lead from other technologies that resulted in restricted lead use in batteries and dwindling use in other applications. A figure of merit analysis for key devices is presented and used to contrast lead-containing and lead-free piezoceramics. A number of existing applications emerge, where the usage of lead-free piezoceramics may be envisaged in the near future. A sufficient transition period to ensure reliability, however, is required. The use of lead-free piezoceramics for demanding applications with high reliability, displacements and frequency as well as a wide temperature range appears to remain in the distant future. New devices are outlined, where the figure of merit suggests skipping lead-containing piezoceramics altogether. Suggestions for the next pertinent research requirements are provided.

966 citations

Journal ArticleDOI
TL;DR: In this article, a review of the reported piezoelectric energy harvesting from vibration is presented, where various types of vibration devices, piezoceramics and mathematical modeling of vibrational energy harvesting are reviewed.
Abstract: This paper reviews energy harvesting technology from mechanical vibration. Recent advances on ultralow power portable electronic devices and wireless sensor network require limitless battery life for better performance. People searched for permanent portable power sources for advanced electronic devices. Energy is everywhere around us and the most important part in energy harvesting is energy transducer. Piezoelectric materials have high energy conversion ability from mechanical vibration. A great amount of researches have been conducted to develop simple and efficient energy harvesting devices from vibration by using piezoelectric materials. Representative piezoelectric materials can be categorized into piezoceramics and piezopolymers. This paper reviews key ideas and performances of the reported piezoelectric energy harvesting from vibration. Various types of vibration devices, piezoelectric materials and mathematical modeling of vibrational energy harvestings are reviewed.

901 citations