More Like this

1. Giant Energy Density via Mechanically Tailored Relaxor Ferroelectric Behavior of PZT Thick Film

   https://doi.org/10.1002/adma.202302554  

   Peddigari, Mahesh; Wang, Bo; Wang, Rui; Yoon, Woon‐Ha; Jang, Jongmoon; Lee, Hyunjong; Song, Kyung; Hwang, Geon‐Tae; Wang, Kai; Hou, Yuchen; et al (September 2023, Advanced Materials)

   Abstract Relaxor ferroelectrics (RFEs) are being actively investigated for energy‐storage applications due to their large electric‐field‐induced polarization with slim hysteresis and fast energy charging–discharging capability. Here, a novel nanograin engineering approach based upon high kinetic energy deposition is reported, for mechanically inducing the RFE behavior in a normal ferroelectric Pb(Zr_0.52Ti_0.48)O₃(PZT), which results in simultaneous enhancement in the dielectric breakdown strength (E_DBS) and polarization. Mechanically transformed relaxor thick films with 4 µm thickness exhibit an exceptionalE_DBSof 540 MV m⁻¹and reduced hysteresis with large unsaturated polarization (103.6 µC cm⁻²), resulting in a record high energy‐storage density of 124.1 J cm⁻³and a power density of 64.5 MW cm⁻³. This fundamental advancement is correlated with the generalized nanostructure design that comprises nanocrystalline phases embedded within the amorphous matrix. Microstructure‐tailored ferroelectric behavior overcomes the limitations imposed by traditional compositional design methods and provides a feasible pathway for realization of high‐performance energy‐storage materials. 

   more » « less
2. Ultrahigh capacitive energy density in ion-bombarded relaxor ferroelectric films

   https://doi.org/10.1126/science.abb0631  

   Kim, Jieun; Saremi, Sahar; Acharya, Megha; Velarde, Gabriel; Parsonnet, Eric; Donahue, Patrick; Qualls, Alexander; Garcia, David; Martin, Lane W. (July 2020, Science)

   Dielectric capacitors can store and release electric energy at ultrafast rates and are extensively studied for applications in electronics and electric power systems. Among various candidates, thin films based on relaxor ferroelectrics, a special kind of ferroelectric with nanometer-sized domains, have attracted special attention because of their high energy densities and efficiencies. We show that high-energy ion bombardment improves the energy storage performance of relaxor ferroelectric thin films. Intrinsic point defects created by ion bombardment reduce leakage, delay low-field polarization saturation, enhance high-field polarizability, and improve breakdown strength. We demonstrate energy storage densities as high as ~133 joules per cubic centimeter with efficiencies exceeding 75%. Deterministic control of defects by means of postsynthesis processing methods such as ion bombardment can be used to overcome the trade-off between high polarizability and breakdown strength. 

   more » « less
3. The development of 2D materials for electrochemical energy applications: A mechanistic approach

   https://doi.org/10.1063/1.5085187  

   Hynek, David_J; Pondick, Joshua_V; Cha, Judy_J (March 2019, APL Materials)

   Energy production and storage is one of the foremost challenges of the 21st century. Rising energy demands coupled with increasing materials scarcity have motivated the search for new materials for energy technology development. Nanomaterials are an excellent class of materials to drive this innovation due to their emergent properties at the nanoscale. In recent years, two dimensional (2D) layered materials have shown promise in a variety of energy related applications due to van der Waals interlayer bonding, large surface area, and the ability to engineer material properties through heterostructure formation. Despite notable results, their development has largely followed a guess and check approach. To realize the full potential of 2D materials, more efforts must be made towards achieving a mechanistic understanding of the processes that make these 2D systems promising. In this perspective, we bring attention to a series of techniques used to probe fundamental energy related processes in 2D materials, focusing on electrochemical catalysis and energy storage. We highlight studies that have advanced development due to mechanistic insights they uncovered. In doing so, we hope to provide a pathway for advancing our mechanistic understanding of 2D energy materials for further research. 

   more » « less
4. Coexisting Phases in NaNbO ₃ Thin Films Influenced by Epitaxial Strain and Size Effects

   https://doi.org/10.1002/advs.202510099  

   Khandelwal, Aarushi; Crust, Kevin_J; Ghanbari, Reza; Yu, Yijun; Xu, Ruijuan; Hwang, Harold_Y (October 2025, Advanced Science)

   Abstract Antiferroelectrics are a promising class of materials for applications in capacitive energy storage and multi‐state memory, but comprehensive control of their functional properties requires further research. In thin films, epitaxial strain and size effects are important tuning knobs but difficult to probe simultaneously due to low critical thicknesses of common lead‐based antiferroelectrics. Antiferroelectric NaNbO₃enables opportunities for studying size effects under strain, but electrical properties of ultra‐thin films have not been thoroughly investigated due to materials challenges. Here, high‐quality, epitaxial, coherently‐strained NaNbO₃films are synthesized from 35‐ to 250‐ nm thickness, revealing a transition from a fully ferroelectric state to coexisting ferroelectric and antiferroelectric phases with increasing thickness. The electrical performance of this phase coexistence is analyzed through positive‐up negative‐down and first‐order reversal curve measurements. Further increasing thickness leads to a fully ferroelectric state due to a strain relief mechanism that suppresses the antiferroelectricity. The potential of engineering competing ferroic orders in NaNbO₃for multiple applications is evaluated, reporting significantly enhanced recoverable energy density (20.6 J cm⁻³at 35 nm) and energy efficiency (90% at 150 nm) relative to pure bulk NaNbO₃as well as strong retention and fatigue performance with multiple accessible polarization states in the intermediate thickness films. 

   more » « less
5. Couplings of Polarization with Interfacial Deep Trap and Schottky Interface Controlled Ferroelectric Memristive Switching

   https://doi.org/10.1002/adfm.202000664  

   Chen, Aiping; Zhang, Wenrui; Dedon, Liv_R; Chen, Di; Khatkhatay, Fauzia; MacManus‐Driscoll, Judith_L; Wang, Haiyan; Yarotski, Dmitry; Chen, Jun; Gao, Xingsun; et al (August 2020, Advanced Functional Materials)

   Abstract Memristors with excellent scalability have the potential to revolutionize not only the field of information storage but also neuromorphic computing. Conventional metal oxides are widely used as resistive switching materials in memristors. Interface‐type memristors based on ferroelectric materials are emerging as alternatives in the development of high‐performance memory devices. A clear understanding of the switching mechanisms in this type of memristors, however, is still in its early stages. By comparing the bipolar switching in different systems, it is found that the switchable diode effect in ferroelectric memristors is controlled by polarization modulated Schottky barrier height and polarization coupled interfacial deep states trapping/detrapping. Using semiconductor theories with consideration of polarization effects, a phenomenological theory is developed to explain the current–voltage behavior at the metal/ferroelectric interface. These findings reveal the critical role of the interaction among polarization charges, interfacial defects, and Schottky interface in controlling ferroelectric resistive switching and offer the guidance to design ferroelectric memristors with enhanced performance. 

   more » « less