Multilayer Ferroelectric Films Research Articles

Ultrahigh output energy density of explosive-energy-conversion devices assembled from multilayer ferroelectric films

A multilayer PMN–PZT + 2Li film stack with a volume of 0.9 cm3 could generate a current of 3156 A, exceeding that of existing ferroelectric ceramics by 2 orders of magnitude.

Interlayer Coupling Enhanced Energy Storage Performance in a Flexible BMT-BTO/BMT Multilayer Ferroelectric Film Capacitor

Flexible ferroelectric capacitors with high energy density and storage efficiency are highly desirable in the next generation of flexible electronic devices. To develop high-performance ferroelectric capacitors, a conventional approach is chemical modification. Here, a novel approach of interlayer coupling is proposed to achieve high energy storage performance in BiMg0.5Ti0.5O3-BaTiO3/BiMg0.5Ti0.5O3 (BMT-BTO/BMT)N multilayer ferroelectric films fabricated on flexible mica substrates via a sol-gel coating method. The interlayer electrostatic coupling between the ferroelectric BMT and relaxor ferroelectric BMT-BTO layers leads to small remnant polarization and large breakdown field strength, resulting in an outstanding energy storage density of ∼106.8 J cm-3 and a good efficiency of ∼75.6% in the multilayer thin films. Further, the energy storage performance remains stable in a wide range of temperatures (25-200 °C) and frequencies (500 Hz to 10 kHz) after 108 electrical loading cycles. The energy storage performance also has no obvious deterioration when the multilayer film experiences 104 mechanical bending cycles with a bending radius of 4 mm. The approach proposed in the present work should be generally implementable in other multilayer flexible ferroelectric capacitors and offers a novel avenue to enhance energy storage performance by tuning the interlayer coupling.

A review of ferroelectric materials for high power devices

Compact autonomous ultrahigh power density energy storage and power generation devices that exploit the spontaneous polarization of ferroelectric materials are capable of producing hundreds of kilovolt voltages, multi-kiloampere currents, and megawatt power levels for brief interval of time. The storage life of these devices is four orders of magnitude longer than that for electrochemical batteries and electrochemical capacitors. Herein is an up to date survey of ferroelectric materials used for these high power devices. Several types of ferroelectric ceramics possess the ability to be depolarized under adiabatic compression and can be successfully used for high power applications. In addition to bulk ferroelectric ceramics, multilayer ferroelectric films are very efficient materials for high power systems. Of particular importance is the ability of relaxor ferroelectric single crystals to produce significantly higher electric charge density and energy density than ceramics, making them promising materials for high power applications. Also provided is a brief survey of recent developments of ferroelectric materials for high energy density and power density dielectric capacitors. Numerous ceramics have been developed, including antiferroelectric and relaxor antiferroelectric solid solutions, providing high energy density and efficiency simultaneously.

The Field Effect in a Metal–Ferroelectric–Semiconductor System of Multilayer Ferroelectric Films with Various Structure Types

The ability to grow the interfacial defect-poor Sr0.5Ba0.5Nb2O6 + Ba0.2Sr0.8TiO3 and Ba0.8Sr0.2TiO3 + Ba0.4Sr0.6TiO3 ferroelectric films onto the doped silicon substrates is discussed. A study of piezo-response via the quasi-static method (using the electrode area of 0.07 mm2) reveals that heterostructures possess an initial polarized ferroelectric state with a spontaneous polarization vector perpendicular to the substrate at any type of Si conductivity. The polarized state is established to refer to two-dimension stresses in the ferroelectric, which is tunable through a preprepared BaxSr1 – xTiO3 onto a sublayer substrate as well as to a thickness of this sublayer. Polarization switching in Sr0.5Ba0.5Nb2O6/Si and Ba0.8Sr0.2TiO3/Si heterostructures under the external field arises at only using the barium–strontium titanate sublayer predeposited onto silicon. A 15% decrease in switching polarization in Ba0.8Sr0.2TiO3/Ba0.4Sr0.6TiO3/Si structures is observed after 500 h.

Electric and ferroelectric properties of a multilayer film of Nd<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> and Bi<sub>3.25</sub>La<sub>0.75</sub>Ti<sub>3</sub>O<sub>12</sub> for use as a ferroelectric field effect transistor

Ferroelectric materials are of interest due to their applications, such as in ferroelectric field effect transistor memory (FeFET). For this application, reducing retention time according to the leakage current is an important matter. Ferroelectric materials are able to be improved through multilayer fabrication of ferroelectric films. This study investigated multilayer ferroelectric thin films using strong candidate ferroelectric materials such as Bi 3.25 La 0.75 Ti 3 O 12 (BLT) and Nd 2 Ti 2 O 7 (NT). The ferroelectric materials were prepared with a stable interface using broad stoichiometry, without occurrence of a secondary phase or a disruption in stoichiometry. For the characterization of BLT, NT, and BLT/NT multilayer ferroelectric films, various analyses and measurements were carried out, including X-ray diffraction, X-ray photoelectron spectroscopy, current-voltage and polarization-voltage. The multilayer ferroelectric films showed improved ferroelectric properties using multilayer fabrication with a highly insulating ferroelectric film.

On the permittivity of multilayer ferroelectric films

The effective permittivity of dielectric-ferroelectric multilayer films has been investigated. The features of the effective permittivity behavior that are related to the inhomogeneity of the dielectric properties of these materials and the size effects are discussed.

Review Composite and multilayer ferroelectric thin films: processing, properties and applications

This paper reviews recent developments in processing, properties and applications of composite and multilayer ferroelectric thin films. Methods such as physical vapor deposition, chemical vapor deposition and sol-gel, for the processing of composite and multilayer ferroelectric films are described. Among the techniques reviewed for the fabrication of multilayer ferroelectric films, molecular beam epitaxy and atomic layer metal-organic chemical vapor deposition are the most suitable techniques for the deposition of superlattices with atomically sharp interface. As an efficient and quick way, pulsed-laser deposition has been widely used for the preparation of ferroelectric multilayers and heterostructures. Superior dielectric properties have been reported for sol-gel-derived micrometer-thick ceramic/ceramic composite ferroelectric films. Properties of multilayer ferroelectric films vary as a function of periodicity, which can be exploited for the development of various electronic devices. Enhanced characteristics of composite and multilayer films with selected examples from recent literature and the origin of enhancement are discussed and summarized. Finally, applications of the materials for the development of various electronic devices are also presented.

Fabrication of multilayer ferroelectric films

Multilayers of strontium bismuth tantalate (Sr0.9Bi2.2Ta2O9, SBT) with bismuth titanate (Bi4Ti3O12, BT), and SBT and strontium bismuth niobate (Sr0.9Bi2.2Nb2O9, SBN) with BT were prepared by chemical solution deposition (CSD). The CSD solutions were a mixture of strontium, tantalum, niobium and titanium butoxyethoxides and bismuth ethylhexanoate dissolved in butoxyethanol. SBT films were fabricated and annealed at 800°C for 60 min. Generally, all capacitors of the SBT films tested had low resistance with as-deposited Pt top electrodes and no ferroelectricity could be measured. After a post electrode anneal at 800°C for 30 min, a percentage of capacitors could be tested for ferroelectricity, and a 2Pr of 15 μC/cm2at 3V was typically measured. Multilayer SBT, and SBT and SBN with BT were rapidly thermally annealed for a total (including post electrode anneal) of 20–40 min at 750°C. The multilayer SBT and SBN with BT, and SBT with BT films exhibited a wide range of 2Pr values ranging from 2–14 μC/cm2at 3V but had a larger percentage of measurable capacitors after post electrode anneal than the SBT only films. In addition, no fatigue was observed after 1011cycles in a SBT with BT multilayer structure.