Antiferroelectric Thin Films Research Articles

Influence of Zr/Sn ratio on the Transverse Piezoelectric Coefficient in Lanthanum-Doped Lead Zirconate Titanate Stannate Thin Films

In this study, we report the effect of Zr/Sn ratio on the Antiferroelectric (AFE) → Ferroelectric (FE) phase transition and transverse piezoelectric characteristics on AFE thin films of compositions having the general formula Pb0.97La0.02(Zr1-x+ySnxTiy)O3, where y = 0.10 and 0.10 ≤ x ≤ 0.15 along the phase boundary in the ternary system Pb(Zr0.50Ti0.50)O3-Pb(Zr0.50Sn0.50)O3-PbZrO3. Thin films having a thickness of 2.0 µm were fabricated on platinised silicon substrates by sol–gel method. Data obtained from dielectric, ferroelectric and structural studies have been combined to explain the mechanism of AFE → FE switching.

Significantly improved energy storage properties and cycling stability in La-doped PbZrO3 antiferroelectric thin films by chemical pressure tailoring

In this work, Pb1−3x/2LaxZrO3 (x = 0–0.12) (PLZ-x) antiferroelectric thin films were fabricated on Pt(111)/TiO2/SiO2/Si substrates using chemical solution method. Smaller cations (La3+) and vacancies were introduced into A-sites of perovskite structure to construct chemical pressure. According to phenomenological theory, chemical pressure can increase the energy barrier between antiferroelectric (AFE) and ferroelectric (FE) phase, and enhance antiferroelectricity of the system. As a result, a large energy storage density (Wre) of 23.1 J cm−3 and high efficiency (η) of 73% were obtained in PLZ-0.10 films, while PLZ-0 films displayed lower Wre (15.1 J cm−3) and η (56%). More importantly, PLZ-0.10 films exhibited an excellent cycling stability with a variation of ˜2% after 1 × 108 cycles. The results demonstrate that heavily La-doped PbZrO3 films with high energy storage density, high efficiency and excellent cycling stability can be considered as potential candidates for energy storage applications.

Broadening of X-ray reflections and inhomogeneous strain distribution in PbZrO3/SrRuO3/SrTiO3 epitaxial heterostructures

Antiferroelectric thin film heterostructures are important in energy storage technology and have prospective applications in domain wall nanoelectronics. The improvement of functional properties of this kind of material is directly connected with the effect of epitaxial strain. Thus, the investigations of strain distribution in the antiferroelectic films volume are on demand. In this work we have studied the distribution of orientational domain states and the condition of near-interface layer in a set of PbZrO3 films with different thickness grown on SrRuO3/SrTiO3 substrate. The analysis of X-ray diffraction curves shows that only the relatively narrow near-interface part of PbZrO3 film experiences significant strain along the normal to the surface, which decays very quickly on moving away from the interface. The out-of-plane strain profiles are strongly similar in films of different thickness above d=50 nm. The inhomogeneous out-of-plane strain is surprisingly of compressive character, which we attribute to the effects of hydrostatic-like compression associated with the presence of edge dislocations. In the films of higher thickness, we observe unusual broadening of the Bragg reflections, which is also tentatively associated with relaxation through the formation of dislocations.

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

AbstractIn 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.

Phase transition and energy storage behavior of antiferroelectric PLZT thin films epitaxially deposited on SRO buffered STO single crystal substrates

Abstract(Pb0.98, La0.02)(Zr0.95, Ti0.05)O3 (PLZT) thin films of 300 nm thickness were epitaxially deposited on (100), (110), and (111) SrTiO3 single crystal substrates by pulsed laser deposition. X‐ray diffraction line and reciprocal space mapping scans were used to determine the crystal structure. Tetragonal ((001) PLZT) and monoclinic MA ((011) and (111) PLZT) structures were found, which influenced the stored energy density. Electric field‐induced antiferroelectric to ferroelectric (AFE→FE) phase transitions were found to have a large reversible energy density of up to 30 J/cm3. With increasing temperature, an AFE to relaxor ferroelectric (AFE→RFE) transition was found. The RFE phase exhibited lower energy loss, and an improved energy storage efficiency. The results are discussed from the perspective of crystal structure, dielectric phase transitions, and energy storage characteristics. Besides, unipolar drive was also performed, providing notably higher energy storage efficiency values due to low energy losses.

Giant negative electrocaloric effect in antiferroelectric PbZrO3 thin films in an ultra-low temperature range

Antiferroelectric thin films have demonstrated an excellent negative electrocaloric effect, and are potential candidates for future refrigeration applications.

Intermediate phase with orthorhombic symmetry displacement patterns in epitaxial PbZrO3 thin films at high temperatures

Antiferroelectric PbZrO3 epitaxial thin film with thickness of 50 nm grown on the SrTiO3 substrate with SrRuO3 buffer layer was studied by Grazing incidence X-ray diffraction in a wide range of temperatures. Apart from the superstructure reflections characteristic for the antiferroelectric phase, we identify the reflections with pseudocubic coordinates of the form (H + 0.5, K + 0.5, L). This indicates the presence of structures having orthorhombic symmetry as an effect of anti-phase Pb atoms displacements, which are apparently similar to the ones previously proposed for the rhombohedral high-temperature phase in PbZrxTi1-xO3. For these structures only the domain orientations with displacements parallel to the surface are observed in contrast to the antiferroelectric domains where the parallel to surface Pb displacements are absent. The antiferroelectric phase coexists with the one characterized by (H + 0.5, K + 0.5, L) reflections in a broad temperature range with the maximal amount of the latter being present at T = 150 °C.

Endurance properties of silicon-doped hafnium oxide ferroelectric and antiferroelectric-like thin films: A comparative study and prediction

Hafnium oxide based ferroelectric (FE) and antiferroelectric (AFE) thin films show great potentials in memory and energy related applications, while their successes in commercially available devices depend strongly on detailed characterization and deep understanding of the endurance properties of the materials. In this work, the bipolar field cycling behavior has been investigated in detail for FE and AFE-like Si-doped HfO2 films. Their apparent differences in fatigue and breakdown resistance are interpreted by the modified switching-induced charge-injection model. Referring to the first-order phase transition theory, we summarize and predict the evolution of polarization switching characteristic for FE, AFE-like and AFE Si-doped HfO2 thin films stressed with bipolar field cycling. Additionally, several approaches are suggested to improve the endurance properties of ferroelectric HfO2-based thin films in terms of fabrication process and material design.

Thermal strain induced large electrocaloric effect of relaxor thin film on LaNiO3/Pt composite electrode with the coexistence of nanoscale antiferroelectric and ferroelectric phases in a broad temperature range

Ferroelectric/antiferroelectric thin/thick films with large electrocaloric (EC) effect in a broad operational temperature range are very attractive in solid-state cooling devices. We demonstrated that a large positive electrocaloric (EC) effect (maximum ΔT ~ 20.7 K) in a broad temperature range (~ 110 K) was realized in Pb0.97La0.02(Zr0.65Sn0.3Ti0.05)O3 (PLZST) relaxor antiferroelectric (AFE) thin film prepared using a sol-gel method. The large positive EC effect may be ascribed to the in-plane residual thermal tensile stress during the layer-by-layer annealing process, and the high-quality film structure owing to the utilization of the LaNiO3/Pt composite bottom electrode. The broad EC temperature range may be ascribed to the great dielectric relaxor dispersion around the dielectric peak because of the coexistence of nanoscale multiple FE and AFE phases. Moreover, a large pyroelectric energy density (6.10 Jcm−3) was harvested by using an Olsen cycle, which is much larger than those (usually less than 10− Jcm−3) obtained by using direct thermal-electrical, Stirling and Carnot cycles, etc. These breakthroughs enable the PLZST thin film an attractive multifunctional material for applications in modern solid-state cooling and energy harvesting.

Large energy storage density, low energy loss and highly stable (Pb0.97La0.02)(Zr0.66Sn0.23Ti0.11)O3 antiferroelectric thin-film capacitors

In this work, high performance (Pb0.97La0.02)(Zr0.66Sn0.23Ti0.11)O3 polycrystalline antiferroelectric thin-film was successfully fabricated on (La0.7Sr0.3)MnO3/Al2O3(0001) substrate via a cost-effectively chemical solution method. A large recoverable energy storage density (Wre) of 46.3 J/cm3 and high efficiency (η) of 84% were realized simultaneously under an electric field of 4 MV/cm by taking full advantage of the linear dielectric response after the electric field induced antiferroelectric-ferroelectric transition. Moreover, the PLZST thin-film displayed high temperature stability. With increasing temperature from 300 K to 380 K, the Wre decreased only 1.3%. The film also exhibited good fatigue endurance up to 1 × 105 cycling under an electric field of 2.2 MV/cm. Our work underlines the importance of the interface quality between the film and the substrate and the important role of linear dielectric answer after saturation in the improvement of the energy storage density and efficiency of antiferroelectric materials.

Flexible high energy density capacitors using La-doped PbZrO3 anti-ferroelectric thin films

Flexible high energy density capacitors were fabricated by depositing 6 mol. % La-doped anti-ferroelectric PbZrO3 thin films using chemical solution deposition on ultra-thin metal foil substrates. The integration of a LaNiO3 buffer layer on the flexible austenitic metal foil substrate resulted in substantial improvements in microstructure uniformity and density of the La-doped PbZrO3 thin film capacitors. The recoverable energy density and the energy loss of the flexible thin film capacitors were 15.2 ± 0.2 J/cm3 and 4.8 ± 0.2 J/cm3 at 1 MV/cm, respectively. The La-doped PbZrO3 flexible thin film capacitors showed no noticeable degradation in ferroelectric hysteresis behavior and the energy storage density even after 1000 bending cycles.

Combining inverse and conventional pyroelectricity in antiferroelectric thin films for energy conversion

Resonant charging between inverted regions of pyroelectric coefficient in antiferroelectric thin films enables energy conversion schemes analogous to piston engines.

Silicon-doped hafnium oxide anti-ferroelectric thin films for energy storage

Motivated by the development of ultracompact electronic devices as miniaturized energy autonomous systems, great research efforts have been expended in recent years to develop various types of nano-structural energy storage components. The electrostatic capacitors characterized by high power density are competitive; however, their implementation in practical devices is limited by the low intrinsic energy storage density (ESD) of linear dielectrics like Al2O3. In this work, a detailed experimental investigation of energy storage properties is presented for 10 nm thick silicon-doped hafnium oxide anti-ferroelectric thin films. Owing to high field induced polarization and slim double hysteresis, an extremely large ESD value of 61.2 J/cm3 is achieved at 4.5 MV/cm with a high efficiency of ∼65%. In addition, the ESD and the efficiency exhibit robust thermal stability in 210–400 K temperature range and an excellent endurance up to 109 times of charge/discharge cycling at a very high electric field of 4.0 MV/cm. The superior energy storage performance together with mature technology of integration into 3-D arrays suggests great promise for this recently discovered anti-ferroelectric material to replace the currently adopted Al2O3 in fabrication of nano-structural supercapacitors.

Electrocaloric effect in PbZrO3 thin films with antiferroelectric-ferroelectric phase competition

Electrocaloric effect in antiferroelectric PbZrO3 thin films that undergo antiferroelectric-ferroelectric phase transition upon cooling down is investigated using atomistic first-principles-based simulations. It is found that such a phase transition is associated with a large positive electrocaloric response that can reach 13K under electric field of 500kV/cm. High tunability of the phase transition by the electric field leads to a wide range of temperatures associated with strong electrocaloric response. Epitaxial strain was found to provide further tunability to the electrocaloric properties. Large intrinsic electrocaloric effect at the antiferroelectric-ferroelectric phase transition and its high tunability by the electric field offer promising technological applications.

Energy-storage performance and pyroelectric energy harvesting effect of PNZST antiferroelectric thin films

In this work, (111)-oriented (Pb0.99Nb0.02)(Zr, Sn, Ti)0.98O3 (PNZST) antiferroelectric thin films, which located in the tetragonal phase region (PNZSTT) and the orthorhombic phase region (PNZSTO), respectively, were successfully fabricated on platinum-buffered silicon substrates by radio-frequency magnetron sputtering technique. The microstructure, dielectric properties, electric field induced phase transition, associated with the energy-storage performance and pyroelectric energy harvesting behavior (by Olsen cycle) were studied systemically. The PNZSTT thin film showed a diffused field-induced antiferroelectric–ferroelectric (AFE–FE) phase switching with a slim double hysteresis loop, while the PNZSTO film demonstrated an AFE–FE phase switching with a square double hysteresis loop. A maximum recoverable energy-storage density of 16.4 and 12.4 J/cm3 were obtained in the PNZSTT and PNZSTO film, respectively. Moreover, a huge harvested energy density per cycle of W = 7.35 and 5.35 J/cm3 was also predicted in the PNZSTT and PNZSTO film at 1 kHz, respectively. The good energy-storage performance and giant thermal-electrical energy harvesting effect of the PNZST antiferroelectric thin films maybe make a great impact on the modern energy-storage technology and the thermal-electrical energy harvesting applications.

Antiferroelectric polarization switching and dynamic scaling of energy storage: A Monte Carlo simulation

The polarization-electric field hysteresis loops and the dynamics of polarization switching in a two-dimensional antiferroelectric (AFE) lattice submitted to a time-oscillating electric field E(t) of frequency f and amplitude E0, is investigated using Monte Carlo simulation based on the Landau–Devonshire phenomenological theory on antiferroelectrics. It is revealed that the AFE double-loop hysteresis area A, i.e., the energy loss in one cycle of polarization switching, exhibits the single-peak frequency dispersion A(f), suggesting the unique characteristic time for polarization switching, which is independent of E0 as long as E0 is larger than the quasi-static coercive field for the antiferroelectric–ferroelectric transitions. However, the dependence of recoverable stored energy W on amplitude E0 seems to be complicated depending on temperature T and frequency f. A dynamic scaling behavior of the energy loss dispersion A(f) over a wide range of E0 is obtained, confirming the unique characteristic time for polarization switching of an AFE lattice. The present simulation may shed light on the dynamics of energy storage and release in AFE thin films.

Emergence of ferroelectricity in antiferroelectric nanostructures

First-principles-based finite-temperature simulations are used to predict the emergence of ferroelectricity in antiferroelectric nanostructures made of PbZrO3. The phenomenon is expected to occur in antiferroelectric nanodots, nanowires, and thin films with good surface charge compensation and can be explained by the recently proposed surface effect []. Our computations provide a microscopic insight into the equilibrium phases, phase competition, and electrical properties of PbZrO3 nanostructures. The dependence of these properties on the electrical boundary conditions and nanostructure size is investigated.

Thickness-dependent dielectric and energy storage properties of (Pb0.96La0.04)(Zr0.98Ti0.02)O3 antiferroelectric thin films

A series of dense and uniform (Pb0.96La0.04)(Zr0.98Ti0.02)O3 (PLZT) thin films with different thicknesses have been deposited on (La2/3Sr1/3)MnO3/SrTiO3 substrates by a modified chemical solution deposition method. Structural and electrical studies indicate that PLZT thin films show single phase composition and typical antiferroelectric (AFE) characteristics. By increasing the film thickness, the dielectric loss of PLZT thin films is reduced and the hysteresis loops are tailored. The energy storage efficiency increases from 56.8% to 74.1%, while a high energy density of ∼20 J/cm3 is maintained under an electric field of 1200 kV/cm. Additionally, the operating frequencies also have distinct influence on the hysteresis loop shape and the energy storage properties, indicating that energy storage performance of AFE thin films can be enhanced by tuning both film thickness and operating frequencies.

A giant negative electrocaloric effect in Eu-doped PbZrO3 thin films

A negative electrocaloric effect (ECE) in 4 mol% Eu-doped PbZrO3 antiferroelectric (AFE) thin films prepared by using a sol–gel method is investigated via indirect measurements.

Critical Thickness for Antiferroelectricity in PbZrO3.

Ferroelectrics and antiferroelectrics appear to have just the opposite behavior upon scaling down. Below a critical thickness of just a few nanometers the ferroelectric phase breaks into nanodomains that mimic electric properties of antiferroelectrics very closely. On the other hand, antiferroelectric thin films were found to transition from the antiferroelectric behavior to a ferroelectric one under certain growth conditions. At present, the origin of such a transition is controversial. Here, we use accurate first-principles-based finite-temperature simulations to predict the existence of a critical thickness for antiferroelectricity in the most celebrated antiferroelectric, PbZrO3. The origin of this effect is traced to the intrinsic surface contribution that has been previously overlooked. The existence of a critical thickness below which the antiferroelectric phase is replaced with a ferroelectric one not only complements the discovery of a critical thickness for ferroelectricity, but also suggests that ferroelectricity and antiferroelectricity are just two opposite manifestations of the same phenomenon: the material's tendency to develop a long-range order. Nanoscaling offers the opportunity to manipulate this order.