BaTiO3 Layer Research Articles

A surface plasmon resonance nanostructure containing graphene and BaTiO3 layers for sensitive defection of organic compounds.

Organic compound-based sensors are used in a variety of significant fields, including medical research, azeotropic calibration, vegetable oil extraction, the shoe industry and geothermal power plants. Here, a high-performance, two-dimensional material-based organic compound sensor has been proposed using a surface plasmon resonance (SPR) nanostructure consisting of a BK7 glass prism, Ag, BaTiO3, Ag, graphene and sensing layer. The reflectivity curves of the SPR device have been investigated when the sensing media are Pentane, n-Hexane, n-Heptane and n-Octane. The thickness of the BaTiO3 layer and the number of graphene sheets have been optimized to maximize the sensitivity. The highest sensitivity attained is 220.83 deg/RIU for n-Octane with 45 nm silver/10 nm BaTiO3/8 nm silver and four layers of graphene. We believe that the SPR-based sensors are simple and can replace the spectrometry, chromatography and electrochemical based sensors. The proposed design is extremely effective for diverse applications in biological, industrial and chemical detection because of its simple structure and great performance.

Oxygen vacancy region formation in BaTiO3 adjacent to the interface between the internal electrode and the dielectric layer in Ni–Sn internal electrode multilayer ceramic capacitor exhibiting leakage current suppression

This study underlines the ceramic BaTiO3 dielectric layer adjacent to the electrode of long-term reliability-improved Ni–Sn alloy internal electrode BaTiO3-based multilayer ceramic capacitor to clarify the cause of electric barrier formation. Electron energy loss spectroscopy measurements of the Ti L 3,2 near the edges and the O K near the edge structure changes to characterize the existence of an oxygen vacancy region, approximately 60 nm in width, and generated in BaTiO3 adjacent to the interface. Accordingly, the n-type semiconductor layer of BaTiO3 that originated from the oxygen vacancies, led to the formation of a rigid Schottky barrier at the interface.

Hollow-structured BaTiO3 nanoparticles with cerium-regulated defect engineering to promote piezocatalytic antibacterial treatment

The low efficiency of mechanical energy capture and insufficient active sites are the main obstacles of piezocatalytic therapy. Herein, cerium (Ce)-doped hollow BaTiO3 (hBTCe) nanoparticles (NPs) were developed to improve the piezocatalytic effect through simultaneously hollow structure and defect engineering. hBT NPs were prepared through precipitation of TiO2 layers on SiO2 NP templates, transformation into BaTiO3 layer, and simultaneous removal of SiO2 cores. The hollow structure exhibits a stronger piezoresponse than solid NPs, and the piezoelectric coefficient increases nearly 2.6 times. The Ce doping enhances polarization, oxygen vacancy formation and electron/hole separation, and reduces the band gap of hBTCe NPs. Both the strong piezoelectric current and abundant generation of reactive oxygen species from hBTCe under ultrasonication contribute to significant destructions of planktonic bacteria and biofilms. Thus, this study demonstrates the Ce-regulated defect engineering and hollow structure of piezoelectric NPs are effective to promote polarization, piezoelectric potential and piezocatalytic antibacterial therapy.

High-performance self-powered amorphous-BaTiO3/p-Si heterojunction photodetector controlled by ferroelectric effect

The coupling of ferroelectric and photoelectric effects provides a promising alternative for enhancing the performance of the photodetectors. Here, a high-performance self-powered UV–visible photodetector enhanced by the ferroelectric effect has been demonstrated on amorphous BaTiO3/p-Si heterojunction. When the depolarization field in the ferroelectric BaTiO3 layer is in the same direction as the built-in field at the heterojunction, the responsivities of the device at 0 V can be significantly improved to 14 mA/W, 27 mA/W, and 223 mA/W at 254 nm, 365 nm, and 600 nm, respectively, which is superior to any other reported BaTiO3-based self-driven photodetectors. In addition, the device possesses a quick response speed with rising/fall times of 450 µs/460 µs at 254 nm and 80 µs/140 µs at 600 nm. Moreover, due to the defect-assistant recombination of photogenerated carriers at the amorphous BaTiO3/p-Si interface and grain boundaries in amorphous BaTiO3, the spike of transient photocurrent can be visualized under 254 nm illumination. This work presents a novel strategy for the design and research of high-performance self-powered photodetectors.

Anti-thermal quenching in phytochrome-active AC-Driven electroluminescence from β-Ga2O3:Cr3+ powder phosphor

β-Ga2O3, a wide bandgap oxide material, has attracted recently scientific attention in optoelectronics, especially electroluminescent (EL) devices. It is good as a host material for transition metals and rare-earth elements. Herein, a NIR emitting alternating current (AC)-driven powder-based electroluminescent (PEL) device is introduced with superior thermal stability from a β-Ga2O3:Cr3+ phosphor. It consists of β-Ga2O3:Cr3+ and BaTiO3 layers that serve as active and insulating layers, respectively, which are fabricated by a facile and cost-effective screen-printing method on the ITO glass substrate. Under the AC source, it emits the NIR spectrum, which is optically attributed from the spin-allowed and spin-forbidden transitions of Cr3+ ions and well overlapped with the phytochrome absorption spectrum. The strategies to obtain the optimum condition of the phosphor for EL purposes are presented with parameters of annealing temperatures as well as Cr3+ concentrations. Further analysis shows a promising application in harsh environments with thermal stability, so-called, anti-thermal quenching phenomenon up to 200 °C (473 K). This work can provide a worthwhile realization and method of large-area NIR emitting devices based on the β-Ga2O3 phosphor.

Electrical stimulation of piezoelectric BaTiO3 coated Ti6Al4V scaffolds promotes anti-inflammatory polarization of macrophages and bone repair via MAPK/JNK inhibition and OXPHOS activation

Bone regeneration is a highly synchronized process that requires multiple biochemical, bioelectrical, mechanical, and other physiological cues. The restoration and delivery of electrical cues locally through piezoelectric materials have been demonstrated to facilitate osteogenesis in vitro and bone repair in vivo. However, the underlying mechanism by which piezoelectric stimulation promotes osteogenesis and bone repair remains unclear yet, limiting the design and clinical application of piezoelectric materials for bone repair. Herein, a piezoelectric BaTiO3/Ti6Al4V (BT/Ti) scaffold was prepared by hydrothermal synthesis of a uniform BaTiO3 layer on three dimensionally printed Ti6Al4V scaffold. The BT/Ti scaffolds exhibited piezoelectricity and favorable biocompatibility with RAW264.7 macrophages after polarization. In vitro results demonstrated that the piezoelectric effects of the poled BT/Ti scaffolds promoted M2 polarization of macrophages and immunoregulatory osteogenesis of MC-3T3 osteoblasts. In a subcutaneous implantation model, a higher proportion of CD68+ CD206+ M2 macrophages was observed in the tissues around the poled BT/Ti scaffolds under low intensity pulsed ultrasound (LIPUS) stimulation. Improvements in macrophage M2 polarization and bone regeneration were further identified in a sheep cervical corpectomy model. RNA sequencing and mechanistic investigation revealed that the piezoelectric BT/Ti (poled) scaffolds inhibited the inflammatory MAPK/JNK signaling cascade and activated oxidative phosphorylation (OXPHOS) and ATP synthesis in macrophages. Collectively, our study provides a promising method for regulating the immune microenvironment and enhancing bone regeneration using polarized piezoelectric BT/Ti scaffolds.

Simulation and Optimization of FAPbI3 Perovskite Solar Cells with a BaTiO3 Layer for Efficiency Enhancement.

Since the addition of BaTiO3 in perovskite solar cells (PSCs) provides a more energetically favorable transport route for electrons, resulting in more efficient charge separation and electron extraction, in this work we experimentally prepared such a PSC and used a modeling approach to point out which simulation parameters have an influence on PSC characteristics and how they can be improved. We added a layer of BaTiO3 onto the TiO2 electron transport layer and prepared a PSC, which had an FTO/TiO2/BaTiO3/FAPbI3/spiro-OMeTAD/Au architecture with a power conversion efficiency (PCE) of 11%. Further, we used the simulation program SCAPS-1D to investigate and optimize the device parameters (thickness of the BaTiO3 and absorber layers, doping, and defect concentration) resulting in devices with PCEs reaching up to 15%, and even up to 20% if we assume an ideal structure with no interlayer defects. Our experimental findings and simulations in this paper highlight the promising interplay of multilayer TiO2/BaTiO3 ETLs for potential future applications in PSCs.

Combining Freestanding Ferroelectric Perovskite Oxides with Two-Dimensional Semiconductors for High Performance Transistors.

We demonstrate the fabrication of field-effect transistors based on single-layer MoS2 and a thin layer of BaTiO3 (BTO) dielectric, isolated from its parent epitaxial template substrate. Thin BTO provides an ultrahigh-κ gate dielectric effectively screening Coulomb scattering centers. These devices show mobilities substantially larger than those obtained with standard SiO2 dielectrics and comparable with values obtained with hexagonal boron nitride, a dielectric employed for fabrication of high-performance two-dimensional (2D) based devices. Moreover, the ferroelectric character of BTO induces a robust hysteresis of the current vs gate voltage characteristics, attributed to its polarization switching. This hysteresis is strongly suppressed when the device is warmed up above the tetragonal-to-cubic transition temperature of BTO that leads to a ferroelectric-to-paraelectric transition. This hysteretic behavior is attractive for applications in memory storage devices. Our results open the door to the integration of a large family of complex oxides exhibiting strongly correlated physics in 2D-based devices.

BTO-Coupled CIGS Solar Cells with High Performances

In order to improve the power conversion efficiency (PCE) of Cu(In,Ga)Se2 (CIGS) solar cells, a BaTiO3 (BTO) layer was inserted into the Cu(In,Ga)Se2. The performances of the BTO-coupled CIGS solar cells with structures of Mo/CIGS/CdS/i-ZnO/AZO, Mo/BTO/CIGS/CdS/i-ZnO/AZO, Mo/CIGS/BTO/CdS/i-ZnO/AZO, Mo/CIGS/CdS/BTO/i-ZnO/AZO, Mo/CIGS/BTO/i-ZnO/AZO, Mo/CIGS/CdS/BTO/AZO, and Mo/ CIGS/CdS(5 nm)/BTO(5 nm)/i-ZnO/AZO were systematically studied via the SCAPS-1D software. It was found that the power conversion efficiency (PCE) of a BTO-coupled CIGS solar cell with a device configuration of Mo/CIGS/CdS/BTO/AZO was 24.53%, and its open-circuit voltage was 931.70 mV. The working mechanism for the BTO-coupled CIGS solar cells with different device structures was proposed. Our results provide a novel strategy for improving the PCE of solar cells by combining a ferroelectric material into the p-n junction materials.

Biocompatibility and colorectal anti-cancer activity study of nanosized BaTiO3 coated spinel ferrites

In the present work, different nanoparticles spinel ferrite series (MFe2O4, Co0.5M0.5Fe2O4; M = Co, Mn, Ni, Mg, Cu, or Zn) have been obtained via sonochemical approach. Then, sol–gel method was employed to design core–shell magnetoelectric nanocomposites by coating these nanoparticles with BaTiO3 (BTO). The structure and morphology of the prepared samples were examined by X-ray powder diffraction (XRD), scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscope (HR-TEM), and zeta potential. XRD analysis showed the presence of spinel ferrite and BTO phases without any trace of a secondary phase. Both phases crystallized in the cubic structure. SEM micrographs illustrated an agglomeration of spherical grains with nonuniformly diphase orientation and different degrees of agglomeration. Moreover, HR-TEM revealed interplanar d-spacing planes that are in good agreement with those of the spinel ferrite phase and BTO phase. These techniques along with EDX analyses confirmed the successful formation of the desired nanocomposites. Zeta potential was also investigated. The biological influence of (MFe2O4, CoMFe) MNPs and core–shell (MFe2O4@BTO, CoMFe@BTO) magnetoelectric nanocomposites were examined by MTT and DAPI assays. Post 48 h of treatments, the anticancer activity of MNPs and MENCs was investigated on human colorectal carcinoma cells (HCT-116) against the cytocompatibility of normal non-cancerous cells (HEK-293). It was established that MNPs possess anti-colon cancer capability while MENCs exhibited a recovery effect due to the presence of a protective biocompatible BTO layer. RBCs hemolytic effect of NPs has ranged from non- to low-hemolytic effect. This effect that could be attributed to the surface charge from zeta potential, also the CoMnFe possesses the stable and lowest zeta potential in comparison with CoFe2O4 and MnFe2O4 also to the protective effect of shell. These findings open up wide prospects for biomedical applications of MNPs as anticancer and MENCs as promising drug nanocarriers.

Designing a Bimodal BaTiO3 Artificial Layer to Boost the Dielectric Effect toward Highly Reversible Dendrite-Free Zn Metal Anodes.

With the growing interest in suppressing greenhouse gas emissions from fossil fuel combustion, the implementation of electrical energy storage devices for efficiently utilizing renewable energy is expanding worldwide. Zn-ion batteries are attractive for energy storage because of their safety, eco-friendliness, high energy density, and low cost. However, their commercialization is hindered by the poor rechargeability of the zinc anode because of Zn dendrite growth and hydrogen evolution. Herein, we present the application of an artificial layer composed of bimodal BaTiO3 particles on Zn metal to boost the dielectric properties and thus enhance the reversibility of Zn anodes during long-term cycling. The BaTiO3 layer induces electric polarization under external electric fields, causing the Zn ions to move sequentially toward the Zn anode. Moreover, its mechanical characteristics alleviate the volume changes between the BaTiO3 layer and Zn metal. Consequently, Zn dendrite growth is effectively inhibited, and the electrochemical performance is significantly improved in Zn|Zn symmetric cells, resulting in a low overvoltage (39 mV) and stable cycling (800 h) at 1 mA cm-2. Moreover, the Zn-ion full cell using an α-MnO2 cathode exhibits consistent capacity retention up to 380 cycles. This study demonstrates a new strategy to economically and readily suppress dendrite formation by using bimodal dielectric particles as artificial layers to stabilize metal-based batteries.

Reducing leakage current and enhancing polarization in multiferroic 3D super-nanocomposites by microstructure engineering

Multiferroic materials have generated great interest due to their potential as functional device materials. Nanocomposites have been increasingly used to design and generate new functionalities by pairing dissimilar ferroic materials, though the combination often introduces new complexity and challenges unforeseeable in single-phase counterparts. The recently developed approaches to fabricate 3D super-nanocomposites (3D‐sNC) open new avenues to control and enhance functional properties. In this work, we develop a new 3D‐sNC with CoFe2O4 (CFO) short nanopillar arrays embedded in BaTiO3 (BTO) film matrix via microstructure engineering by alternatively depositing BTO:CFO vertically-aligned nanocomposite layers and single-phase BTO layers. This microstructure engineering method allows encapsulating the relative conducting CFO phase by the insulating BTO phase, which suppress the leakage current and enhance the polarization. Our results demonstrate that microstructure engineering in 3D‐sNC offers a new bottom–up method of fabricating advanced nanostructures with a wide range of possible configurations for applications where the functional properties need to be systematically modified.

2D Z-scheme heterojunction and oxygen deficiency synergistically boosting the photocatalytic activity of a layered BaTiO3/BiOIO3 composite

Simultaneously enhancing the quantity, separation efficiency and redox capability of photo-excited carriers to boost the catalytic activity has always been the toughest challenge for a photocatalyst. Herein, we presented a novel BaTiO3/BiOIO3 layered composite by proposing a synergistic strategy of 2D Z-scheme heterojunction and rich oxygen deficiency. Due to the high-quality interfaces with strong coupling interaction and stable IO3−/I− redox pairs between BaTiO3 and BiOIO3 layers, the composite was endowed concurrently with the strengthened photo response, separation efficiency and high redox capability of photo-excited carriers through a Z-scheme migration pathway. DFT computation emphasized that the formation of IO3−/I− redox pair and band gap of the composite were highly related to oxygen deficiency. Moreover, the ·O2− radicals can be expansively stimulated by the well-known local surface plasmon resonance effect of oxygen deficiency via inducing extra hot electrons. As a result, the composite performed a 4.4-fold enhanced photocatalytic activity than pure BaTiO3 toward the photo-degradation of tetracycline, which can be completed in just a few minutes. Therefore, we hope that the proposed heterojunction and oxygen deficiency synergistic boosting the photocatalytic activity of BaTiO3 could open a lot of insights for developing more efficient composite photocatalysts to solve the water pollutions.

Dielectric property and tunability of multilayer BST-BTO thin film in the terahertz range

The dielectric property and tunability of Ba0.6Sr0.4TiO3 (BST) and BaTiO3 (BTO) multilayer thin film were investigated by using terahertz time-domain spectroscopy (THz-TDS) at room temperature. The film samples used in the study had a same total thickness but different numbers of periodic layer N (a single BTO layer plus a single BST layer) and different layer thickness ratios x (x for total BTO layer thickness to total film thickness; 1-x for total BST layer thickness to total film thickness). We found that the permittivity of the samples declined with the increase of N, which can also be modulated by external optical pumping. The dielectric loss of the sample with N = 1 was much higher than that of other samples, which could be attributed to the interfacial polarization between BST and BTO thin films. In short, the dielectric property of layered BST-BTO composite structure can be appreciably changed by selecting the number of periodical layers and the corresponding layer thickness. These results indicate that the multilayer thin film structure is possible for the applications of tunable photonic devices in the terahertz range.

Optically Induced Picosecond Lattice Compression in the Dielectric Component of a Strongly Coupled Ferroelectric/Dielectric Superlattice (Adv. Electron. Mater. 6/2022)

Ultrafast Optical Excitation The structure of an epitaxial BaTiO3/CaTiO3 ferroelectric/dielectric superlattice responds to aboveband gap ultrafast optical excitation with a compression of the dielectric CaTiO3 layer is presented in article number 2101051 by Paul G. Evans and co-workers. This unusual response is a consequence of the screening of the polarizing field due to the ferroelectric BaTiO3 layer. The distortion is developed on the picosecond timescale and is apparent in ultrafast x-ray free-electron laser diffraction measurements.

Dielectric and ferroelectric properties of multilayer BaTiO3/NiFe2O4 thin films prepared by solution deposition technique

In this work different lead-free multilayered structures, composed of perovskite BaTiO3 and spinel NiFe2O4 thin layers, were obtained by solution deposition method. Structural characterization of the sintered thin films confirmed the well-defined layered structure with overall thickness from 160 to 600 nm, crystalline nature of perovskite BaTiO3 and spinel NiFe2O4 phases without secondary phases (after sintering below 900 °C) and grains on nanometer scale. Dielectric properties of the multiferroic multilayer BaTiO3/NiFe2O4 thin films were analyzed in temperature and frequency range from 30 °C to 200 °C and 100 Hz to 1 MHz, respectively. In comparison to the pure BaTiO3 films, the introduction of ferrite layer reduces dielectric response and increases low frequency permittivity dispersion of the multilayer thin films. The multilayer samples have shown relatively low dielectric loss with stronger contribution of conductivity at higher temperatures, and characteristic broad peak representing “relaxation” of the interface charge accumulation.

Ab Initio Computations of O and AO as well as ReO2, WO2 and BO2-Terminated ReO3, WO3, BaTiO3, SrTiO3 and BaZrO3 (001) Surfaces

We present and discuss the results of surface relaxation and rumpling computations for ReO3, WO3, SrTiO3, BaTiO3 and BaZrO3 (001) surfaces employing a hybrid B3LYP or B3PW description of exchange and correlation. In particular, we perform the first B3LYP computations for O-terminated ReO3 and WO3 (001) surfaces. In most cases, according to our B3LYP or B3PW computations for both surface terminations BO2- and O, AO-terminated ReO3, WO3, BaTiO3, SrTiO3 and BaZrO3 (001) surface upper layer atoms shift downwards, towards the bulk, the second layer atoms shift upwards and the third layer atoms, again, shift downwards. Our ab initio computes that ReO3, WO3, BaTiO3, SrTiO3 and BaZrO3 (001) surface Γ-Γ bandgaps are always smaller than their respective bulk Γ-Γ bandgaps. Our first principles compute that B-O atom chemical bond populations in the BaTiO3, SrTiO3 and BaZrO3 perovskite bulk are always smaller than near their BO2-terminated (001) surfaces. Just opposite, the Re-O and W-O chemical bond populations in the ReO3 (0.212e) and WO3 (0.142e) bulk are slightly larger than near the ReO2 and WO2-terminated ReO3 as well as WO3 (001) surfaces (0.170e and 0.108e, respectively).

A Pressure Responsive Artificial Interphase Layer of BaTiO3 against Dendrite Growth for Stable Lithium Metal Anodes

AbstractDevelopment of lithium (Li) metal anodes in high‐energy‐density batteries is considerably impeded by uncontrolled dendrite growth, side reactions, and related volume changes. In this work, a pressure responsive artificial interphase layer of piezoelectric BaTiO3 (BTO) is constructed on Li anodes to prevent the formation of Li dendrites. Once protruding Li buds compress the interfacial space, the extruded piezoelectric layer generates an internal electric field to effectively change the local electric field around the bud tips, thus promoting homogeneous plating/stripping of Li. The artificial interphase layer not only offers a physical protection to the Li anode, but also helps to regulate the Li flux at the Li/electrolyte interface, which then leads to the uniform Li deposition. Consequently, the BTO‐protected Li anode exhibits stable cycling and small polarization in both Li||Li and Li||Cu cells. When paired with S, LiFePO4 and Ni‐rich high‐voltage cathodes, the Li‐metal batteries also exhibit improved cycling stability and high Coulombic efficiency.

A transmission electron microscopy study of low-strain epitaxial BaTiO3 grown onto NdScO3

Ferroelectric materials exhibit a strong coupling between strain and electrical polarization. In epitaxial thin films, the strain induced by the substrate can be used to tune the domain structure. Substrates of rare-earth scandates are sometimes selected for the growth of ferroelectric oxides because of their close lattice match, which allows the growth of low-strain dislocation-free layers. Transmission electron microscopy (TEM) is a frequently used technique for investigating ferroelectric domains at the nanometer-scale. However, it requires to thin the specimen down to electron transparency, which can modify the strain and the electrostatic boundary conditions. Here, we have investigated a 320 nm thick epitaxial layer of BaTiO3 grown onto an orthorhombic substrate of NdScO3 with interfacial lattice strains of −0.45% and −0.05% along the two in-plane directions. We show that the domain structure of the layer can be significantly altered by TEM sample preparation depending on the orientation and the geometry of the lamella. In the as-grown state, the sample shows an anisotropic a/c ferroelastic domain pattern in the direction of largest strain. If a TEM lamella is cut perpendicular to this direction so that strain is released, a new domain pattern is obtained, which consists of bundles of thin horizontal stripes parallel to the interfaces. These stripe domains correspond to a sheared crystalline structure (orthorhombic or monoclinic) with inclined polarization vectors and with at least four variants of polarization. The stripe domains are distributed in triangular-shaped 180° domains where the average polarization is parallel to the growth direction. The influence of external electric fields on this domain structure was investigated using in situ biasing and dark-field imaging in TEM.

Signatures of enhanced out-of-plane polarization in asymmetric BaTiO3 superlattices integrated on silicon

In order to bring the diverse functionalities of transition metal oxides into modern electronics, it is imperative to integrate oxide films with controllable properties onto the silicon platform. Here, we present asymmetric LaMnO3/BaTiO3/SrTiO3 superlattices fabricated on silicon with layer thickness control at the unit-cell level. By harnessing the coherent strain between the constituent layers, we overcome the biaxial thermal tension from silicon and stabilize c-axis oriented BaTiO3 layers with substantially enhanced tetragonality, as revealed by atomically resolved scanning transmission electron microscopy. Optical second harmonic generation measurements signify a predominant out-of-plane polarized state with strongly enhanced net polarization in the tricolor superlattices, as compared to the BaTiO3 single film and conventional BaTiO3/SrTiO3 superlattice grown on silicon. Meanwhile, this coherent strain in turn suppresses the magnetism of LaMnO3 as the thickness of BaTiO3 increases. Our study raises the prospect of designing artificial oxide superlattices on silicon with tailored functionalities.