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The well‐known ferromagnetic oxide, NiFe2O4, was studied as a potential candidate for room‐temperature Type II magnetoelectrics. A spin canting as one of the essential requirements for Type II multiferroics was induced by breaking the stoichiometry, that is, intentionally subtracting Fe ions. We observed that Fe ions were first subtracted exclusively from the tetrahedral sites, leading to an increase in the magnetoelectric coupling owing to an increasing degree of spin canting. The enhancement in the magnetoelectric coupling culminated beyond the subtraction level of ~30 at.%, at which Fe ions started to be removed from the octahedral sites. Alongside, we observed that the subtraction of Fe ions gives rise to a ferroelectricity due to the formation of defect complexes that establish an internal bias field. [ABSTRACT FROM AUTHOR]

In this study, a flexible magnetoelectric (ME) heterostructure of PZT/Ni was fabricated by depositing a (001) oriented Pb(Zr0.52Ti0.48)O3 (PZT) film on a thin, flexible Ni foil buffered with LaNiO3/HfO2. Excellent ferroelectric properties and large ME voltage coefficient of 3.2 V/cm ⋅ Oe were realized from the PZT/Ni heterostructure. The PZT/Ni composite’s high performance was attributed to strong texturing of the PZT film, coupled with the compressive stress in the piezoelectric film. Besides, reduced substrate clamping in the PZT film due to the film on the foil structure and strong interfacial bonding in the PZT/LaNiO3/HfO2/Ni heterostructure could also have contributed to the high ME performance of PZT/Ni. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric energy harvesters have been regarded as an overarching candidate for achieving self-powered electronic systems for environmental sensors and biomedical devices using the self-sufficient electrical energy. In this research, we realize a flexible high-output and lead-free piezoelectric energy harvester by using the aerosol deposition method and the laser lift-off process. We also investigated the comprehensive biocompatibility of the lead-free piezoceramic device using ex-vivo ionic elusion and in vivo bioimplantation, as well as in vitro cell proliferation and histologic inspection. The fabricated LiNbO3-doped (K,Na)NbO3 (KNN) thin film-based flexible energy harvester exhibited an outstanding piezoresponse, and average output performance of an open-circuit voltage of ~130 V and a short-circuit current of ~1.3 μA under normal bending and release deformation, which is the best record among previously reported flexible lead-free piezoelectric energy harvesters. Although both the KNN and Pb(Zr,Ti)O3 (PZT) devices showed short-term biocompatibility in cellular and histological studies, excessive Pb toxic ions were eluted from the PZT in human serum and tap water. Moreover, the KNN-based flexible energy harvester was implanted into a porcine chest and generated up to ~5 V and 700 nA from the heartbeat motion, comparable to the output of previously reported lead-based flexible energy harvesters. This work can compellingly serve to advance the development of piezoelectric energy harvesting for actual and practical biocompatible self-powered biomedical applications beyond restrictions of lead-based materials in long-term physiological and clinical aspects. [ABSTRACT FROM AUTHOR]

This study reports of an ac magnetic field sensor with pT/√Hz sensitivity based on self-biased magnetoelectric composites made using piezoelectric Pb(Mg 1/3 Nb 2/3 )O 3 -PbZrO 3 -PbTiO 3 (PMN-PZT) single crystals in macro-fiber form and a magnetostrictive Ni plate. Variation in the loss properties of the PMN-PZT single crystals resulted in a substantial change in the magnetic field sensitivity of the ME based sensors. It was found that the loss factor of the piezoelectric layer was one of the key parameters affecting the magnetic field sensitivity. The ME composite sensor structure employing low-loss piezoelectric single crystals achieved a limit of detection (LOD) in the range of a few pT/√Hz at its resonance frequency (500 Hz). This magnitude of sensitivity is much higher than that offered bycommercially available magnetic sensors based on the giant magnetoresistance (GMR) effect or Hall-effect. [ABSTRACT FROM AUTHOR]

An improved magnetic energy harvesting with magneto‐mechano‐electric (MME) generator is demonstrated by low‐loss piezoelectric single‐crystal fibers composite to realize a self‐powered electronics. The low‐loss MME generator can generate voltage of 94 Vpp and current of 120 μA (corresponding to an output root mean square power density of 2.1 mW cm−3). [ABSTRACT FROM AUTHOR]

By tailoring the truncated shape of a cantilever structured magneto-mechano-electric (MME) generator that is composed of a piezoelectric single crystal fiber composite and a magnetostrictive Ni plate, a superior output harvesting power density of over 680% was obtained as compared to a typical rectangular shaped generator. The effect of the MME generator's shape on the strain distribution induced by magnetostriction and vibration characteristics and harvesting properties were simulated by finite element analysis modeling and confirmed experimentally, respectively. The truncated shape was effective for not only utilizing a more uniform in-plane strain distribution in the active piezoelectric area but also magnifying the flexural vibration amplitude, which in turn can make the generator more powerful under tiny magnetic oscillations. [ABSTRACT FROM AUTHOR]

This study demonstrates the modulation of off-resonance magnetoelectric ( ME) response of the Pb(Zr,Ti)O3 ( PZT)/ Metglas (Fe BSi) bilayered composite by laser annealing. A continuous-wave 532 nm Nd: YAG laser with varying fluences (210-390 J/mm2) was utilized to anneal the 2 μm thick PZT film deposited using granule spray in vacuum ( GSV) technique on magnetostrictive amorphous Metglas foil. It was found that the dielectric and ferroelectric properties of the PZT film are strongly affected by the exposure to laser fluence. The ME voltage coefficient of PZT/Metglas increased with the fluence up to 345 J/mm2, reaching a high value of 880 mV/cm·Oe. The electrical and ME properties were correlated with the changes observed in crystallinity and grain size of the PZT film as well as with the alterations in microstructure and magnetic behavior of Metglas. Our results demonstrate that enhanced ME coupling can be realized in PZT/Metglas film composites by controlling the laser fluence. [ABSTRACT FROM AUTHOR]

A highly dense, 4 lm-thick Pb(Zr,Ti)O3 (PZT) film is deposited on amorphous magnetostrictive Metglas foil (FeBSi) by granule spray in vacuum process at room temperature, followed by its localized annealing with a continuous-wave 560 nm ytterbium fiber laser radiation. This longerwavelength laser radiation is able to anneal the whole of thick PZT film layer without any deteriorative effects, such as chemical reaction and/or atomic diffusion, at the interface and crystallization of amorphous Metglas substrate. Greatly enhanced dielectric and ferroelectric properties of the annealed PZT are attributed to its better crystallinity and grain growth induced by laser irradiation. As a result, a colossal off-resonance magnetoelectric (ME) voltage coefficient that is two orders of magnitude larger than previously reported output from PZT/Metglas film-composites is achieved. The present work addresses the problems involved in the fabrication of PZT/Metglas filmcomposites and opens up emerging possibilities in employing piezoelectric materials with low thermal budget substrates (suitable for integrated electronics) and designing laminate composites for ME based devices. [ABSTRACT FROM AUTHOR]

Abstract: Synthesis of nanocrystalline ceria powders is carried out through the mixed fuel combustion approach by using different combinations of glycine and citric acid. The powders obtained with different fuel-to-nitrate (F/N) ratios are characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area analysis, and Raman spectroscopy. TGA and FTIR spectroscopy studies have revealed the presence of carbonaceous species and residual volatiles in the combustion synthesized ceria powders. It is observed that the variation of fuel-to-nitrate ratio has a profound influence on the carbonaceous residues from combustion, crystallite size (11–44nm), surface area (9–39m2/g) and morphology of the resultant powders. The Raman spectroscopy results on the variation of particle size with F/N ratio are consistent with the conclusions made from X-ray line broadening and BET surface area analysis. [Copyright &y& Elsevier]

Dielectric capacitors, which store electrical energy in the form of an electrostatic field via dielectric polarization, are used in pulsed power electronics due to their high power density and ultrashort discharge time. In pursuit of developing high‐performance dielectric capacitors, special attention has been given to the improvement of their energy density and storage efficiency, which would make them useful for an even wider variety of applications. Among the different dielectric materials studied so far, including polymers, glasses, and both bulk and film‐based ceramics, dielectric ceramic films, which are of particular interest for miniature power electronics and mobile platforms, have demonstrated the greatest energy storage performances. In this regard, several interesting approaches involving physical, chemical, and microstructural modifications of the dielectric ceramic films are adopted. In addition to a brief discussion of the polymers, glasses, and ceramics used in dielectric capacitors and key parameters related to their energy storage performance, this review article presents a comprehensive overview of the numerous efforts made toward enhancing the energy storage properties of linear dielectric, paraelectric, ferroelectric, relaxor ferroelectric, and anti‐ferroelectric ceramic films for their applications in pulsed power capacitors. Dielectric capacitors, which store energy in the form of an electrostatic field and release it in an extremely short period of time to create intense power pulses, have applications in pulsed power electronics used in various commercial, civilian, and military systems. Significant progress has been made toward the development of dielectric ceramic film capacitors with high energy storage performance. [ABSTRACT FROM AUTHOR]

Magnetoelectric (ME) film composites consisting of piezoelectric and magnetostrictive materials are promising candidates for application in magnetic field sensors, energy harvesters, and ME antennas. Conventionally, high-temperature annealing is required to crystallize piezoelectric films, restricting the use of heat-sensitive magnetostrictive substrates that enhance ME coupling. Herein, a synergetic approach is demonstrated for fabricating ME film composites that combines aerosol deposition and instantaneous thermal treatment based on intense pulsed light (IPL) radiation to form piezoelectric Pb(Zr,Ti)O 3 (PZT) thick films on an amorphous Metglas substrate. IPL rapidly anneals PZT films within a few milliseconds without damaging the underlying Metglas. To optimize the IPL irradiation conditions, the temperature distribution inside the PZT/Metglas film is determined using transient photothermal computational simulation. The PZT/Metglas films are annealed using different IPL pulse durations to determine the structure-property relationship. IPL treatment results in an enhanced crystallinity of the PZT, thus improving the dielectric, piezoelectric, and ME properties of the composite films. An ultrahigh off-resonance ME coupling (≈20 V cm -1  Oe -1 ) is obtained for the PZT/Metglas film that is IPL annealed at a pulse width of 0.75 ms (an order of magnitude higher than that reported for other ME films), confirming the potential for next-generation, miniaturized, and high-performance ME devices., (© 2023 Wiley-VCH GmbH.)

We report the effect of epoxy adhesion layers with different mechanical or physical property on a magnetoelectric (ME) composite laminate composed of FeBSi alloy (Metglas)/single-crystal Pb(Mg 1/3 Nb 2/3 )O 3 -Pb(Zr,Ti)O 3 /Metglas to achieve an improved ME conversion performance. Through theoretical simulation, it was revealed that the Young's modulus and the thickness of interfacial adhesives were major parameters that influence the conversion efficiency in ME composites. In the experimental evaluation, we utilized three epoxy materials with a distinct Young's modulus and adjusted the average thickness of the adhesion layers to optimize the ME conversion. The experimental results show that a thin epoxy layer with a high Young's modulus provided the best performance in the inorganic-based ME conversion process. By tailoring the interfacial adhesion property, the ME laminate generated a high conversion coefficient of 328.8 V/(cm Oe), with a mechanical quality factor of 132.0 at the resonance mode. Moreover, we demonstrated a highly sensitive alternating current magnetic field sensor that had a detection resolution below 10 pT. The optimization of the epoxy layers in the ME laminate composite provided significant enhancement of the ME response in a simple manner.

Dielectric ceramic film capacitors, which store energy in the form of electric polarization, are promising for miniature pulsed power electronic device applications. For a superior energy storage performance of the capacitors, large recoverable energy density, along with high efficiency, high power density, fast charge/discharge rate, and good thermal/fatigue stability, is desired. Herein, we present highly dense lead-free 0.942[Na 0.535 K 0.480 NbO 3 ]-0.058LiNbO 3 (KNNLN) ferroelectric ceramic thick films (∼5 μm) demonstrating remarkable energy storage performance. The nanocrystalline KNNLN thick film fabricated by aerosol deposition (AD) process and annealed at 600 °C displayed a quasi-relaxor ferroelectric behavior, which is in contrast to the typical ferroelectric nature of the KNNLN ceramic in its bulk form. The AD film exhibited a large recoverable energy density of 23.4 J/cm 3 , with an efficiency of over 70% under the electric field of 1400 kV/cm. Besides, an ultrahigh power density of 38.8 MW/cm 3 together with a fast discharge speed of 0.45 μs, good fatigue endurance (up to 10 6 cycles), and thermal stability in a wide temperature range of 20-160 °C was also observed. Using the AD process, we could make a highly dense microstructure of the film containing nano-sized grains, which gave rise to the quasi-relaxor ferroelectric characteristics and the remarkable energy storage properties.

Enhanced and self-biased magnetoelectric (ME) coupling is demonstrated in a laminate heterostructure comprising 4 μm-thick Pb(Zr,Ti)O 3 (PZT) film deposited on 50 μm-thick flexible nickel (Ni) foil. A unique fabrication approach, combining room temperature deposition of PZT film by granule spray in vacuum (GSV) process and localized thermal treatment of the film by laser radiation, is utilized. This approach addresses the challenges in integrating ceramic films on metal substrates, which is often limited by the interfacial chemical reactions occurring at high processing temperatures. Laser-induced crystallinity improvement in the PZT thick film led to enhanced dielectric, ferroelectric, and magnetoelectric properties of the PZT/Ni composite. A high self-biased ME response on the order of 3.15 V/cm·Oe was obtained from the laser-annealed PZT/Ni film heterostructure. This value corresponds to a ∼2000% increment from the ME response (0.16 V/cm·Oe) measured from the as-deposited PZT/Ni sample. This result is also one of the highest reported values among similar ME composite systems. The tunability of self-biased ME coupling in PZT/Ni composite has been found to be related to the demagnetization field in Ni, strain mismatch between PZT and Ni, and flexural moment of the laminate structure. The phase-field model provides quantitative insight into these factors and illustrates their contributions toward the observed self-biased ME response. The results present a viable pathway toward designing and integrating ME components for a new generation of miniaturized tunable electronic devices.