Ferroelectric Characteristics Research Articles

Ferroelectric Order in the Chiral Coordination Polymers [Ln2(L*)2(ox)2(H2O)2] with Ln=Gd3+ or Dy3+, L*=((S, S)‐1,3‐bis(1‐Carboxylethyl)imidazolium and Ox=Oxalate.

AbstractWe evidence the ferroelectricity of two isostructural magnetic coordination networks obtained from a chiral imidazolium dicarboxylate salt ((S, S)‐1,3‐bis(1‐carboxylethyl)imidazolium or [HL*]) and Gd3+ or Dy3+ ions in presence of oxalic acid (H2ox). The two compounds exhibit a chiral structure P1 and ferroelectric properties. The crystallographic study shows that the Dy based‐compound is isostructural to the Gd analog. The non‐centrosymmetry of the two samples was further checked by means of nonlinear optical spectroscopy. The room temperature ferroelectric character of the compounds has been investigated through by an original method, derived from that used for thin films, made possible by preparing the sample as thin slices of resin containing inclusions of the coordination compounds.

Evidence for reversible oxygen ion movement during electrical pulsing: enabler of emerging ferroelectricity in binary oxides

Ferroelectric HfO2-based materials and devices show promising potential for applications in information technology but face challenges with inadequate electrostatic control, degraded reliability, and serious variation in effective oxide thickness scaling. We demonstrate a novel interface-type switching strategy to realize ferroelectric characteristics in atomic-scale amorphous binary oxide films, which are formed in oxygen-deficient conditions by atomic layer deposition at low temperatures. This approach can avoid the shortcomings of reliability degradation and gate leakage increment in scaling polycrystalline doped HfO2-based films. Using theoretical modeling and experimental characterization, we show the following. (1) Emerging ferroelectricity exists in ultrathin oxide systems as a result of microscopic ion migration during the switching process. (2) These ferroelectric binary oxide films are governed by an interface-limited switching mechanism, which can be attributed to oxygen vacancy migration and surface defects related to electron (de)trapping. (3) Transistors featuring ultrathin amorphous dielectrics, used for non-volatile memory applications with an operating voltage reduced to ±1 V, have also been experimentally demonstrated. These findings suggest that this strategy is a promising approach to realizing next-generation complementary metal-oxide semiconductors with scalable ferroelectric materials.

Symmetry Engineering of Epitaxial Hf0.5Zr0.5O2 Ultrathin Films.

Robust ferroelectricity in HfO2-based ultrathin films has the potential to revolutionize nonvolatile memory applications in nanoscale electronic devices because of their compatibility with the existing Si technology. However, to fully exploit the potential of ferroelectric HfO2-based thin films, it is crucial to develop strategies for the controlled stabilization of various HfO2-based polymorphs in nanoscale heterostructures. This study demonstrates how substrate-orientation-induced anisotropic strain can engineer the crystal symmetry, structural domain morphology, and growth orientation of ultrathin Hf0.5Zr0.5O2 (HZO) films. Epitaxial ultrathin HZO films were grown on the heterostructures of (001)- and (110)-oriented La2/3Sr1/3MnO3/SrTiO3 (LSMO/STO) substrate. Various structural analyses revealed that the (110)-oriented substrate promotes a higher degree of structural order (crystallinity) with improved stability of the (111)-oriented orthorhombic phase (Pca21) of HZO. Conversely, the (001)-oriented substrate not only induces a distorted orthorhombic structure but also facilitates the partial stabilization of nonpolar phases. Electrical measurements revealed robust ferroelectric properties in epitaxial thin films without any wake-up effect, where the well-ordered crystal symmetry stabilized by STO(110) facilitated better ferroelectric characteristics. This study suggests that tuning the epitaxial growth of ferroelectric HZO through substrate orientation can improve the stability of the metastable ferroelectric orthorhombic phase and thereby offer a better understanding of device applications.

Advancements and challenges in BaTiO3-Based materials for enhanced energy storage

Numerous researchers worldwide have been motivated to develop highly effective, environmentally acceptable green energy sources as a result of the recent sharp increase in energy use and the need for low emission levels. The energy generated from various renewable sources can be stored efficiently with a system that has a high energy density and high energy efficiency. Due to their enhanced dielectric, ferroelectric, and breakdown strength characteristics, BaTiO3 based dielectric/ferroelectric ceramic materials have received a lot of interest for energy storage applications in the past tw decades. In the present work, a thorough analysis of recent advancements in composites and single-phase BaTiO3 materials with enhanced energy storage performance. This review's main focus is on the crucial tactics and theoretical frameworks for improving the energy efficiency and recovered energy storage density of various BaTiO3-based materials. A thorough summary has been provided with the most recent developments in BaTiO3 based materials for multi-layered ceramic capacitors (MLCCs), pulse power capacitors, piezoelectric transducers, energy harvesting, electric vehicle batteries, and high-power electronic devices in order to confirm the commercial applications of BaTiO3 based single phase as well as multi-phase layered structures and composites.

Structural refinement, dielectric and ferroelectric properties of Cr modified Ba0·90Sr0·10TiO3 ceramics

In this study, we investigated the impact of Chromium substitution on the structural, dielectric and ferroelectric characteristics of Ba0·90Sr0·10Ti1-3x/4CrxO3 (x = 0, 0.005, 0.010, 0.015 and 0.020) ceramics fabricated by solid state reaction method. Rietveld refinement of X-ray diffraction pattern confirmed tetragonal perovskite structure for all the samples. Based on the crystal structure and the lattice parameter obtained through XRD measurement, the Madelung energy of each sample was computed. SEM images revealed a reduction in grain size with rising Cr concentration. TEM, HRTEM, SAED and EDS analysis was carried out for BST-Cr3 sample. Diffused rings observed in Selective Area Electron Diffraction (SAED) patterns indicate the crystallinity of the sample. EDS analysis indicated the presence of Ba, Sr, Ti, O and Cr elements. In the temperature range of 30 °C–150 °C, dielectric measurements (dielectric constant ‘ε’ and tangent loss ‘tanδ’) have been made at different frequencies (1, 10, 50, 100 and 1000 kHz). The samples displayed a diffused phase transition, with noticeable reduction in Curie temperature ‘Tc’ and tangent loss ‘tanδ’ with the substitution of Cr. Polarization versus electric field loops were recorded at different electric fields (5, 10, 15, 20 and 25 kV/cm) and improved values of remnant polarization ‘Pr’ and coercive field ‘Ec’ were observed. A lower Ec value facilitates easier domain movement within the unit cell, leading to enhanced ferroelectric properties. Temperature dependent P-E loops indicated that as the temperature increased, the material became softer accompanied by simultaneous reduction in Pr and Ec values.

Achieving large strain and low hysteresis in BiFeO3-BaTiO3-based piezoelectric ceramics

The high strain hysteresis has impeded lead-free piezoelectric ceramics to replace lead zirconate titanate ceramics applied in actuators. In this study, we report a significant advancement with the synthesis of a novel BiFeO3-BaTiO3-(Ba0.6Sr0.4)TiO3 (BF-BT-BST) system. The optimal composition has demonstrated a remarkable strain of 0.42 % coupled with a notably low hysteresis of 21 %. It is found that the incorporation of BST into BF-BT facilitates the transition from the rhombohedral phase to the pseudo-cubic phase, which in turn significantly enhances the relaxor ferroelectric characteristics of the ceramic. Through adjusting the composition proportion of BST, a unique ferroelectric domain structure is established for the BF-BT-0.04BST ceramic, where polar nanoregions (PNRs) are surrounded by ferroelectric macrodomains. The domain structure enables the ceramic to have the ability to respond the external electric field quickly compared to the PNRs for typical relaxor composition, thereby leading to large strain and low hysteresis simultaneously. Hence, it is inferred that the ferroelectric macrodomains simplify the response process of the PNRs under electric field. This study provides an efficient strategy to break through the bottleneck of large strain hysteresis for BF-BT ceramic, and gives a deep comprehension for the improvement of the strain characteristics.

Investigation of Morphology, Optical and Electronic Ac Conduction of the Olivine Manganite Compound: NaMnPO4

AbstractThe evolution of multifunctional materials is an outstanding research area, which aims to improve the versatility of materials according to their broad domains of usage. Focus interest was paid here to the orthophosphate compound, in particular, the olivine NaMnPO4 material. This compound was synthesized by a solid‐state method and investigated using numerous techniques. Primary room‐temperature structural analysis evidences the sample synthesized in the orthorhombic structure and its phase purity. The sample‘s average grain size was calculated to be around 420 nm. Further, the band gap for our material was found to be (Eg=4.4 eV) by optical analysis of UV‐visible spectroscopy, revealing that our compound is a potential candidate for optoelectronic applications. The electrical behavior study‘s main results confirm the ferroelectric character of the sample and support the aim of deepening the knowledge of the material according to its thermally stimulated conduction processes through impedance spectroscopy. Electrical studies revealed the dominant transport processes across various temperature and frequency ranges, leading to the NSPT model. The frequency dependency relates to frequency‐dispersive dielectric spectra, conduction mechanisms, and relaxation phenomena. The obtained results show perspective and suggest that the material under study has a wide range of potential electronic applications.

Enhanced structural, magnetodielectric, and multiferroic response in Fe and Co Co-doped Barium strontium titanate ceramics

In this paper, the ambient temperature multiferroic effect resulting from the incorporation of transition metal ions (Fe3+ and Co2+) in lead-free BST [ Ba0.7Sr0.3(Fex/2Cox/2)Ti1−xO3;x=0,0.01,0.03,0.05,0.07 ] ceramics synthesized via the solid-state reaction (SSR) procedure has been thoroughly analyzed. The investigation consistently scrutinized the effects of augmenting transition metal co-doping on the structural, ferroelectric, dielectric, magnetic, and magnetodielectric characteristics. The x-ray diffraction (XRD) patterns for all ceramic compositions demonstrated the formation of a monophasic (P4mm) crystalline structure. The Raman analysis evidenced the presence of various modes, which are associated with the occurrence of the single-phase and provide strong corroboration for the x-ray diffraction observations. Scanning electron micrographs reveals that the inclusion of transition metal ions results in the diminution of grain size. The frequency-dependent dielectric characteristics were represented over the frequency range of 1 kHz to 1 MHz. The P-E hysteresis curves demonstrate a consistent reduction in the values of Ps and Pr, whereas, the M-H curve reveals the enhancement in magnetic properties with increased doping. The magnetodielectric analysis confirmed the interplay between the ferroelectric and ferromagnetic ordering. The BST-1CF sample exhibited the highest MC % value of 5.30% along with the magnetoelectric coupling coefficient ‘γ’ of −6.01×10−1(memu/g)−2, making it a favorable entrant for the advancement of innovative non-volatile multiferroic memory gadgets.

Fluorite-structured antiferroelectric hafnium-zirconium oxide for emerging nonvolatile memory and neuromorphic-computing applications

The rapid progress of the internet of things, cloud computing, and artificial intelligence has increased demand for high-performance computing. This demand has led to a focused exploration of novel nonvolatile memory (NVM) and brain-inspired neuromorphic-computing electronics, with research efforts directed at identifying materials compatible with complementary metal-oxide-semiconductor technology. Exploring fluorite-structured hafnium-zirconium oxide (HZO) mixed oxides has revealed promising ferroelectric (FE) and memristor characteristics, suggesting potential applications in emerging technologies. However, certain intrinsic properties of HZO-based FEs, such as high coercive fields (Ec) and polarization metastability, may pose challenges for commercial viability. Recent investigations of fluorite-structured HZO-based antiferroelectrics (AFEs) have highlighted their advantages, including lower energetic barriers, higher switching speeds, and a uniform phase distribution. These inherent benefits position fluorite-structured HZO-based AFEs as potential candidates within the NVM landscape. Furthermore, the accumulated polarization and spontaneous depolarization characteristics of fluorite-structured HZO-based AFEs make them worthy of potential integration into neuromorphic-computing because they resemble certain aspects of neuron behavior. Despite these positive aspects, a more thorough exploration and consideration are needed to address existing challenges. This review aims to present fluorite-structured HZO-based AFE materials and highlight the current challenges, possible applications, and future opportunities and can act as an update for recent developments in these intriguing materials and provide guidance for future researchers in the optimization and design of HZO-based AFE materials and devices for emerging NVM and neuromorphic-computing applications.

Improving energy storage properties of NN-NBT ceramics through compositional modification

Na0.5Bi0.5TiO3(NBT)-based ceramics are materials with good energy storage properties and non-ergodic relaxation ferroelectric properties, as well as high Curie temperature and good temperature stability. Herein, a new approach was devised to adjust the non-ergodic relaxation ferroelectric characteristics of Na0.5Bi0.5TiO3(NBT)-based ceramics by introducing NaNbO3 into Na0.5Bi0.5TiO3(NBT) (x NN-(1-x) NBT, where x= 0.17, 0.19, 0.21, 0.23, and 0.25). To overcome limitations of NBT, additional constituents with antiferroelectric properties were introduced to create binary solid solutions with NBT to yield NN-NBT ceramics with antiferroelectric properties for optimized energy storage applications. As-obtained NN-NBT ceramics revealed multiphase structures with rhombic (R3c) and tetrahedral (P4bm) phases. Coexisting strongly and weakly coupled polar nanoregions (PNRs) resulted in relatively high polarization (Pmax) and reduced polarization of reflection (Pr). The optimized 0.21NN-0.79NBT ceramic exhibited recoverable energy storage density of ≈2.84 J·cm−3 at 180 kv·cm−1 with energy storage efficiency of 78%. Structural characterization indicated the existence of intermediate phases modulation phases with coexisting antiferroelectric phase and relaxation ferroelectric phase. Overall, proposed NBT-based non-ergodic relaxation ferroelectric ceramics look promising for effectively improving energy storage performance, providing new prospects for the development of advanced pulse capacitors.

Structural phase coexistence enhances the energy storage density of (Bi0.5Na0.5)0.8Ba0.2Ti1-ySnyO3 lead-free ceramics

In the present study, BaSnO3 was introduced into polycrystalline NBT-BT ferroelectric ceramics and conducted a comprehensive investigation into the structural, dielectric, ferroelectric, and energy storage characteristics of the (Bi0.5Na0.5)0.8Ba0.2Ti1-ySnyO3 (BNBTS) ceramics. The coexistence of structural phases P4mm and Amm2 was observed through Rietveld refinement and also confirmed by Raman analysis. The formation energy decreases with an increase in substitution concentration favouring the formation of the orthorhombic phase. The SEM analysis revealed a denser microstructure characterised by smaller grain sizes, which favourably enhances energy storage density. Furthermore, Raman spectroscopic analysis unveiled a softening of Ti–O bonds, indicating the emergence of macroscopic relaxor behaviour. Dielectric studies provided evidence of a transition from ferroelectric to relaxor behaviour, an observation further confirmed by P-E loop measurements. This transition can be linked to the partial substitution of Sn4+ ions for Ti4+ ions, disrupting the ferroelectric long-range order within the matrix phase. Notably, the polarization-electric field (P-E) loop of BNBTS2 ceramics exhibited a substantial value of polarization (Ps) 30 μC/cm2 with a reduced value of remnant polarization (Pr) 2.29 μC/cm2. These characteristics contributed to the achievement of higher energy recovery (Wrec) and lower energy loss (Wloss) values, measuring 1.184 J/cm3 and 0.142 J/cm3, respectively, with a notable efficiency of 88.8%. Consequently, the system of ternary ceramics demonstrates promise as a potential option for energy storage ceramics among NBT-BT-based materials.

Ferroelectric memory devices using hafnium aluminum oxides and remote plasma-treated electrodes for sustainable energy-efficient electronics

In this work, we adopt a low-temperature sustainable plasma treatment approach for the fabrication of ferroelectric memory devices. From our experimental results, we found that the ferroelectric polarization characteristics of HfAlOx ferroelectric device could be further improved by using low-temperature nitrogen plasma treatment on bottom TiN electrode for surface modification. The low-temperature nitrogen plasma treatment on TiN bottom electrode not only prevent electrode oxidation, but also lowers the generation of defect traps at the interface between ferroelectric HfAlOx and TiN bottom electrode during high-temperature ferroelectric annealing process. Besides, the nitrogen-treated bottom electrode also can improve bias-stress induced instability and cycling endurance of HfAlOx ferroelectric devices due to the effective suppression of randomly distributed defect traps or oxygen vacancies near the surface of bottom electrode.

Downscaling grain size toward the nanometre range – A key-factor for tuning the crystalline structure, phase transitions, dielectric and ferroelectric behaviour in Ba0·8Sr0·2TiO3 ceramics

The present study aims to describe the role of the grain size on the properties of submicron- and nano-structured Ba0·8Sr0·2TiO3 (BST) ceramics. Dense (1 − 2% porosity) ceramics with average grain sizes in the range of (77 − 234) nm were consolidated under different spark plasma sintering conditions starting from nanopowders with a mean particle size of 70 nm, synthesized via the acetate variant of the sol-gel method. The structural analysis based on XRD data revealed a mixture of cubic and tetragonal modifications at room temperature for the precursor powders and for all the investigated ceramics. The structural heterogeneity of the individual ceramic grains with coexistence of cubic and tetragonal polymorphs was confirmed by HR-TEM investigations. Accordingly, a “brick-wall" model with cubic grain boundary regions and tetragonal grain cores is proposed. By increasing the grain size, from 77 to 234 nm, a decrease of the phase transitions diffuseness accompanied by an increase of the permittivity maxima (from 650 to 4500) and dielectric losses (from 5 to 7.5%, at 100 Hz), was detected by broadband dielectric spectroscopy. No variation of the Curie temperature in the investigated Ba0·8Sr0·2TiO3 ceramics was detected, unlike typically reported for BaTiO3 ceramics with similar grain sizes. The Curie-Weiss temperature and the Curie constant decrease when grain size is diminished, indicating an overall reduction of the ferroelectric active volume, as a scaling effect. The ferroelectric switching was demonstrated for all the selected fine-grained BST ceramics, either at nanoscale or macroscopically, with an increased ferroelectric character for the coarser submicron-structured ceramics, with respect to the nanocrystalline one. The observed properties of the fine-grained Ba0·8Sr0·2TiO3 ceramics are explained in the frame of multiphase coexistence and ferroelectricity “dilution” due to the increasing role of non-ferroelectric grain boundaries when reducing grain size and complete the knowledge on the scale-dependent properties of dense fine-grained BaTiO3-based ceramics.

Endowing Ferroelectric Properties of Tetragonal Lysozyme Crystals through C60 Doping

The inherent nonpolarity of tetragonal lysozyme crystals excludes a ferroelectricity response. Herein, we present a demonstration of achieving measurable ferroelectricity in tetragonal lysozyme crystals through C60 doping. Ferroelectric characterizations revealed that C60-doped tetragonal lysozyme crystals exhibited typical characteristic ferroelectric hysteresis loops. Crystallographic structural analysis suggested that C60 doping may induce a reduction in the overall symmetry of tetragonal Lys@C60, leading to the observed ferroelectricity response. Moreover, the introduction of C60 facilitates efficient electron transport inside the crystal and influences the polarization of Lys@C60, further contributing to the observed ferroelectricity response. This work verifies that C60 doping can serve as a simple strategy to bestow novel ferroelectric properties to non-ferroelectric lysozyme crystals, potentially rendering them suitable for biocompatible and biodegradable application in implantable and wearable bioelectronics.

Development of ferroelectricity with crystallographic phase transformation in Hf0.5Zr0.5O2 thin films upon initial stimulation of an electric field exceeding the coercive field

This study demonstrates a drastic transformation of ferroelectricity and crystallographic phase in Hf0.5Zr0.5O2 (HZO) thin films through the first stimulation of an electric field larger than the coercive field in metal-ferroelectric-metal (MFM) capacitors. Initially, capacitance–voltage (C–V) measurements in fresh MFM capacitors with voltage sweep smaller than the coercive field indicated constant capacitance value without hysteresis. Applying the electric field exceeding the coercive field subsequently, the C–V behavior changed to a typical dual-peak ferroelectric feature in positive and negative sweeps. X-ray diffraction analysis of the HZO layers before and after a single electric-field application revealed small-angle shifts in diffraction peaks, confirming a crystallographic phase transformation induced by the single electric-field stimulation exceeding the coercive field. These results suggest a possibility that the first electric field apply initiates development of ferroelectric phase transformation from a non-ferroelectric phase.

Influence of sintering temperature on the electrical properties of SrTiO3–BaZrTiO3 ceramics for energy storage applications

The impact of the sintering temperature on the phase composition and electrical properties of 5%SrTiO3–95%BaZr0.15Ti0.85O3 (ST-BZT) ceramics fabricated by solid-state method and consolidated by two-step sintering is presented. A systematic analysis of the phase composition, microstructures, dielectric, ferroelectric, and energy storage characteristics. A di-phase SrTiO3–BaZrTiO3 composite is obtained at low sintering temperatures below 1400 °C. Increasing the sintering temperature causes a shift of the Curie temperature from 62 °C to 55 °C together with changes of permittivity values and of the ferroelectric loops, thus indicating a progressive interdiffusion process at the interfaces, together with a better densification. Remarkably, the ST-BZT composition sintered at 1500 °C exhibits characteristics of a single phase (Ba,Sr) (Zr,Ti)O3 solid solution, with high room temperature permittivity around 2950 and good ferroelectric response (saturation polarization Pmax = 12.6 μC/cm2 and remnant polarization Pr = 2.16 μC/cm2). Consequently, this composition displays a much greater recoverable energy density (Wrec = 54.5 mJ/cm3) in comparison to the ones of the di-phase ST-BZT composites and the parent phases. However, the (Sr0.05Ba0.95) (Zr0.14Ti0.86)O3 solid solution, demonstrates a lower energy efficiency (72%) in comparison to the ST-BZT di-phase composites sintered at lower temperatures, which exhibit higher energy efficiency values around 86%. In addition, the charge-discharge experiments were performed under different electric fields to disclose the difference in energy storage properties in 5%SrTiO3–95%BaZr0.15Ti0.85O3 ceramics. This suggests that the sintering strategy plays a crucial role in determining the energy efficiency of the obtained ceramics. Additionally, all the investigated ST-BZT ceramics present high energy efficiency at low-applied electric fields, suggesting their potential as candidates for energy storage capacitors operating at moderate fields.

Effect of the number and distribution of Al2O3 atomic layer deposition cycles within HfO2 layer on ferroelectric characteristics

We comprehensively analyze the effects of the number and distribution of Al2O3 atomic layer deposition (ALD) cycles into a 10-nm-thick HfO2 matrix on the ferroelectric switching behavior. An ALD cycle containing one pulse for Hf (or Al) precursor and one pulse of water as reactant is repeated 150 times for the given thickness of 10 nm. Spontaneous remnant polarization (Pr) is enabled through the formation of crystalline Al-doped HfO2 (Al:HfO2) by incorporating at least two Al2O3 ALD cycles evenly into the HfO2 film under annealing at 600 °C for 3 min following W top electrode (TE) deposition. When more than four Al2O3 cycles are used, the Al elements function as leakage sources rather than stressors, resulting in an open hysteresis loop and a weak endurance of 105 cycles. Notably, an improved 2 Pr of ∼9 μC/cm2 is achieved when the Al2O3 layers are concentrated near the lower region of the HfO2. On the other hand, as the Al2O3 layers are intensively located in the upper region of the HfO2, a dielectric response is observed in the polarization–voltage and current–voltage measurements. Our results indicate that the two mechanical stresses induced by the Al dopant with a size smaller than Hf and the difference in the thermal expansion coefficient between TE and Al:HfO2 effectively activate both the lower and upper sites. Therefore, many dipoles are observed to participate in the polarization owing to the stresses that are applied evenly throughout the Al:HfO2 layer to form the orthorhombic phase.

Interface engineering for facile switching of bulk-strong polarization in Si-compatible vertical superlattices

Ferroelectric thin films incorporating different compositional layers have emerged as a promising approach for enhancing properties and performance of electronic devices. In recent years, superlattices utilizing various interactions between their constituent layers have been used to reveal unusual properties, such as improper ferroelectricity, charged domain walls, and negative capacitance in conventional ferroelectrics. Herein, we report a symmetry scheme based on the interface engineering in which the inherent cell-doubling symmetry allowed atomic distortions (phonons) in any vertically aligned superlattice activate novel interface couplings among atomic distortions of different symmetries and fundamentally improve the ferroelectric properties. In a materialized case, the ionic size difference between Hf4+ and Ce4+ in the HfO2/CeO2 (HCO) ferroelectric/paraelectric superlattice leads to these couplings. These couplings mitigate the phase boundary between polar and non-polar phases, and facilitate polarization switching with a remarkably low coercive field (Ec\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${E}_{c}$$\\end{document}) while preserving the original magnitude of the bulk HfO2 polarization and its scale-free ferroelectric characteristics. We show that the cell-doubled distortions present in any vertical superlattice have unique implications for designing low-voltage ferroelectric switching while retaining bulk-strong charge storing capacities in Si-compatible memory candidates.

Enhancing ferroelectric performance in hafnia-based MFIS capacitor through interface passivation and bulk doping

In recent times, there has been a notable surge of interests in hafnia (HfO2)-based ferroelectrics, primarily due to their remarkable ferroelectric properties employed in ultra-thin configurations, alongside their compatibility with the conventional CMOS manufacturing process. In order to harness the full potential of HfO2-based films for high-performance non-volatile memory applications, it is imperative to enhance their ferroelectric characteristics and durability. This study introduces a straightforward approach aimed at augmenting the ferroelectric performance of Hf x Zr1−x O2 (HZO) films deposited on silicon (Si) substrates through the engineering of oxygen vacancies (V O). The results of this endeavor demonstrate a significant enhancement in ferroelectric performance, characterized by a 2Pr value of 47 μC cm−2 and impressive endurance, enduring up to 108 cycles under an 8 MV cm−1 electric field without the need of a wake-up process. This marked improvement can be attributed to a dual-pronged approach, involving the incorporation of an Al2O3 interlayer and the introduction of Al atoms into the HZO film. The Al2O3 interlayer primarily serves to mitigate the presence of oxygen vacancies at the interface, while the introduction of Al dopants elevates the concentration of oxygen vacancies within the bulk material. This modulation of oxygen vacancy concentration proves instrumental in facilitating the formation of a ferroelectric o-III phase within the HZO-based films, thereby further augmenting their ferroelectric performance. This innovative and effective strategy offers an alternative avenue for enhancing the ferroelectric properties of materials characterized by a fluorite crystal structure.

Opportunity of ferrimagnetic (CZLF)/ferroelectric (BZT) composite materials in high frequency applications

AbstractThe ferrimagnetic Zn0.35Co0.65 La0.02Fe1.98O4 (CZLF) ferrite with cubic spinel structure (space group Fd3m) was made into composite by mixing with ferroelectric Ba0.5Zr0.5TiO3 (BZT) perovskite with tetragonal structure (space group P4mm) at the mass ratio. Disk-shaped composite powder was finally heated at 1100 °C to study the structure, dielectric and ferroelectric properties. The structural characterization for synthesized samples were carried out using Fourier transform infrared and Transmission Electron Microscopy. Fourier transform infrared show the successful formation of composite samples which is also observed from x-ray diffraction pattern. In compared to their ferrite counterparts before the composite, dielectric response and ferroelectric characteristics of the composite samples are noticeably altered. Compared to the ferrite samples, the composite system exhibits a higher permittivity. In composite samples, the space charge polarization, which was primarily effective at low frequencies and high measurement temperatures, is much diminished. The mechanical properties and indentation creep of these bearing alloys were studied by Vickers indentation testing at room temperature. The remnant polarization of BZT/CZLF increases with decreasing BZT content, which may be suitable for permanent memory device applications. Graphical abstract