Impact of fatigue behavior on energy storage performance in dielectric thin-film capacitors

The polarization hysteresis loops and the dynamics of domain switching in ferroelectric Pb(Zr_0.52Ti_0.48)O₃ (PZT), antiferroelectric PbZrO₃ (PZ) and relaxor-ferroelectric Pb_0.9La_0.1(Zr_0.52Ti_0.48)O₃ (PLZT) thin films deposited on Pt/Ti/SiO₂/Si substrates were investigated under various bipolar electric fields during repetitive switching cycles. Fatigue behavior was observed in PZT thin films and was accelerated at higher bipolar electric fields. Degradation of energy storage performance observed in PZ thin films corresponds to the appearance of a ferroelectric state just under a high bipolar electric field, which could be related to the nonuniform strain buildup in some regions within bulk PZ. Meanwhile, PLZT thin films demonstrated fatigue-free in both polarization and energy storage performance and independent bipolar electric fields, which are probably related to the highly dynamic polar nanodomains. More importantly, PLZT thin films also exhibited excellent recoverable energy-storage density and energy efficiency, extracted from the polarization hysteresis loops, making them promising dielectric capacitors for energy-storage applications.     

Electrospinning and characterization of magnetoelectric NdFeO3–PbZr0.52Ti0.48O3 Core–Shell nanofibers

A core–shell nanofiber with a neodymium orthoferrite (NdFeO₃) core and lead zirconium titanate (PbZr_0.52Ti_0.48O₃) shell was prepared in this study using the sol-gel electrospinning method. Structural properties of the nanofiber were analysed using the X-ray diffraction (XRD) method, which revealed that a perovskite structure was formed. The strain was calculated using Williamson-Hall (W–H) plot. Functional groups of the nanofiber were studied using Fourier transform infrared (FTIR) spectroscopy. Morphological studies revealed the core diameter of the nanofiber to be 65 nm and its shell diameter to be 128 nm. The elemental analysis of core-shell nanofiber was made using Energy Dispersive X-ray Spectroscopy (EDS) which proved the formation of NdFeO₃ and PbZr_0.52Ti_0.48O₃ composite in the stoichiometric ratio. Topography analysis using atomic force microscopy found the average fibre diameter to be 135 nm. The nanofiber exhibited antiferromagnetic behaviour, with a saturation magnetization of 0.48 emu/g. Dynamic contact electrostatic force microscopy (DC-EFM) studies revealed that the nanofiber showed domain-switching behaviour. The ferroelectric hysteresis plots showed that the nanofiber exhibited a maximum polarization of 5.45 μC/cm² at 20 kV/cm. Also, its dielectric constant was 268 at 100 Hz. The leakage current study revealed a butterfly-shaped J-E loop, which further proved the ferroelectric behaviour of the nanofiber. The mechanism behind the leakage current was identified to be the Schottky emission. The P-E loops recorded under external magnetic fields of different strengths exhibited variations in the polarization, indicating the presence of cross-coupling between electric and magnetic order parameters. Because of the high dielectric constant displayed by the magnetoelectrically active NdFeO₃–PbZr_0.52Ti_0.48O₃ core–shell nanofiber, it can be a promising candidate for a number of applications, such as data storage devices, multimedia devices, spintronics and magnetic field sensors.     

High energy density capacitors based on 0.88BaTiO3–0.12Bi(Mg0.5, Ti0.5)O3/PbZrO3 multilayered thin films

Multilayered thin films consisting of both 0.88BaTiO₃–0.12Bi(Mg_0.5,Ti_0.5)O₃ ferroelectric layers and PbZrO₃ antiferroelectric layers were prepared by sol–gel method, exhibiting high dielectric permittivity, large polarization, high recoverable energy storage density and high energy storage efficiency. A maximum polarization of 93 μC/cm², recoverable energy storage density of 24.7 J/cm³ and energy storage efficiency of ~60% have been achieved at an electric field of 1050 kV/cm. Furthermore, the energy storage performance of the multilayered thin films was improved by modified layer-by-layer annealing process, where larger polarization (115 μC/cm²), higher recoverable energy storage density (33 J/cm³) and higher energy storage efficiency (~70%) were obtained.     

Effect of annealing temperature on ferroelectric electron emission of sol–gel PZT films

In this work, the influence of annealing temperature on the ferroelectric electron emission behaviors of 1.3-μm-thick sol–gel PbZr_0.52Ti_0.48O₃ (PZT) thin film emitters was investigated. The results revealed that the PZT films were crack-free in perovskite structure with columnar-like grains. Increasing annealing temperature led to the growth of the grains with improved ferroelectric and dielectric properties. The remnant polarization increased slightly from 35.3 to 39.6 μC/cm² and the coercive field decreased from the 56.4 to 54.6 kV/cm with increasing annealing temperature from 600 to 700 °C. The PZT film emitters exhibited remarkable ferroelectric electron emission behaviors at the threshold voltage above 95 V. The film annealed at 700 °C showed a relatively lower threshold voltage and higher emission current, which is related to the improved ferroelectric and dielectric properties at higher annealing temperature. The highest emission current achieved in this work was around 25 mA at the trigger voltage of 160 V.     

Oxygen plasma-assisted ultra-low temperature sol-gel-preparation of the PZT thin films

PbTi_1-xZr_xO₃ (PZT) thin films prepared by sol-gel method have paid much attention due to the excellent performances in piezoelectric, dielectric, ferroelectric and electro-optical. However, the high crystallization temperature of the PZT thin films restricts the compatibility with modern COMS technology. In this work, PbZr_0.52Ti_0.48O₃ (PZT) ferroelectric thin films were successfully prepared by sol-gel method at an ultra-low temperature (～450 °C) in an oxygen plasma-assisted environment. A large spontaneous polarization ～30 μC/cm² and a large dielectric breakdown ～2,900 kV/cm were obtained in the sample annealed at 450 °C for 25 h. We believe that the oxygen plasma-assisted ultra-low temperature (OPAULT) annealing process is a promising way for the sol-gel technology applied in the modern COMS devices.     

Enhancement of energy storage and thermal stability of relaxor Pb0.92La0.08Zr0.52Ti0.48O3-Bi(Zn0.66Nb0.33)O3 thick films through aerosol deposition

Relaxor ferroelectric Pb_0.92La_0.08Zr_0.52Ti_0.48O₃ (PLZT 8/52/48) has been studied widely for applications to high energy storage capacitors because of its polarization-electric (P-E) field hysteresis. On the other hand, its energy storage characteristics are unsatisfactory because the dielectric properties deteriorate with temperature. In the present study, a dense nano-composite thick film (∼5 μm) was fabricated by the aerosol deposition (AD) of mixed powders of BZN [Bi(Zn_0.66Nb_0.33)O₃] corresponding to 0, 5, and 10 at.% with lanthanum-doped lead zirconate titanate ceramics (PLZT) at room temperature, followed by post-annealing for crystallization recovery. The composition of 0.95(Pb_0.92La_0.08Zr_0.52Ti_0.48O₃)-0.05Bi(Zn_0.66Nb_0.33O₃) PLZT-BZN5 was made artificially, which accommodates the coexistence of two different phases, demonstrating superior energy storage performance. The 550°C-annealed PLZT-BZN5 film showed a superior energy density of 14.7 J/cm³ under an electric field of 1400 kV/cm and an efficiency of 81%. The PLZT-BZN5 film also exhibited low dielectric loss and improved temperature stability.     

Growth of the ternary Pb(Mn,Nb)O3–Pb(Zr,Ti)O3 thin film with high piezoelectric coefficient on Si by RF sputtering

In this study, ternary ferroelectric 0.06Pb(Mn_1/3Nb_2/3)O₃–0.94Pb(Zr_0.48Ti_0.52)O₃ (PMN–PZT) thin film with high piezoelectric coefficient were grown on La_0.6Sr_0.4CoO₃-buffered Pt/Ti/SiO₂/Si substrate by RF magnetron sputtering method. The phase and domain structure along with the macroscopic electrical properties were obtained. Under the optimized temperature of 550°C and sputtering pressure 0.9 Pa, the PMN–PZT film owned large remnant ferroelectric polarization of 62 μC/cm². In addition, the PMN–PZT film had polydomain structures with fingerprint-type nanosized domain patterns and typical local piezoelectric response. Through piezoelectric force microscopy, the PMN–PZT thin film at nanoscale exhibited obvious domain reversal when subjected to in situ poling field. It was further found that the quasi-static piezoelectric coefficient of the PMN–PZT thin film reached 267 pC/N, which was about twice to that of the commercial PbZrO₃–PbTiO₃ (PZT) thin film. The optimized relaxor ferroelectric thin film PMN–PZT on silicon with global electrical properties shows great potential in the piezoelectric micro-electro-mechanical systems applications.     

Cyclic Electrical Energy Harvesting Using Mechanical Confinement in Ferroelectric Ceramics

Present study introduces a novel energy conversion cycle for giant electro‐mechanical energy conversion using ferroelectric materials. The proposed cycle is used to perform indirect measurements for harnessable energy densities of two well‐known configurations ((0.5PbZrO₃‐0.5Pb(Ni_1/3Nb_2/3)O₃: (PZ‐PNN) and 0.9Pb(Zr_1/2Ti_1/2)O₃‐0.1Pb(Zn_1/3Nb_2/3)O₃: (0.9PZT‐0.1PZN)). PZ‐PNN is depicted to illustrate an energy density of 70 kJ/m³ under the conditions of 0–106 MPa applied stress and 1–15 kV/cm electric field. On the other hand, a maximum energy density of 50 kJ/m³ is obtained for 0.9PZT‐0.1PZN under ambient conditions of 0–173 MPa compressive stress and 1 to 18 kV/cm electric field.     

Growth of thin film ferroelectric PZT,PHT, and antiferroelectric PHO from atomic layer deposition precursors

We present a conformal method of growing ferroelectric lead hafnate-titanate (PbHf_xTi_1−xO₃, PHT) and lead zirconate-titanate (PbZr_xTi_1−xO₃, PZT) using atomic layer deposition (ALD) precursors. The 4+ cation precursors consist of tetrakis dimethylamino titanium (TDMAT), tetrakis dimethylamino zirconium (TDMAZ) and tetrakis dimethyl amino hafnium (TDMAH) for Ti, Zr, and Hf, respectively. The Pb (2+) precursor was Lead bis(3-N,N-dimethyl-2-methyl-2-propanoxide) [Pb(DMAMP)₂]. PZT was limited to lead titanate (PTO)-rich compositions, where x <0.25 for PbZr_xTi_1−xO₃, and exhibited a remnant polarization of 26-27 µC/cm² with a coercive field between 150 and 170 kV/cm. The 3D-structure coating capability of PZT was demonstrated by deposition on micromachined trench sidewalls 45 µm deep. We fabricated Microelectromechanical systems (MEMS) cantilever arrays with PZT thin films grown using the present method and demonstrated piezoelectric actuation. Alternatively, PHT was deposited with Ti and Hf compositions within ±1 at.% of the morphotropic phase boundary (MPB). The PHT exhibited a remanent polarization of 7.0-8.7 µC/cm² with a coercive field between 84-100 kV/cm. We applied the same Pb and Hf precursors from the PHT process to grow antiferroelectric lead-hafnate (PHO), which showed the characteristic electric field-induced ferroelectric phase transition at approximately ±280 kV/cm and a maximum polarization of approximately ±32.8 µC/cm².     

Thermally stable energy storage properties in relaxor BNT-6BT-modified antiferroelectric PNZST ceramics

Relaxor ferroelectric 0.94Na_0.5Bi_0.5TiO₃-0.06BaTiO₃-modified antiferroelectric Pb_0.99Nb_0.02[(Zr_0.57Sn_0.43)_0.94Ti_0.06]_0.98O₃ ceramics, (1−x)PNZST-x(BNT-6BT), were prepared to acquire high energy storage and thermal stability properties. X-ray diffraction and element mapping revealed that a solid solution between PNZST and BNT-6BT occurs, and Ti cations enter the PNZST lattice, partly extruding Sn cations and leading to the formation of isolated SnO₂ particles at the grain boundaries and a 0-3 type composite structure. Such a composite structure helps to create deviatoric stress in the solid solution component. The BNT-6BT content significantly influences the energy storage capacity, and the x = 0.2 composition renders optimal performance. The room-temperature-recoverable energy density and energy efficiency are 2.23 J/cm³ and 78%, respectively, at 260 kV/cm. Both parameters vary less than 6% within a temperature range of 25°C and 125°C. The improved energy storage and temperature stability indicate that the ceramics can potentially be applied in pulse power capacitors and that this relaxor-modified antiferroelectric ceramic preparation method is a valuable reference for further optimizing the functional properties.     

Electric field-induced phase transition and energy storage performance of highly-textured PbZrO3 antiferroelectric films with a deposition temperature dependence

Thin PbZrO₃ (PZO) antiferroelectric films with (001)-preferred orientation were deposited on SrRuO₃/Ca₂Nb₃O₁₀-nanosheet/Si substrates using pulsed laser deposition. Variation of the deposition temperature was found to play a key role in the control of the microstructure and strongly influence the energy storage performance of the thin film. The critical phase switching field, where the aligned antiferroelectric (AFE) domains start to transform into the ferroelectric (FE) state, decreased with increasing temperature. On the other hand, the content of the FE phase in the AFE PZO thin films increased with increasing deposition temperature. A large recoverable energy-storage density of 16.8?J/cm³ and high energy-storage efficiency of 69.2% under an electric field of 1000?kV/cm were achieved in the films deposited at 525?°C. This performance was due to the high forward switching field and backward switching field values and the low difference between these two fields. Moreover, the PZO thin films showed great charge-discharge cycling life with fatigue-free performance up to 10¹⁰ cycles and good thermal stability from room temperature to 100?°C.     

PLZST antiferroelectric ceramics with promising energy storage and discharge performance for high power applications

Capacitors are widely used as energy storage elements in electric vehicles (EVs) and pulsed power. At present, it is still challenging to develop capacitor dielectrics with good energy storage and discharge performance. In this work, antiferroelectric (AFE) ceramics (Pb_0.94La_0.04)[(Zr_0.6Sn_0.4)_0.92Ti_0.08]O₃ with enhanced antiferroelectricity were fabricated by a rolling process. The obtained ceramics have a high recoverable energy density of 5.2 J/cm³ and an extremely high efficiency of 91.2% at 327 kV/cm. The ceramics have good energy storage and discharge performance in the temperature range from −40°C to 100°C due to the existence of AFE phase. An energy density of 3.7 J/cm³ can be released at 200 kV/cm in less than 500 ns and the discharge current keeps stable after 1000 charge-discharge cycles. By direct short experiment, a current density of 1657 A/cm², which is the highest result in recently developed AFE ceramics, and a power density of 228 MW/cm³ were achieved. The possibility of using AFEs at low temperature was confirmed. The excellent energy storage and discharge performance prove the great potential of the obtained ceramics in high energy and power density applications.     

Achieving high-energy storage performance of PbZro3-based thin films utilizing insulation interlayer and low-temperature annealing

PbZrO₃ (PZO)-based antiferroelectric thin films are of great interest due to their high-power density and fast charging and discharging capability. However, the problems of low breakdown strength and inferior energy storage density of PZO films have not been well solved. In this work, the insulating MgO as the blocking interlayer is inserted into PbZrO₃ films (abbreviated as P/M/P), which can inhibit the electric charge transfer and enhance the breakdown strength, as well as regulation of the polarization behavior. The results show that the maximal endurable electric field is significantly improved, and the double-hysteresis characteristic disappeared after introducing MgO blocking interlayer. The energy storage density of P/M/P films reaches 21.97 J/cm³ under 1700 kV/cm, accompanying an ultralow efficiency of 44.01% due to the severe polarization loss. Furthermore, low-temperature annealing is performed to suppress the polarization loss, and an energy storage density of 17.27 J/cm³ accompanying a high efficiency of 75.53% is obtained at 3100 kV/cm, still exhibiting good stability after 1 × 10⁷ fatigue cycles. This study demonstrates that combining the insulating interlayer and the low-temperature annealing endow the PZO-based films significantly improved energy storage properties, having great potential to be used in the dielectric capacitors.     

Tunable antiferroelectric ceramic polarization via regulating incommensurate phase and domain features

Due to the high demand for dielectric materials with high energy density, the energy storage performance of antiferroelectric ceramic capacitors has always gained much attention. Polarization intensity is a key factor that is closely related to the energy storage density. However, thus far, there has been a lack of research studies or successful methods to effectively modulate polarization intensity. The behavior of the polarization process is complex and contains domain nucleation, growth, and flip-flapping. Based on this finding, the introduction of Nb⁵⁺ at the B-site was designed to influence the three stages of antiferroelectric polarization by regulating the balance between the ferroelectric and antiferroelectric phases, and eventually realized regulation of the saturation polarization intensity in the (Pb_1-1.5xLa_x)(Zr_0.5Sn_0.43Ti_0.07)O₃ antiferroelectric ceramics. The saturation polarization intensity has increased from 25.56 to 42 μC/cm² with Nb⁵⁺ content increases from 0 to 4 mol% and the hysteresis was kept low, Pb_0.94La_0.04(Zr_0.65Sn_0.35)_0.975Nb_0.02O₃ is the optimal component with a high releasable energy density of 8.26 J/cm³ and an energy storage efficiency of 90.31%. This work provides an in-depth explanation of the microscopic mechanism of antiferroelectric ceramic polarization and presents a novel approach for the composition design of high-energy storage density antiferroelectric ceramics.     

PZT-nickel ferrite and PZT-cobalt ferrite comparative study: Structural,dielectric, ferroelectric and magnetic properties of composite ceramics

Comparative study of different PZT-based composite materials ((x)PbZr_0.52Ti_0.48O₃ + (1-x)CoFe₂O₄ and (x)PbZr_0.52Ti_0.48O₃ +(1-x)Ni_0.7Zn_0.3Fe₂O₄ (x = 0.8 and 0.9)) is presented in the frame of structural, dielectric, ferroelectric and magnetic properties. PZT and NZF/CF powders were synthesized by auto combustion technique. The composites were synthesized by mixing the appropriate amount of individual phases using conventional sintering. XRD data indicated the formation of well crystallized structure of PZT and NZF/CF, without the presence of undesirable phases. SEM micrographs revealed a uniform grain distribution of both, ferroelectric and ferromagnetic phases. Non-saturated hysteresis loops are evident in all samples due to the existence of non-ferroelectric ferrite phase. All the samples exhibit typical ferromagnetic hysteresis loop, indicating the presence of the order magnetic structure. Dielectric investigations revealed that ferrites are the main source of charge carriers, which must be of electronic origin. The activation energy of effective electrical resistivity is heavily influenced by the ferroelectric phase.     

Effects of phase transition on discharge properties of PLZST antiferroelectric ceramics

The effects of electric field‐induced phase transition on discharge properties of Pb_0.94La_0.04[(Zr_0.52Sn_0.48)_0.84Ti_0.16]O₃ antiferroelectric (AFE) ceramics were investigated. Due to the forward phase transition, high polarization and energy density are achieved. The backward phase transition results in nonlinear increase of current in underdamped circuit. The stored charge (14.2 μC under 40 kV/cm at 22°C) can be released completely in very short duration due to the low remanent polarization. With increasing temperature, the polarization and releasable energy decline. However, the current amplitude reaches maximum at 40°C, which is attributed to the backward phase transition. The maximum current and power density are as high as 143.8 A/cm² and 2.4 MW/cm³, which indicates the potential of the ceramics for pulsed capacitors.     

Relaxation behavior of PbZrO3-SrTiO3 thin film for enhancing energy storage performances

In recent years, antiferroelectric materials have attracted significant attention as energy storage materials in pulsed power systems. In this study, (1-x)PbZrO₃-xSrTiO₃ (PZO-STO) antiferroelectric films were prepared, and the effects of the STO content on the microstructure and energy storage performance of the thin films were investigated in detail. The results showed that when the PZO/STO ratio was near the morphotropic phase boundary, the long-range PZO-STO-ordered structure could be broken by the paraelectric nanograins generated at the grain boundary. The number of nanoparticles increased gradually with an increase in the STO content, thereby leading to the microstructure transformation of the thin films from antiferroelectric to relaxation ferroelectric. When the STO content was 20%, the as-prepared thin film had a maximum energy storage density of 15.26 J/cm³, which was 117.14% higher than that of the pure PZO thin film.     

High-performance antiferroelectric ceramics via multistage phase transition

Lead-based antiferroelectric (AFE) ceramics have attracted increasing interest in pulse power systems owing to their high-energy storage and power densities. However, the single AFE–ferroelectric (FE) phase transition in conventional AFE materials usually leads to premature polarization saturation and low breakdown strength, which are disadvantageous to energy storage performance. In this study, high energy storage performance was achieved in Pb_0.94−xLa_0.04Ca_x[Nb_0.02(Zr_0.99Ti_0.01)_0.975]O₃ (PLCNZT) AFE ceramics by constructing electric-field-induced multiple phase transitions. A maximum recoverable energy storage density of 12.15 J/cm³ and a high energy efficiency of 85.4% were obtained for the PLCNZT ceramic with x = 0.03 at 420 kV/cm. These excellent properties are attributed to the AFE–FE Ⅰ-FE Ⅱ multiple phase transitions induced by Ca²⁺ doping, which effectively enhances the breakdown strength. This result indicates that field-induced multiple phase transitions significantly improve the energy storage of AFE materials.     

Giant Thermal–Electrical Energy Harvesting Effect of Pb0.97La0.02(Zr0.75Sn0.18Ti0.07)O3 Antiferroelectric Thick Film

In this letter, 2‐μm Pb_0.97La_0.02(Zr_0.75Sn_0.18Ti_0.07)O₃ antiferroelectric thick film with tetragonal structure was prepared. The effects of operating electric field, temperature, and frequency on the thermal–electrical energy harvesting capacity of the film were studied by using the Olsen cycle. The results demonstrated that giant energy harvesting effect could be realized in the antiferroelectric thick film. The maximum harvestable energy density per cycle of the film was about 7.8 J/cm³ at 1 kHz, which was the largest reported value to date. The corresponding energy harvesting efficiency was 0.53%. Moreover, the film had a low leakage current density (about 7.3 × 10^?7 and 3.9 × 10^?5 A/cm² at 25 and 200°C, respectively), which was favorable for its application in the devices of the thermal–electrical energy harvesting.     

Enhancement of energy storage density in antiferroelectric PbZrO3 films via the incorporation of gold nanoparticles

In this work, antiferroelectric Au–PbZrO₃ (Au–PZO) nanocomposite thin films were prepared by chemical solution deposition (CSD), and the effects of Au concentration on the antiferroelectric properties and the recoverable energy density were investigated. The results showed that the optimal Au concentration in the Au–PZO nanocomposite thin films was about 1 mol% for structural and electric properties. In the Au–PZO nanocomposite thin films with 1 mol% Au, Au nanoparticles (NPs) were distributed uniformly in the perovskite PZO matrix. Moreover, the recoverable energy density was 10.8 J/cm³ at 600 kV/cm, which is 42% higher than that of the pure PZO films. The results demonstrate that adding an appropriate amount of noble metal NPs in antiferroelectric thin films is an effective method to improve the energy storage properties.