O3 Antiferroelectric Thick Films Research Articles

Induced slim ferroelectric hysteresis loops and enhanced energy-storage properties of Mn-doped (Pb0·93La0.07)(Zr0·82Ti0.18)O3 anti-ferroelectric thick films by aerosol deposition

In this study, the high ferroelectric hysteresis loss of (Pb0·93La0.07)(Zr0·82Ti0.18)O3 (PLZT 7/82/18) antiferroelectric (AFE) ceramics was reduced by employing a combinatorial approach of Mn acceptor doping followed by thick film fabrication via an aerosol deposition (AD) process. The grains of the as-deposited PLZT 7/82/18 AFE AD thick films were grown by thermal annealing at 550 °C to enhance their electrical properties. Investigation of the electrical properties revealed that Mn-doping results in improved dielectric and ferroelectric properties, increased dielectric breakdown strength (DBS), and energy-storage properties. The Mn-doped PLZT AFE AD films possess a frequency-independent high dielectric constant (εr ≈ 660) with low dielectric loss (tan δ ≈ 0.0146), making them suitable candidates for storage capacitor applications. The bipolar and unipolar polarization vs. electric field (P-E) hysteresis loops of PLZT 7/82/18 AFE AD thick films were found to be slimmer than those of their bulk form (double hysteresis) with significantly reduced ferroelectric hysteresis loss, which is attributed to the AD-induced mixed grain structure. The Mn-doped PLZT 7/82/18 AFE AD thick films exhibited a low remnant polarization (Pr ≈ 9.22 μC/cm2) at a high applied electric field (~2750 kV/cm). The energy-storage density and energy efficiency of the Mn-doped PLZT AFE AD thick films were calculated from unipolar P-E hysteresis loops and found to be ~38.33 J/cm3 and ~74%, respectively.

Energy storage and thermodynamics of PNZST thick films with coexisting antiferroelectric and ferroelectric phases

AbstractPb0.99Nb0.02(Zr0.85Sn0.13Ti0.02)O3 (PNZST) antiferroelectric (AFE) thick films are successfully deposited on silicon‐based Pt and LaNiO3 electrodes by a sol‐gel method. The coexistence of ferroelectric (FE) and AFE phases are revealed in PNZST films by XRD, electric‐induced hysteresis loops, dielectric, and leakage current properties. Comparing with PNZST/Pt film, larger recoverable energy density and efficiency are obtained in PNZST/LaNiO3 film due to the lower FE phase proportion. It is analyzed and demonstrated by a thermodynamic model of AFE and FE coexistence system. In addition, the fatigue behaviors of both AFE films are also affected by the proportion of the coexisting FE phase. PNZST/LaNiO3 film exhibits good fatigue resistance on energy storage even after 1010 switching cycles, which is attractive to pulsed power applications.

The coexisting negative and positive electrocaloric effect in (Pb0.97La0.02)(Zr, Sn, Ti)O3 antiferroelectric thick films optimized via phase transition procedure

Pb0.97La0.02(Zr1 − x−ySnxTiy)O3 (PLZST, x = 0.37, 0.25 and 0.05; corresponding y = 0.08, 0.05 and 0.03) anti-ferroelectric (AFE) thick films with different phase structure were prepared by a sol–gel method. It is found that the PLZST thick films possess coexistence of the negative and positive electrocaloric effect (ECE). The negative ECE is caused by the transition from AFE to ferroelectric phase (FE) and enhanced as the AFE–FE switching field increases. The PLZST thick films for x = 0.37, 0.25 and 0.05 have the maximum negative temperature change ΔT of − 1.0, − 2.0 and − 4.1 °C near room temperature, respectively. Moreover, the maximum positive temperature change ΔT is 1.0, 5.4 and 6.1 °C near the Curie temperature in PLZST thick films (x = 0.37, 0.25 and 0.05), respectively, which is associated with the transition from induced FE to paraelectric state. The results indicate that the coexisting negative and positive ECE could be optimized by properly controlling the phase switching properties of AFEs.

Orientation-dependent energy-storage performance and electrocaloric effect in PLZST antiferroelectric thick films

The enhancement of the energy-storage performance and electrocaloric effect (ECE) was achieved via orientation control. The 1.5-μm-(Pb0.97La0.02)(Zr0.73Sn0.22Ti0.05)O3 (PLZST) antiferroelectric (AFE) thick films with (111), (110), and (100) crystallographic orientations were successfully prepared via a sol-gel method. It was found that both the enhanced energy-storage density of 13.5J/cm3 at 900kV/cm and the corresponding temperature reduction of ΔT=28.1°C at room temperature were obtained in the PLZST thick film with (111) orientation due to a high polarization. Moreover, these films with different orientations display a small leakage current density at the room temperature. These results suggest that both energy-storage properties and cooling performance in AFEs could be optimized by the proper orientation control.

High‐Energy Storage Performance in (Pb0.98La0.02)(Zr0.45Sn0.55)0.995O3 AFE Thick Films Fabricated via a Rolling Process

(Pb0.98La0.02)(Zr0.45Sn0.55)0.995O3 antiferroelectric (AFE) thick films with a thickness of about 85 μm were successfully fabricated via a rolling process using an improved sintering method, and all specimens showed high‐energy‐storage performance. The X‐ray diffraction, SEM pictures, and hysteresis loops confirmed that the sintering temperature had an important influence on the microstructures, dielectric properties and energy storage performance of AFE thick films. The grain size and the storage efficiency increased with the increasing sintering temperature, the energy storage performance was enlarged by the rolling process. As a result, a maximum recoverable energy density of 7.09 J/cm3 with an efficiency of 88% was achieved at room temperature, together with stable energy‐storage behavior, which was almost three times higher than that (2.43 J/cm3) of the bulk ceramics counterparts. The results demonstrated that the improved method was an effective way to improve the breakdown strength and energy storage performance of AFE thick films, and (Pb0.98La0.02)(Zr0.45Sn0.55)0.995O3 AFE thick films were a promising material for high‐power energy storage.

Electrocaloric effect and energy-storage performance in grain-size-engineered PBLZT antiferroelectric thick films

The effects of grain size on dielectric properties, energy-storage performance and electrocaloric effect (ECE) of Pb0.85Ba0.05La0.10(Zr0.90Ti0.10)O3 (PBLZT) antiferroelectric thick films were systematically studied. As the grain size was increased, dielectric constant of the thick films was increased, while their critical breakdown field was decreased. A giant reversible adiabatic temperature change of ∆T = 19.9 °C at room temperature was achieved in the PBLZT AFE thick film with a grain size of 0.59 µm. However, a huge recoverable energy-storage density of 33.6 J/cm3 and a high efficiency of 73 % were observed in the film with the smallest grain size of 0.19 µm at its breakdown field, because of its excellent electric field endurance. In addition, all the samples had a low leakage current density of below 10−6 A/cm2 at room temperature. These results indicated that our PBLZT AFE thick films could be a promising candidate for applications in high energy-storage density capacitors and solid-cooling devices by properly controlling their grain size.

Energy storage and polarization switching kinetics of (001)-oriented Pb0.97La0.02(Zr0.95Ti0.05)O3 antiferroelectric thick films

For antiferroelectric (AFE) energy storage, the stability of energy storage density and conversion efficiency against wide temperature (T) range and broad frequency (f) band is highly preferred. In this work, we investigate the energy storage and associated kinetics of polarization switching in (001)-textured AFE Pb0.97La0.02(Zr0.95Ti0.05)O3 (PLZT 2/95/5) thick films prepared by sol-gel method. A recoverable energy storage density (Wre) of ∼26.8 J/cm3 and an energy conversion efficiency (η) as high as ∼62.5% have been obtained under an electric field of 1.85 MV/cm and room temperature. Both the Wre and η are only weakly T-dependent up to 280 °C and weakly f-dependent ranging from 20 Hz to 10 kHz. The high frequency stability originates from the rapid polarization switching as identified by the nucleation-limited-switching theory, suggesting a characteristic switching time as short as ∼3 ns, favorable for applications in pulse energy storage.

Out-of-plane actuation of silicon micro-cantilever based on (Pb, La) (Zr, Ti)O3 antiferroelectric thick films

With micro-machining technologies, the micro-cantilevers of Si-based antiferroelectric (Pb, La) (Zr, Ti)O3 thick films were fabricated, and five sizes of cantilevers were completed in one chip. Out-of-plane motion of the cantilever structure was described with the out-of-plane actuation method. Under the square wave excited by the voltage of 42 ± 2 V, the micro-cantilevers presented the good performance, such as high vibration velocity of 0.93 m/s and big cantilever tip displacement of 31 μm due to the electrical field induced phase transition in the thick film. The drive voltage as the phase-transition voltage was applied to the antiferroelectric material layers for the out-of-plane motions measured by Micro System Analyzer (MSA-400), and hence the 1st-order resonance frequency of the cantilevers was 40.08 kHz. These results reveal that the antiferroelectric thick films (Pb, La) (Zr, Ti)O3 are of characteristics of large electrostrictive strain and show the potential and board application for the micro-devices with those films in micro-actuators and high-speed digital switches.

Enhanced energy-storage performance and electrocaloric effect in compositionally graded Pb(1−3x/2)LaxZr0.85Ti0.15O3 antiferroelectric thick films

The compositionally graded multilayer Pb(1−3x/2)LaxZr0.85Ti0.15O3 (PLZT) antiferroelectric (AFE) thick films were deposited on LaNiO3/Si (100) substrates by using a sol–gel method. The effect of gradient sequence on dielectric properties, energy-storage performance, and electrocaloric effect (ECE) was investigated in detail. It is found that the compositionally graded films exhibited a significant enhancement in dielectric properties, energy-storage performance and ECE, which was, in contrast to the single-composition PLZT film, contributed by the strain and the gradient of polarization near the interfaces between the adjacent layers. A recoverable energy-storage density of 44J/cm3 and efficiency of 71% was obtained in the up-graded PLZT AFE thick film at 1950kV/cm. A giant reversible adiabatic temperature change of ∆T=28°C at room temperature at 900kV/cm was also achieved in the up-graded film. Moreover, all the thick films displayed a small leakage current density below 10−6A/cm2 at room temperature. Thus, the compositionally graded PLZT AFE thick films with a large recoverable energy-storage density and a giant ECE could be a potential candidate for the applications in high energy-storage density capacitors and cooling devices.

Improved electrocaloric effect in (100)-oriented Pb0.97La0.02(Zr0.57Sn0.38Ti0.05)O3 antiferroelectric thick film by interface engineering

In this work, 1.5-μm Pb0.97La0.02(Zr0.57Sn0.38Ti0.05)O3 antiferroelectric thick films with and without a ZrO2 thin layer were deposited on LaNiO3(100)/Si(100) substrates. The effects of ZrO2 thin layer on the microstructure, electrical properties, and especial electrocaloric effect of the antiferroelectric films were studied in detail. Although the films both with and without ZrO2 buffer layer displayed (100)-preferred orientation, possessed dense and uniform surface microstructure, the ZrO2-buffered films have an enlarged grain size by 27%, compared with the thick films without the buffer layer. Accordingly, the dielectric constant and saturate polarization of this antiferroelectric thick films was improved by the insertion of ZrO2 thin layer, and simultaneously its leakage current was slightly reduced. As a result, a great improvement in cooling character caused by ferroelectric–antiferroelectric phase switching, was realized in the ZrO2-buffered films.

Phase Structure Tuned Electrocaloric Effect and Pyroelectric Energy Harvesting Performance of (Pb0.97La0.02)(Zr,Sn,Ti)O3 Antiferroelectric Thick Films

In the present work, (100)-oriented (Pb0.97La0.02)(Zr0.95-xSnxTi0.05)O3 antiferroelectric thick films with x = 0.08, 0.20, and 0.38 were successfully fabricated. These compositions are located in the orthorhombic phase region, the morphotropic phase boundary (MPB), and the tetragonal phase region, respectively. The effects of their phase structure on the electrocaloric effect and the pyroelectric energy harvesting behavior were investigated. A considerable temperature reduction of ΔT = 13, 33, and 27 °C, due to the ferroelectric–antiferroelectric phase transition, was obtained at 25 °C in these thick films for x = 0.08, 0.20, and 0.38, respectively. Moreover, a huge harvested energy density per cycle of W = 3.6, 6.8, and 4.0 J/cm3 was also realized under the experimental condition in the thick films with x = 0.08, 0.20, and 0.38, respectively. These results indicated that both the cooling performance and the pyroelectric energy harvesting in antiferroelectrics could be optimized by the proper phase structure control.

Composition-dependent dielectric and energy-storage properties of (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric thick films

1.8 -μm-(Pb0.97La0.02)(Zr0.95−xSnxTi0.05)O3 antiferroelectric thick films with orthorhombic (x = 0.05 and 0.25) and tetragonal (x = 0.40) structure were deposited on platinum-buffered silicon substrates by using a chemical solution way. All the films had a uniform microstructure with pure perovskite phase. With increasing x value, dielectric constant and critical electric breakdown field of the thick films were gradually increased, while their saturated polarizations were decreased. As a result, their maximum recoverable energy-storage density was increased for the thick films with larger x values. A huge recoverable energy-storage density of 56 J/cm3 was obtained in antiferroelectric thick films with x = 0.40. Moreover, a good temperature-dependent stability of the energy storage was obtained in the all films from 20 to 120 °C.

Preparation and energy-storage performance of PLZT antiferroelectric thick films via sol–gel method

In this work, sol–gel-derived Pb0.97La0.02(Zr0.97Ti0.03)O3(PLZT 2/97/3) antiferroelectric (AFE) thick films were fabricated on LaNiO3-bottom electrodes through a two-step heat-treatment process. The effects of the heat-treatment process on the crystalline structure and the energy-storage performance of the AFE films were investigated in detail. While all the PLZT 2/97/3films crystallized into a pure perovskite phase, the film pyrolyzed at 600 °C shows a relatively more homogeneous surface morphology. As a result, the film pyrolyzed at 600 °C possesses the highest energy-storage efficiency of 64.4%. However, the film pyrolyzed at a lower temperature exhibits a larger energy storage density because of its large saturated polarization.The maximum energy storage density of 20.1 J/cm3was obtained at 1158 kV/cm for the films pyrolyzed at 550 °C.

Microstructure and energy-storage performance of PbO–B2O3–SiO2–ZnO glass added (Pb0.97La0.02)(Zr0.97Ti0.03)O3 antiferroelectric thick films

In this paper, Pb0.97La0.02(Zr0.97Ti0.03)O3 (PLZT 2/97/3) antiferroelectric (AFE) thick films with 0–5wt.% PbO–B2O3–SiO2–ZnO glass addition were successfully fabricated on alumina substrates via a screen printing method. The effects of the added glass on the microstructure, the dielectric properties, and the energy-storage performance of the PLZT 2/97/3 AFE thick films were investigated in detail. The results showed that the proper addition of glass powders was favor to form a denser microstructure with a pure perovsike phase. As a result, the dielectric properties and the energy-storage performance of AFE thick films were greatly improved by the addition of glass. The maximum recoverable energy-storage density of 3.1J/cm3 was obtained in 3-wt.% glass-added AFE thick films.

Fabrication and energy-storage performance of (Pb,La)(Zr,Ti)O3 antiferroelectric thick films derived from polyvinylpyrrolidone-modified chemical solution

In this work, Pb0.97La0.02(Zr0.98Ti0.02)O3 (PLZT 2/98/2) antiferroelectric (AFE) thick films were successfully deposited on LaNiO3/Si(100) substrates by polyvinylpyrrolidone (PVP)-modified chemical solution. Each wet layer was first dried at 300 °C and then pyrolyzed at higher temperature B of 600, 650, or 700 °C, respectively. The effects of the pyrolyzed temperature B on the microstructure and the energy-storage performance of the AFE films were investigated in detail. As the increasing of the pyrolyzed temperature, the crystallized PLZT 2/98/2 films displayed a more uniform and dense surface microstructure. As a result, the dielectric properties, AFE characterization, and energy-storage performance were remarkably improved for the AFE thick films pyrolyzed at higher temperature. The maximum energy-storage density of 58.1 J/cm3 and the corresponding energy-storage efficiency of 37.3% were obtained in the PLZT 2/98/2 films pyrolyzed at 700 °C for every layer.

Direct current electric field adjustable phase transformation behavior in (Pb,La)(Zr,Ti)O3 antiferroelectric thick films

(Pb,La)(Zr,Ti)O3 antiferroelectric 1.4 μm-thick films have been prepared on Pt (111)/Ti/SiO2/Si(100) substrates by sol–gel process. The structures and dielectric properties of the antiferroelectric thick films were investigated. The films displayed pure perovskite structure with (100)-preferred orientation. The surface of the films was smooth, compact and uniform. The antiferroelectric (AFE) characterization have been demonstrated by P (polarization)-E (electric field) and C(capacitance)-V (DC bias) curves. The AFE–ferroelectric (FE) and FE-to-paraelectric (PE) phase transition were also investigated as coupling functions of temperature and direct current electric field. With the applied field increased, the temperature of AFE-to-FE phase transition decreased and the FE-to-PE phase shifted to high temperature. The AFE-to-FE phase transition was adjustable by direct current electric field. (Pb,La) (Zr,Ti) O3 antiferroelectric films have broad application prospects in microelectromechanical systems because of the phase transition.

Electric-field-induced antiferroelectric to ferroelectric and ferroelectric to paraelectric phase transition at various temperatures in (Pb, La)(Zr, Ti)O3 antiferroelectric thick films

(Pb, La)(Zr, Ti)O3 antiferroelectric thick films with (100)-preferred orientation were fabricated on Pt(111)/Ti/SiO2/Si(100) substrates via a sol–gel method. The electric-field-induced antiferroelectric (AFE) to ferroelectric (FE) phase transition characteristics were studied by C (capacitance)–E (electric field) measurements at different temperature. The films were in AFE state under 0 kV/cm below 122 °C, and the switching field values decreased, with increasing temperature. The films were in FE state between 122 and 135 °C, and when the temperature above 135 °C, the films were in PE state. The temperature-dependent dielectric parameters were deconvoluted using a Gaussian fit multi-peaks showed that two typical phase transitions were discovered. The first peak is the AFE-to-FE phase transition and the second peak is the FE-to-PE phase transition which has been verified by C–E tests.

Structures and Dielectric Properties of (Pb, La)(Zr, Ti)O<sub>3</sub> Antiferroelectric Thick Films Prepared by Different Sintering Procedures

(Pb,La)(Zr,Ti)O3antiferroelectric thick films were prepared on Pt (111)/ Ti/SiO2/Si (100) substrates by a sol-gel process. The effects of single annealing and multistep annealing on the structures and electric properties of the films were investigated. The crystal orientation and structure of the antiferroelectric thick films were studied. The thick films by multistep annealing have higher (100)-preferred orientation than them by single annealing. The surface of the films was more smooth, compact and uniform by single annealing. The antiferroelectric nature of the (Pb,La)(Zr,Ti)O3antiferroelectric thick films by various sintering procedures was demonstrated by P(polarization)-E(electric field) and C(capactitance)-E(electric field). The temperature dependent of the dielectric constant and loss was measured under the frequency 1, 10, and 100 kHz and comparing with traditional signal annealing, the films have phase transition from antiferroelectric state to paraelectric state by multistep annealing.

Phase Transition Characterization Dependent on Temperature and DC Electric Field for (Pb, La) (Zr, Ti)O<sub>3</sub> Antiferroelectric Thick Films

Pb0.97La0.02(Zr0.95Ti0.05)O3 antiferroelectric thick films were prepared on platinized silicon substrates by sol–gel methods. Films showed polycrystalline perovskite structure with a strong (100) preferred orientation. The antiferroelectric nature of the films was confirmed by the double hysteresis behaviors versus applied field. The temperature dependence of dielectric constant and loss displayed the Curie temperature was 225oC.The current caused by the polarization and depolarization of polar was detected at coupling application of electric field and temperature. The phase transition characterization could be effectively adjusted by electric field and temperature.

Preparation and dielectric properties of highly preferred-(100) orientation (Pb, La)(Zr, Ti)O3 antiferroelectric thick films by sol–gel processing

Pb0.97La0.02Zr0.95Ti0.05O3 (PLZT) antiferroelectric thick films of highly preferred-(100) orientation with different thickness were successfully deposited on Pt(111)/Ti/SiO2/Si(100) substrates depending on the sol–gel process technique. The effects of the PLZT thick films in the preparation and electric properties are investigated. The films show polycrystalline perovskite structure with a (100) preferred orientation by X-ray diffractometer analyses. The antiferroelectric nature of the thick films is demonstrated by P (polarization)–E (electric field). The temperature dependence of the dielectric constant and dielectric loss displays the similar behavior in both cases at 100 kHz while the values of polarization characteristic are decreased with the increase of the film thickness. The phase switching current are studied as a function of a gradually change dc electric field and the voltage dependent current density of the most highly (100)-oriented PLZT film is 1.49 × 10−8 A/cm2 over electric field range from 0 to ±261 kV/cm. The film at 2,498 nm exhibits excellent dielectric properties and highly preferred-(100) orientation.