Multilayer Capacitors Research Articles

The interface effects on the breakdown strength of multilayer PVDF-based capacitors

Exploring polymer-based films with high energy density and low cost is important, because they have potential applications in flexible electronic equipment. In this paper, we investigated the evidence of structure changes in multilayer films and elaborated on the part of interface effects on dielectric properties. Polyvinylidene fluoride (PVDF) and poly (vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) were spun-coated to form multilayer polymer films. The PVDF/P(VDF-HFP)/PVDF multilayer film has an improved breakdown strength of 4492 kV cm−1 and a discharged energy density of 6.24 J cm−3. According to experimental results, an increase in breakdown strength is caused by an improvement in leakage current and a reduction in ferroelectric β-phase. The high breakdown strength of multilayer films contributes to the improvement of energy storage density. This work will provide a process method for creating low cost, defect-free, high energy density polymer capacitors.

Tuning dielectric properties of sputtered BaTiO3 thin film capacitors via multilayering with SrTiO3

[Formula: see text]/[Formula: see text] (BTO/STO) multilayer films were successfully prepared on (La, Sr)[Formula: see text]-coated (100) [Formula: see text] substrates by using a radio-frequency (RF) magnetron sputtering process at [Formula: see text]C. Benefiting from the flexible deposition configuration of a multi-target sputtering system, we were able to tune the dielectric properties of the multilayer film by varying the number of multilayer periods [Formula: see text] and the individual layer thickness [Formula: see text]. It was found that, in a superlattice-like structure ([Formula: see text]=4 nm, [Formula: see text] 10 unit cells), the dielectric constant increased and the loss tangent decreased with an increasing [Formula: see text], especially in the high frequency range ([Formula: see text]Hz). This can be attributed to a reduced volumetric contribution to the dielectric property from the leaky interface capacitor layer, which lies between the multilayer film and the (La, Sr)[Formula: see text] electrode. On the other hand, as the individual layer thickness [Formula: see text] exceeds the superlattice limit ([Formula: see text]=8 nm, [Formula: see text] 20 unit cells), the superlattice strain effect disappeared and the dielectric constant value dropped by [Formula: see text]50%. However, owing to the reduced number of interfaces and associated defects, the dielectric loss of the multilayer film with a larger period was reduced significantly, as compared to its superlattice counterpart with the same thickness and more periods. The dielectric loss power density of the former was about one order of magnitude lower than that of the latter. These observations provide a solid foundation for using RF magnetron sputtering as an effective method to prepare various forms of multilayer film capacitors for integrated device applications.

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.

Large harvested energy with non-linear pyroelectric modules

Coming up with sustainable sources of electricity is one of the grand challenges of this century. The research field of materials for energy harvesting stems from this motivation, including thermoelectrics1, photovoltaics2 and thermophotovoltaics3. Pyroelectric materials, converting temperature periodic variations in electricity, have been considered as sensors4 and energy harvesters5–7, although we lack materials and devices able to harvest in the joule range. Here we develop a macroscopic thermal energy harvester made of 42 g of lead scandium tantalate in the form of multilayer capacitors that produces 11.2 J of electricity per thermodynamic cycle. Each pyroelectric module can generate up to 4.43 J cm−3 of electric energy density per cycle. We also show that two of these modules weighing 0.3 g are sufficient to sustainably supply an autonomous energy harvester embedding microcontrollers and temperature sensors. Finally, we show that for a 10 K temperature span these multilayer capacitors can reach 40% of Carnot efficiency. These performances stem from (1) a ferroelectric phase transition enabling large efficiency, (2) low leakage current preventing losses and (3) high breakdown voltage. These macroscopic, scalable and highly efficient pyroelectric energy harvesters enable the reconsideration of the production of electricity from heat.

Structural and Impedance Analysis of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 Ceramic

Background: Since (1-x)[Pb(Mg1/3Nb2/3)O3]-(x)PbTiO3 (PMN-PT) ceramic has a high dielectric constant and piezoelectric coefficient, it has been widely investigated for profound applications in electro-optical devices, sensors, multilayer capacitors and actuators. Objectives: The objective of this paper is to study the structural and electrical properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (0.7PMN-0.3PT) ceramic to understand the biphasic structural nature using Rietveld Refinement. Also, it characterises the type of conduction process as well as the role of grain and grain boundary resistance in the material on the basis of electrical properties such as impedance and modulus to understand the relaxation process. Methods: 0.7PMN-0.3PT is synthesised by mixed oxide method using PbO, MgO, Nb2O5 and TiO2 as precursor materials. Results: The XRD data reveals the biphasic structure of the tetragonal phase with the space group of P4mm and the monoclinic phase with the space group of Pm. The complex impedance analysis clearly represents the effect of grain on the overall resistance and departs from normal Debye-type behaviour. Also, the resistance is found to decrease with temperature, thereby confirming the semiconducting nature of the sample. The presence of long as well as short-range mobility of charge carriers is confirmed from the modulus and impedance analysis. The influence of long-range motion is observed at high temperatures and of short-range motion at low temperatures. Conclusion: XRD analysis confirmed the biphasic structure of the M+T phase. The frequencydependent modulus and impedance spectroscopy show the presence of a relaxation effect in the ceramic which is found to increase with temperature. The Nyquist plot shows that the resistance is decreased with temperature, thereby confirming the NTCR behaviour in the studied sample.

Efficiency of energy harvesting and storage using a multilayer capacitor based on BaTi0.86Sn0.14O3 ferroelectric lead-free ceramics

The study of the parameters of energy harvesting and storage in the lead-free solid solution BaTi0.86Sn0.14O3 (BTSnO) was performed. The permittivity shows the behavior similar to a diffuse phase transition with the critical exponent γ = 1.84, which is close to the value characteristic of relaxors. Large values of the recoverable energy density, Wrec=(5.8–7.0)∙104 J/m3, and the energy storage efficiency coefficient, η=(82–94) %, are implemented in a wide temperature range, 30–87°С, at a low electric field, E = 18.5 kV/cm. For the first time, the analysis of the Olsen cycle was performed using two phase diagrams: polarization – electric field and entropy – temperature. A fairly good agreement was found between the values of the energy conversion density, ND ≈ 0.15 J/cm3, which was determined using two approaches. A universal parameter is proposed for comparing the energy harvesting density for the materials studied in different ranges of temperature and electric fields.

Materials efficiency of electrocaloric lead scandium tantalate multilayer capacitors

Electrocaloric materials in the shape of multilayer capacitors are excellent working bodies to build cooling devices as they can exhibit large changes in temperature triggered by changes in voltage over large range of temperatures. However, high electric fields are required to drive such a large effect and yet, their efficiency has been overlooked. Here we report on the materials efficiency of lead scandium tantalate multilayer capacitors. Hence, we show that they can exchange 25 times more heat than the electrical work required to generate this heat. Besides, we observed that these multilayers capacitors are four times less efficient than lead scandium tantalate bulk ceramics for the same heat exchanged, though they exhibit a large electrocaloric effect on a much larger temperature range. Moreover, their efficiency is comparable to Gd, the prototypical magnetocaloric material. This work ultimately provides an extensive picture of the pros and cons of lead scandium tantalate.

Study of silicon rich oxide light emitter capacitors using textured substrates by metal assisted chemical etching

Mono and multilayer silicon rich oxide light-emitting capacitors (SRO-LEC) were fabricated using both polished and textured Si substrates. The textured substrate surface was treated by metal-assisted chemical etching (MACE) for 10 s and 20 s forming nanoneedles. Monolayer devices fabricated using textured substrates required lower energy to emit light and present at least 40% higher emission intensity than non-textured substrates. On the other hand, multilayer devices fabricated on textured and polished substrates showed that both LECs required similar energy to start the emission, however, after the bias is increased up to 5.5 MV/cm the textured LECs presented 36% higher emission intensity. The evidence shows that the electric field is screened by the nanocrystals in the SRO with Ro = 10 at electric fields lower than 5.5 MV/cm.

Mathematical simulation for the formulation of synthesis of PMN-PZN ceramics at different sintering temperature with reliability of density measurement

This paper discusses the approach to formulate mathematical model (MM) for synthesis of any ceramic and to decide reliability of density measurement. In the research of basic science, the majority of operations are still executed manually which needs to be focused and develop a mathematical relation which simulate the real input and output data directly. The advantages and limitations of the developed mathematical models are identified and the models are classified in terms of range of application and goals. In this study, a generalized experimental data based model developed to simulate the contemporary techniques for the purpose of study, compression, inducing generalized approach for the mathematical model of ceramic synthesis. The findings indicate that the topic understudy is of great importance, as no such approach of experimental data based mathematical simulation is adopted for the formulation of synthesis of ceramics so far. Thus the results of this experimental research would be useful to industry for manufacturing of multilayer capacitors.

Ionizing radiation response of bismuth titanate-based metal-ferroelectric-semiconductor (MFS) type capacitor

In this study, the ionizing radiation (gamma-irradiation) response of the metal-ferroelectric-semiconductor (MFS) type capacitors whose interfacial layer is bismuth titanate (Bi4Ti3O12), which is from the Aurivillius family, was investigated. The capacitance-voltage (CV) and conductance-voltage (G/ω-V) characteristics and the device parameters derived from these characteristics provide essential information about the radiation response. Therefore, MFS-type capacitors in which their Schottky/rectifier contacts Au and interfacial layer Bi4Ti3O12 (BTO) were prepared and exposed to various doses of gamma-rays. The voltage-dependent C and G/ω data were obtained before irradiation and after some irradiation doses using the Hewlett Packard Impedance Analyzer. Experimental results showed that the CV curves exhibited multilayer capacitor behavior before and after radiation rather than conventional Schottky structures due to the very thin Silicon dioxide (SiO2) interlayer at the BTO/Si interface, which was assumed to form during the annealing of BTO films in air ambient. On the other hand, the C-G/ω-V curves exhibited asymmetric and hysteretic behavior because of the different electrical properties at the bottom and top interfaces and the natural ferroelectric behavior of the BTO. On the other hand, considering the radiation effects, the C-G/ω-V characteristics and other device parameters did not show any significant changes at the 5 kGy irradiation dose, but significant differences were observed in all parameters at the 22 kGy dose. Therefore, it can be concluded that these MFS-type structures with the BTO interlayer can be used as a capacitor or radiation sensor at doses around 5 kGy and below 22 kGy. However, it is not recommended to use them as capacitors at doses close to 22 kGy due to the large capacitive change (approximately tenfold decrease) at this dose. Besides, the tendency of the device to deteriorate at 22 kGy doses indicates that it is not suitable for use as a capacitor or radiation sensor above 22 kGy gamma-irradiation doses.

High-Performance PbZrO3-based antiferroelectric multilayer capacitors based on multiple enhancement strategy

Antiferroelectric (AFE) materials are thought to be one of the most promising candidates for energy storage application owing to their large polarization difference between maximum polarization and remanent polarization originating from unique electric field-induced phase transition, but the large polarization hysteresis leads to an inferior energy efficiency, which restricts their applications in advanced pulsed power devices. Herein, we propose a multiple enhancement strategy of composition and structural modification to solve this problem. The (Pb0.875La0.05Sr0.05)(Zr0.695Ti0.005Sn0.3)O3 (PLSZTS) antiferroelectric ceramic and corresponding multilayer ceramic capacitor (MLCC) are fabricated. A low hysteresis is obtained via composition optimization. Moreover, multilayer ceramic constructing improves significantly breakdown strength (BDS) due to decreased thickness of dielectric layer. An ultrahigh recoverable energy density (Wdis) of 19.9 J/cm3, together with a high energy efficiency (η) of 96.4% are achieved synchronously at an electric field of 85 kV/mm. In addition, the studied MLCCs also possess outstanding discharge energy storage properties with a high discharge energy density (Wdis) of 15.4 J/cm3 and a large power density (PD) of 170.5 MW/cm3, a wide temperature range of 20–120 °C, and strong fatigue endurance after 3000 cycles. The present research results not only offer a potential candidate for high-power energy storage devices, but also, more importantly, develop a universal approach for optimizing the overall energy storage performance.

Flex‐circuit resonant chip with Y5V multilayer capacitor for wireless temperature tracking

This paper reports the first wireless thermometric device enabled using a surface-mount capacitor microchip as the sensing element, offering a low-cost, disposable, and flexible sensor potentially suitable for a wide range of application areas. The device is developed in the form of a resonant-circuit chip, in which a Y5V-type multilayer capacitor microchip that exhibits significant temperature dependence serves as a thermoresponsive element that varies the resonant frequency of the circuit upon a temperature change. The wireless sensor chips prototyped in conjunction with the flex-circuit technology are tested to show their intended function with the frequency responses of up to 129 kHz/°C for ambient temperature variations. Wireless temperature tracking of a fluid-flowing channel is experimentally demonstrated using the prototype.

Dielectric and ferroelectric properties of X8R perovskite barium titanate for application in multilayered ceramics capacitors

Dielectric and ferroelectric properties of X8R perovskite barium titanate for application in multilayered ceramics capacitors

Flexible multilayer lead-free film capacitor with high energy storage performances via heterostructure engineering

The immense potential of flexible energy storage materials applied in wearable electronic devices has stimulated a lot of science researches on manufacturing technology and performance optimization. Herein, an all-inorganic flexible ferroelectric film with multilayer heterostructure is prepared based on Mn doped Bi0.5Na0.5TiO3BiNi0.5Zr0.5O3 (Mn:BNT-BNZ) and Bi0.5Na0.5TiO3BiZn0.5Zr0.5O3 (BNT-BZZ) relaxor ferroelectrics. A win-win situation of breakdown strength and polarization is achieved in the Mn:BNT-BNZ/BNT-BZZ multilayer film with the stacking period N = 3, of which energy density and efficiency reach 80.4 J/cm3 and 62.0% respectively. It is proposed that the excellent energy storage performances are attributed to the synergistic effect of the electric field amplification effect, interface blocking effect and the polarization coupling effect based on the multilayer heterostructure. Moreover, the flexible ferroelectric film exhibits outstanding temperature (25–205 °C), frequency (0.5–5 kHz) stability and antifatigue property (1 × 108 cycles), and can well maintain stable performance at different tensile/compressive bending radii (10–5 mm) and even after 104 bending cycles with a fixed bending radius of 3 mm. This work opens up a promising route to the development of flexible energy storage materials.

Synthesis and characterizations of ‘Ca’-doped Ba(FeNb)0.5O3 for device application

ABSTRACT BaFe0.5Nb0.5O3 (BFN) has emerged as a potential perovskite with excellent dielectric properties over a wide range of frequencies and temperatures. The present work reports the synthesis of Ba0.96Ca0.04(FeNb)0.5O3 perovskite by solid-state reaction method. XRD profile confirms the formation of a single-phase new compound with an orthorhombic crystal symmetry. SEM and EDX analysis techniques are applied to examine its microstructure and purity respectively. The detailed dielectric behavior of the prepared material is analyzed within the frequency range 100 Hz - 5 MHz and temperature range 25 – 400 °C. High dielectric constant and low tangent loss suggest that the material may be used to design multilayer capacitor and other electronic devices. Impedance spectroscopy analysis is an additional feature used for investigating electrical properties of the prepared material. The hopping type of charge carriers are responsible for conduction mechanism in the material.

Ultrahigh Temperature Lead-Free Film Capacitors via Strain and Dielectric Constant Double Gradient Design.

With the development of miniaturization, lightweight and integration of electronic devices, the demand for high-temperature dielectric capacitors is becoming urgent. Nevertheless, the breakdown strength and polarization are deteriorated at high temperatures due to the thermal energy assisting the electron transport and impeding the dipole alignment. Here, a structure of capacitor with double gradients of dielectric constant gradient and strain gradient is designed to achieve high breakdown strength, high working temperature, and high energy storage density simultaneously. It is found that the designed structure of BaHf0.17 Ti0.83 O3 /1mol% SiO2 doped BaZr0.35 Ti0.65 O3 /0.85BaTiO3 -0.15Bi(Mg0.5 Zr0.5 )O3 exhibits excellent energy storage performance. The energy storage density of 127.3 J cm-3 with an energy storage efficiency of 79.6% is realized in the up-sequence multilayer with period N= 2 at room temperature. Moreover, when the working temperature varies from -100 to 200 °C, the energy storage density of the N= 4 capacitor keeps stably at 84.62 J cm-3 with an energy storage efficiency 78.42% at 6.86 MV cm-1 . All these properties promise great potential applications of the designed multilayer capacitors with the double gradients in harsh environments, and the design principle can be applicable to other systems to boost working temperature.

Spectroscopic study of Co-doped CaCu3Ti4O12

Calcium-copper titanate has been thoroughly studied by scientists around the world for several decades due to the manifestation of colossal dielectric permeability values (ε ~104 –105) in wide frequency ranges (102 –106 Hz) and temperature ranges (100 – 600 K), showing neither ferroelectric nor relaxor properties. Due to the unique dielectric characteristics of calcium-copper titanate (CCTO), materials based on it are promising for the manufacture of multilayer capacitors and microwave devices. Restrictions on the practical use of CCTO are caused by high dielectric losses. Electrophysical characteristics are optimized by modifying the CCTO composition, partially replacing copper, titanium and calcium cations. Good dielectric properties are demonstrated by the CCTO ceramics doped with cobalt atoms. Co-doped CaCu3Ti4O12 was obtained by solid phase synthesis method. The samples are characterized by a grain microstructure; a thin layer of CuO is fixed in the intergranular space. From the interpretation of the obtained XPS- and NEXAFS 2p-spectra of Co-doped CaCu3Ti4O12 and the corresponding oxides it can be concluded that in the Co-doped ССТО atoms of copper and calcium have a charge state of +2, atoms of titanium — +(4 − δ), and cobalt atoms mainly +2 with some fraction of Co (III) in the high spin state. The Co-doped sample FTIR spectrum clearly captures the absorption bands in the fingerprint area at ≈408, 488, 539 cm−1, which are typical for ССТО.

Magnetic and Dielectric Study of Ceramic Nanocomposite Nickel Ferrite and Barium Titanate Compounds

Owing to high dielectric constants and coupled magnetic properties at room temperature, multiferroics related materials have wide application in many fields like multi-layer ferroic capacitors and multifunctional devices. Nickel ferrite, barium titanate composite is prepared from co-precipitation method and sintered at high temperature (1273 K). Intrinsic stretching vibrations observed in FTIR spectra at 594 cm−1. X-ray measurements detected the presence of their single phases (tetragonal perovskite crystal). Variations of AC dielectric constant in these samples have been studied. The influence of the phase content on the dielectric constant and loss tangent conductivity was also studied. The AC measurement yields smaller variations at a low range of frequency and more variations in higher frequency ranges indicate amplification of confined states with the availability of large charge carriers. A magnetic measurement reveals that the soft ferromagnetic properties of 68.356 emu g−1 and 20.465 emu g−1 at room temperature.

Investigation of multifunctional characteristics in SmFeO3-BaTiO3 perovskite system for devices

The polycrystalline ceramic (SmFeO3)0.5 (BaTiO3)0.5 (SF-BT) is synthesized by high temperature solid state reaction method. The sample is investigated for its multifunctionality by analyzing its structural, dielectric, electrical and multiferroic properties. The XRD patterns and the rietveld refinement confirm the single phase forming of the compound in the tetragonal symmetry with P4mm space group. The dielectric properties of the material analyzed on the basis of Maxwell-Wagner phonological model. The room temperature dielectric constant reveals material can be useful for multilayer capacitor. Complex impedance and modulus studies confirm non-Debye type, negative temperature coefficient of resistance (NTCR) behavior and the electrical resistance in the material is only due to contribution grains. The short-range mobility of charge carriers is responsible for different types relaxation mechanism in the material. The Multiferroic studies show the existence of room temperature ferroelectric (ferroelectric (2P = 1.17 μC/cm2, EC = 0.65 kV/cm) and ferromagnetism (Mr = 0.77emu/g at HC = 1.1 kOe) properties in the material. The study reveals the leakage behavior of the material is reduced significantly and enhanced Multiferroic character for microelectric and memory devices.

Dielectric and magnetic behavior of Sr-modified vanadium based double perovskite

The Sr-modified vanadium-based double perovskite Ba1.5Sr0.5FeVO6 was synthesized by conventional solid solution casting procedure at an optimized temperature 1225 °C. The preliminary structural investigation was carried out through X-ray diffraction (XRD) and scanning electron microscope (SEM). Fourier transforms infrared (FTIR) technique was utilized to distinguish among the different modes of vibration of the elements in the compound. The band gap (2.76 eV) of the material was evaluated through the UV–Visible spectroscopy technique. Dielectric and related measurements were conducted through LCR meter in the frequency range (100 Hz–5 MHz) under the temperature range (25 °C-–500 °C). Room temperature dielectric constant (εr ~ 500) and tangent loss (tanδ ~ 0.08) at 10 kHz suggests material may be useful for multilayer capacitor and other storage devices. Non-destructive impedance spectroscopy (IS) techniques have been adopted for electrical characterization. In addition to the IS further electrical features have been investigated through ac and dc conductivity spectra . For magnetic behavior of the material (M-H) hysteresis was carried out at room temperature to investigate the magnetic properties of the material.