Enhanced off-resonance magnetoelectric response in laser annealed PZT thick film grown on magnetostrictive amorphous metal substrate

A highly dense, 4 mu m-thick Pb(Zr, Ti)O-3 (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 longer-wavelength 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 film-composites 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. (C) 2015 AIP Publishing LLC.11Nsciescopu

Growth of self-textured barium hexaferrite ceramics by normal sintering process and their anisotropic magnetic properties

In this report a simple and low-cost technique for growing highly textured barium hexaferrite ceramics without the need for flux or seed crystals to achieve grain orientation is demonstrated. Plate-like shaped barium hexaferrite particles were synthesized using a solid-state reaction process and then aligned under a weak magnetic field, followed by uniaxial compaction. The aligned hexaferrite particles appear to serve as seeds, forming textured grains during sintering. The development of texture was verified by X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and vibration sample magnetometer (VSM) measurements. The prepared high-quality hexaferrite ceramics exhibited good anisotropic magnetic properties, comparable to those of single crystal counterparts. A mechanism for the formation of the self-textured grain growth of the barium hexaferrite ceramics, which involves grain boundary and lattice diffusion and interface reaction processes, is proposed. (C) 2017 Elsevier Ltd. All rights reserved.113Nsciescopu

Energy storage performance of ferroelectric ZrO2 film capacitors: effect of HfO2:Al2O3 dielectric insert layer

The present work reports for the first time, the employment of ferroelectric ZrO2 films as energy storage capacitors utilized in pulsed power systems. Furthermore, the effect of insertion of a low permittivity dielectric HfO2:Al2O3 (HAO) layer, with a thickness ranging from 2 to 8 nm, on the tunability of ferroelectric and energy storage characteristics of ZrO2 films is assessed. The increase in thickness of the HAO layer gave rise to distorted ferroelectric loops with decreased polarization, coercive field, and hysteresis loss of the films. These results are correlated with the depolarization field induced by the insertion of the dielectric HAO layer. An optimum combination of high energy density of 54.3 J cm−3 and good storage efficiency of 51.3% are obtained for the ZrO2 film capacitors with 2 nm-thick HAO insert layer. These values correspond to an increase of ∼55% and ∼92%, from the respective values of pure ZrO2 film capacitors. In addition, the HAO/ZrO2 films showed a good fatigue endurance of energy storage performance over 109 electric field cycles. The energy storage density obtained from HAO(2 nm)/ZrO2 film capacitor is found to be higher than that reported for several Pb-based as well as Pb-free ferroelectric ceramic films with complex compositions. The present study demonstrates that simple binary oxides such as ZrO2 with ferroelectric behavior could be potential candidates for developing high performance energy storage capacitors.This work was supported by: (i) the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding Contracts UIDB/04650/2020 and the Scientific and Technological Cooperation Program between Portugal (FCT) and Morocco (CNRST) – 2019/2020; (ii) DST-SERB, Govt. of India through Grant No. ECR/2017/00006. C. I., R. N. and C. G. acknowledge the financial support from the Romanian Ministry of Education and Research within the project PN3– PCCF PN-III-P4-ID-PCCF2016-0047, contract no. 16/2018. The authors acknowledge the CERIC-ERIC Consortium for access to experimental facilities and financial support under proposal 20192055