Strain Electric Field Research Articles

Investigation of electric field-induced phase transitions in unfilled tungsten bronze relaxor ceramics designed by the high entropy concept

Electric field-induced phase transition behaviour, extensively studied in perovskite-structured ceramics, has not been previously reported in unfilled tetragonal tungsten bronze (TTB) structured ceramics. In this work, we present the first investigation of electric field-induced phase transitions in high entropy designed unfilled TTB structured Ca0.25Sr0.25Ba0.25Pb0.25Nb2O6 (CSBP) ceramics using dielectric and ferroelectric characterization techniques. The findings reveal that field-induced polarization in the CSBP ceramics evolve from irreversible to reversible with increasing temperature. Furthermore, relaxor ferroelectric behaviour was observed in the ceramics, attributed to the A-site cation disorders in the unfilled TTB structure, facilitated by the high entropy design. The absence of non-180° domain switching was indicated by microstructural observations and analysis of the strain-electric field (S-E) response. In-situ poling synchrotron studies and experimental S-E response measurements revealed an electrostrictive behaviour characterized by an electrostrain not originating from macroscopic structural transformations or long-range domain switching but more likely contributed by the reorientation of polar nanoregions. The results obtained provide a foundation for future studies investigating the electric field-induced phase transition and domain switching behaviour in the unfilled TTB structured ceramics.

Theoretical and Experimental Raman Investigation of Mechanical Strain and Electric Field Effects on Conductive Polymers.

Mechanical strain and electric field affect the performance of conductive polymer devices, for which the underlying mechanism should be investigated at the molecular level. This study combines theoretical and experimental Raman approaches to explore the changes in the molecular structure of poly(3-hexylthiophene) (P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT) under the influence of mechanical strain and external electric fields. Theoretical calculations reveal the pronounced shifts in the main Raman peak if the conjugating length is changed by the mechanical strain, while in experiments, the peak position is unaffected under tensile and bending strain. Under an external electric field, the theoretical results predict a continuous red shift of the main Raman peak accompanied by the change in bond lengths, while in experiments, the same peak exhibits a red shift at an initial increase of the electric field strength and then becomes almost unchanged at a stronger electric field. The discrepancies between calculation and experimental results are attributed to the complex nature of the conjugated chains and noncrystalline domain present in the organic semiconductors, which limits the effectiveness of strain and electric field on the conjugated chains. The results of this study help to bridge the gap between the theoretical study and the actual response of conductive polymers for flexible and electronic device applications.

Strain and External Electric Field Engineering of S-Terminated MXene on Selective and Sensitive Detection of N-Containing Compound Gases: A Computational Study.

Gas sensors are used for monitoring hazardous gases and vapors. With the emergence of S-terminated MXene synthesis, herein, we explore the sensing ability of Ti3C2S2 toward N-containing gases, including NH3, NO, NO2, trimethylamine (TMA), and nicotine (NT), using first-principles calculations and a statistical thermodynamic model. We find that Ti3C2S2 exhibits high selectivity to TMA, NO, and NT with moderate adsorption energies of -0.610, -0.490, and -0.476 eV, respectively, minimizing environmental noise from ambient gases. The electronic structure of Ti3C2S2 subtly alters upon adsorption of TMA, NO, and NT, facilitating detectable signals in the sensing device. However, the adsorption of NO2 and NH3 is less pronounced due to weak physisorption (<0.3 eV). Employing engineering strategies including biaxial strain and an external electric field greatly enhances the selectivity and sensitivity of NO2 (NH3) detection by boosting adsorption strength up to -0.351 eV with ε = 5% (-0.370 eV with |E⃗| = 0.6 V/ Å). In addition, the moderate adsorption energies of the gases result in a suitable recovery time in the range of milliseconds, leading to high reusability of the sensing device. The estimated adsorption densities suggest potential coverage of these N-containing molecules even at low concentrations and room temperature. Computational analysis of the sensing capability of Ti3C2S2 using the nonequilibrium Green's function method indicates that it is a promising gas-sensing material. In addition, mechanical modifications, electric field adjustments, and gate voltage alterations could be used to obtain effective sensing materials for N-containing gas detection.

Electrical contact property and control effects for stable T(H)-TaS2/C3B metal-semiconductor heterojunctions.

Metal-semiconductor heterojunctions are the basis for developing new electronic devices. Here, T(H)-TaS2/C3B metal-semiconductor heterostructures are constructed by different phase T- and H-TaS2 monolayers combined with the C3B monolayer. The calculated corrected binding energies, phonon band structures, elastic constants, and molecular dynamics simulations indicated that both heterojunctions are highly stable, meaning that T(H)-TaS2/C3B heterojunctions possibly exist in experiments. The electronic property calculations showed that the intrinsic T(H)-TaS2/C3B heterojunction is an n(p)-type Schottky contact with a low Schottky barrier height (SBH), which is very important for the design of high-performance field-effect transistors. The electronic properties of the T(H)-TaS2/C3B heterojunctions can be controlled by varying the vertical strain and external electric field; however, the strain only resulted in a small change in the heterojunction SBH. Nevertheless, under external electrical field control, the T-TaS2/C3B heterojunction could manage a transition from an n-type Schottky contact to an n-type Ohmic contact and the H-TaS2/C3B heterojunction could be altered from a p-type Schottky contact to a p-type Ohmic contact. These findings provide theoretical insights into the electronic and electrical contact properties of the T(H)-TaS2/C3B heterojunction, which could be beneficial for developing n-type MOS and p-type MOS transistors.

Flexoelectric anisotropy and shear contributions in lead-free piezocomposites

Flexoelectricity is the coupling between strain gradients and electric fields. This phenomenon can significantly enhance piezocomposite response in addition to linear piezoelectricity. This enhancement is especially important for lead-free piezocomposites, which generally underperform compared to lead-based counterparts. Flexoelectric enhancement is facilitated by structural anisotropy in piezocomposites. However, challenges in modeling flexoelectric effects arise from several unknowns. Firstly, the shear flexoelectric coefficient is not well-characterized experimentally. Secondly, significant discrepancies exist between theoretical predictions and experimental measurements of flexoelectric coefficients. Thirdly, the influence of matrix mechanical properties on flexoelectric behavior is poorly understood. To address these issues, we construct a parametric flexoelectric model of a lead-free piezocomposite with graded inclusion concentration. We then systematically analyze the impact of each parameter to identify which significantly influence flexoelectric behavior. This study is intended to provide direction to further experimental studies towards understanding and tailoring this subset of parameters.

Exploring tunable optoelectronic properties of two-dimensional GaS/PtSSe heterostructures under biaxial strain and external electric field

Vertically stacked heterostructures offer novel material options for designing tunable optoelectronic devices due to their adjustable electronic and optical properties. This work compares the electronic structure, charge transfer, and optical properties of two different contact faces of GaS/Janus PtSSe heterostructures using the density functional theory. The results show that GaS/PtSSe form a built-in electric field at the interface, directing from the monolayer GaS to the PtSSe. GaS/SePtS and GaS/SPtSe are determined to be indirect bandgap semiconductors with bandwidths of 1.51 eV and 1.11 eV utilizing the PBE. In this study, the band alignment of GaS/PtSSe can induce a semiconductor-to-metal transition. Notably, GaS/SePtS is highly sensitive to biaxial strain and external electric field, transitioning its energy band alignment from Type-I to Type-II. Applying tensile strain enhances the sunlight absorption of GaS/PtSSe, making it a promising candidatein the tunable electronic devices and photodetectors.

Structural phase transition, relaxor behavior, and ultra-low strain hysteresis in BaTiO3 ceramics modified by BiYO3

In this study, the structural properties, phase transition, relaxor behavior, and strain properties of (1−x)BaTiO3‒xBiYO3 (x= 0.02‒0.15 mol) ceramics were investigated. The room temperature x-ray diffraction and Raman spectroscopy results reveal that (1−x)BaTiO3‒xBiYO3 ceramics undergo phase transition from tetragonal to pseudo-cubic structure with x increasing. The curves of dielectric constant and loss tangent as a function of temperature and frequency show that the dielectric constant was changing from being dependent on temperature to being independent of it upon increasing BiYO3 amount, which is induced obvious dielectric relaxation behavior. Slimmer polarization–electric field (P–E) loops and lower remnant polarization (Pr ) were observed for samples with x ⩾ 0.08. The transition between the ferroelectric and relaxor states leads to the narrow strain–electric field (S–E) loops, which exhibit a high electric field-induced strain of 0.192% and an ultra-low strain hysteresis of 10.4% at an electric field of 70 kV cm−1 for x= 0.04. This excellent performance indicates that 0.96BaTiO3‒0.04BiYO3 ceramic may be promising lead-free materials for high-precision displacement actuators applications.

Controllable electrical contact characteristics of graphene/Ga2X3 (X = S, Se) ferroelectric heterojunctions

Reducing the interface barrier between metals and semiconductors is crucial for designing high-performance optoelectronic devices based on van der Waals heterojunctions (HJs). This study proposes four models of HJs composed of graphene (GR) and Ga2X3 (X = S, Se) and systematically investigates their interface electronic properties, along with strain engineering and electric field effects. The results indicated that exploiting the interface dipole-induced potential step allows modulation of the Schottky barrier height (SBH) and contact type of the HJs by altering the contact interfaces. In the BGR/Ga2S3 HJs (BGR means GR positioned at the bottom of Ga2X3), only a small positive (negative) electric field is required to realize the transition from n-type Schottky to p-type Schottky (Ohmic) contacts. Also, strain engineering provides additional means for flexible and controllable contact types, facilitating the design of reversible logic circuits. It indicates the physical insights and strategic interventions of GR/Ga2X3 HJs tunable SBH and offers theoretical guidance for the design of two-dimensional ferroelectric nanodevices with high-quality electrical contact interfaces.

First-principles study of the electronic and optical properties of two-dimensional PtS2/GaS van der Waals heterostructure

Heterostructures based on two-dimensional materials have received increasing attention due to their extraordinary properties and application potential. In this paper, the electronic and optical properties of the PtS2/GaS van der Waals (vdW) heterostructure as well as the effects of biaxial strain and external electric field are systematically investigated based on first-principles calculations. The PtS2/GaS vdW heterostructure has an interlayer distance of 3.01 Å and is a type-Ⅱ semiconductor of band gap 1.54 eV. Large optical absorption coefficients are observed in both the ultraviolet and the visible regions. Furthermore, its band structure can be effectively tuned by applying biaxial strain and external electric field. The transition between the type-Ⅱ and type-I band alignments can be realized. The absorption spectra and their peaks can be then manipulated effectively by applying biaxial strain with good stability under external electric field. The predicted tunable electronic properties and unique optical absorption properties suggests promising potential for the application of the PtS2/GaS vdW heterostructure in future optoelectronic nanodevices.

Modulation of electronic and optical properties of Bi2Se3/MoTe2 heterostructure by vertical strain and external electric field

Based on the first-principles, the electronic and optical properties of Bi2Se3/MoTe2 van der Waals heterostructure (vdWH) under vertical strain and electric field are studied. The calculated results show that the Bi2Se3/MoTe2 is a type-II band alignment with an indirect band gap of 4.6 meV. Compressive strain can increase interfacial charge transfer, the refractive index, reflectivity and absorption coefficient in the infrared region. The electric field can regulate the energy band gap but has little effect on the optical properties. Importantly, the combined action of positive electric field of 0.11 VÅ−1 and vertical strain with the interlayer distance of 2.90 Å, leads to the reflectivity reaching 88 %. The absorption coefficient is up to 0.7×106 cm−1 in the visible region. The fundamental reason is that the contribution coming from Bi-pz, Te-pz and Mo-dz2 orbital increase near the Fermi level. These research results provide a theoretical basis for material design and device optimization.

Dielectric probing of low-temperature degradation resistance of commercial zirconia bio-ceramics

ObjectivesTo investigate the effect of the stability of oxygen vacancies on the low-temperature degradation (LTD) resistance of two kinds of commercial zirconia-based materials (3Y-TZP ceramics and Ce-TZP/Al2O3 composites) via the dielectric probing methods. MethodsThe commercial 3Y-TZP ceramics and Ce-TZP/Al2O3 composites were prepared via conventional solid-state methods. Density, phase content, microstructure, strain, and biaxial flexural strength (BFS) of two materials were investigated using Archimedes method, XRD, SEM, strain-electric field (S-E) loops and ball-on-ring methods, respectively. The concentration of oxygen vacancies before and after LTD of two materials were evaluated using dielectric probing and XPS methods. ResultsThe XRD analysis revealed that compared to the 3Y-TZP ceramics, the Ce-TZP/Al2O3 composites showed better LTD resistance, without clear LTD. The greater LTD resistance for Ce-TZP/Al2O3 composites was associated with their stability of oxygen vacancies, by higher activation energy based on the dielectric measurements and XPS results. For the 3Y-TZP ceramics that underwent the tetragonal to the monoclinic phase transition during the LTD treatment, the concentration of their oxygen vacancies decreased after LTD. In addition, the Ce-TZP/Al2O3 composites exhibited higher flexural strength and potential fracture toughness based on the BFS testing and strain vs electric field measurement results, indicating a great potential for use in fixed restorative dental applications. SignificanceThis work suggested the stability of oxygen vacancies played a key role in the resistance to LTD. Optimizing the stability of the oxygen vacancies is key to the development of more reliable zirconia- based dental biomaterials with greater resistance to LTD.

Theoretical predicted Janus SrAlGaTe4: effects of strain and electric field and its topological properties

The asymmetric Janus SrAlGaTe4, constructed from its parent SrGa2Te4 monolayer, was predicted theoretically by first principle calculations. Its stability was confirmed by phonon structure without imaginary frequency and ab initio molecular dynamics (AIMD) simulations. The Janus structure reduces the symmetry of SrGa2Te4 monolayer, which causes the absence of topological states in free-standing Janus SrAlGaTe4. To explore the possible electronic and topological properties, the effects of strain and external electric field, working as effective modulation methods for the electronic properties, were investigated. The SrAlGaTe4 monolayer undergoes a direct-to-indirect bandgap transition when the in-plane biaxial compressive strain is −8%. When the tensile strain is 9% or the electric field is 0.5 V Å−1, the Janus SrAlGaTe4 monolayer exhibits topological insulator (TI) characters, which was confirmed by the evolution of the Wannier charge centers (WCC). And the critical values for the topological transition are 2% for the biaxial tensile strain, and 0.2 V/Å for the applied electric field. The asymmetric Janus structure induces a Rashba spin splitting not only in the valence band but also in the conduction band near the Fermi level when the spin–orbit coupling (SOC) is present. Our findings offer theoretical insights into the exotic physical properties of SrAlGaTe4 and also provide guides to new spintronic device designs.

Tunability of 2D Graphene/H-diamane heterostructure under external electric field and strain engineering

Heterostructures have various physical and chemical properties compared to single-layer two-dimensional materials (2DMs), providing an effective method for improving optoelectronic device's performance. ln this work, we systematically examined the electronic structures, contact types, and optical properties of the Graphene/H-diamane heterostructure (Gr/H-diamane HTS) made of Gr and 2D H-diamane by the first-principles method. This HTS displays a p-type Schottky contact with a Schottky barrier height (SBH) of 0.01 eV. The SBH can be effectively tuned by applying electric field (EF) and strain engineering, and the transition from Schottky contact to Ohmic contact can be realized under vertical strain or external EF, which contributes to the improvement of device performance. In addition, the Gr/H-diamane HTS has a work function difference of 0.61 eV and a strong absorption capacity for infrared, visible, and ultraviolet light. Its peak absorption coefficient in the infrared region reaches 4 × 106 cm-1 and can be improved even further under EF. Therefore, the Gr/H-diamane HTS has enormous potential in applications including high-performance nanoelectronics and infrared photodetectors.

On the Lanthanide Effect on Functional Properties of 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 Ceramic.

The beneficial effects of lanthanide incorporation into 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (BNT-BT) matrix on its functional properties were investigated. The conventional solid-state method was used for synthesizing samples. The structural refinement revealed that all samples crystallized in R3c rhombohedral symmetry. Raman spectroscopy study was carried out using green laser excitation and revealed that no clear perceptible variation in frequency is observed. Dielectric measurements unveiled that the introduction of rare earth obstructed the depolarization temperature promoted in BNT-BT, the diffusive phase transition decreasing with increasing lanthanide size. Only dysprosium addition showed comparable diffusion constant and dielectric behavior as the unmodified composition. Further, the comparison of the obtained ferroelectric hysteresis and strain-electric field loops revealed that only Dy-phase exhibited interesting properties comparing parent composition. In addition, the incorporation of lanthanides Ln3+ into the BNT-BT matrix led to the development of luminescence characteristics in the visible and near infrared regions, depending on the excitation wavelengths. The simultaneous occurrence of photoluminescence and ferroelectric/piezoelectric properties opens up possibilities for BNT-BT-Ln to exhibit multifunctionality in a wide range of applications.

Tuning structural and electronic properties of Stanene-based nanotube by strain and transverse electric field: First-principles investigation

In this work, we investigate the effects of applying strain and transverse electric field on the geometrical parameters and the electronic properties of (5,5) Stanene-based nanotube (SnNT) using density functional theory (DFT) calculations. The results reveal that the geometrical parameters such as diameter and buckling parameter affect by applying strain. Moreover, it is found that the studied nanotube exhibits direct and indirect band gap under tensile and compressive strain, respectively. In addition, the band gap energy decreases by increasing the compressive strain until the semiconductor to metal phase transition occurs. The external transverse electric field leads to separate degenerated states in the band structure and reduces the band gap energy of nanotube. Tuning the electric field induces semiconductor to metal transition. To further examine the electronic properties of (5,5) SnNT, the effective mass of charge carriers is calculated under applied strains and transverse electric fields.

Exploring electronic characteristics of bilayer HfS2 under mechanical strain and external electric field: A first-principles approach

This study employed the density functional theory (DFT) to explore the dynamic stability of different stacking configurations of bilayer HfS2 (2L-HfS2) and the influence of external conditions on its electronic properties. These results indicate that the AA configuration is the most stable among the various stacking configurations. Calculations of the carrier effective mass revealed that the artificially stacked 2L-HfS2 maintained a small effective mass of electrons and holes and exhibited high carrier mobility. Further investigation revealed diverse trends in the electronic properties of 2L-HfS2 under vertical strain, in-plane strain, shear strain, and an applied external electric field. These variations encompass bandgap size alterations, band structure evolution, and transitions in the metallic behavior. This systematic study elucidates the regulatory effects of different strains and external electric field conditions on the electronic properties of 2L-HfS2, thereby providing a vital theoretical foundation and experimental guidance for its application in electronics and optoelectronics.

Ultrahigh Piezoelectric Response Obtained by Artificially Generating a Large Internal Bias Field in BiFeO3–BaTiO3 Lead‐Free Ceramics

AbstractPiezoelectric actuators are vital devices that convert electrical signals into mechanical strain, offering rapid and precise responses. Lead‐based piezoceramics have traditionally been the preferred choice for commercial piezoelectric actuators, while the low Curie temperature and the rising environmental concerns hinder their applications at high temperatures. In this study, a novel strategy is proposed to achieve high piezoelectric responses in lead‐free 0.67Bi1.05FeO3–0.33BaTiO3 (67BF‐33BT) ceramics with high Curie temperature by artificially generating a large internal bias field through repeat poling and aging treatments. A comprehensive exploration of how this internal bias field responds to applied electric fields and temperature variations has been conducted. The results suggest that the internal bias field originates from two aspects, one arises from the free charges that compensate for the depolarization field, while the other is attributed to the highly oriented defect dipoles. As a result of this internal bias field, the ceramics exhibit asymmetric strain–electric field (S–E) behaviors, resulting in a high strain (ε = 0.21%) and an extremely high piezoelectric coefficient (d33* = 1033.70 pm V−1) when subjected to low electric field (20 kV cm−1), along with good temperature stability from room temperature (RT) to 100 °C.

High pyroelectric performance and its dependence on the field‐induced orientation in antiferroelectric PLZST system

AbstractIn antiferroelectrics (AFE), the recovery of AFE phase from field‐induced ferroelectric (FEIN) phase occurs at the depolarization temperature, Td. In this study, we report an exceptionally high pyroelectric coefficient, p ≈ 16.00 × 10−2 C/m2 K at ∼70°C in the AFE composition Pb0.982La0.012(Zr0.60Sn0.30Ti0.10)O3 which lies close to FE‐AFE phase boundary. We closely examine this FEIN‐AFE transformation in virgin and poled samples, during heating, by temperature‐dependent X‐ray diffraction, polarization, strain–electric field hysteresis, dielectric and pyroelectric studies and report, for the first time, the mechanism responsible for this behavior.

Achieving ultrahigh piezoactuation constant of 2240 pm/V and giant electrostrain of 1.12% simultaneously in BNT-based polycrystalline ceramics

Ultrahigh electrostrain (Sm) at low driving field in lead-free piezoceramics could alleviate key concerns by reducing energy consumption and the risk of electrical breakdown for advanced applications. However, the giant electrostrain always accompanied with an extremely large drive field is a long-standing conflict referred as the strain-electric field trade-off. Herein, we engineer a novel strategy of introducing the B-site unequal double doping cations (ZnSn0.5)4+ into (Bi0.5Na0.5)0.93Ba0.07TiO3 ceramic to generate the spontaneous phase transition from relaxor state to ferroelectric state, polar nanoregions PNRs and defect cluster. The giant strain of Sm= 1.12% is achieved by integrating the field-induced phase transition, morphotropic phase boundary MPB and the enhanced synergistic effect between the spontaneous polarization Ps and the defect cluster polarization Pd under a low electric field of 50 kV/cm, thus yielding extremely large piezoactuation constant d33 * =2240 pm/V in (Bi0.5Na0.5)0.93Ba0.07Ti0.97(ZnSn0.5)0.03O3 piezoceramics. This finding also demonstrates an unexpected new route to design novel ferroelectric materials via nonconventional mechanisms.

Tunable d33/d33* for MPB (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 lead-free piezoceramic by crystallographic texturing approach

The morphotropic phase boundary (MPB) Ba0.85Ca0.15Zr0.10Ti0.90O3 composition is successfully transferred into <001>-textured ceramic having Lotgering factor f-74 % (abbreviated as BCZT-T74) using high aspect ratio BaTiO3-template particles via templated grain growth (TGG) method. The microstructural aspects reveal the distinctive grain growth formation for non-textured (BCZT-NT) and textured (BCZT-T74) ceramics; confirming the proper grain growth formation for textured ceramics. The polarization behavior was tested at 1 Hz, 5 Hz, and 10 Hz electric field frequencies by applying a voltage bias of 1000 V; the BCZT-NT ceramics show more variation in remnant polarization (Pr) as well as maximum polarization (Pmax) peak position while BCZT-T74 ceramics exhibit nearly steady values. The frequency-dependent variation in Pr (i.e. ΔPr) for non-textured and textured BCZT ceramics is ±11.08 % and ±3.25 % respectively in the frequency range 1Hz–10Hz at an applied voltage bias of 1000 V. The bipolar strain-electric field (S-E) butterfly loop evidences the typical piezoelectric nature; for both non-textured and textured BCZT ceramics having the effective piezoelectric strain coefficient d33* of 576 pm/V and 657 pm/V respectively. The BCZT-NT and BCZT-T74 ceramics revealed the average positive strain % values of 0.063 % and 0.1123 % and negative strain % values of 0.003985 % and 0.02281 % respectively at the applied voltage 1000 V functioning at 1Hz. The enhancement in negative strain% for BCZT-T74 ceramics is > 5.70 times higher than BCZT-NT ceramics. The variation in positive strain (i.e. ΔS+ve) and variation in negative strain (i.e. ΔS-ve) for non-textured ceramics is ±11.74 % and ±67.34 %, however, for textured ceramics is only ±3.33 % and ±5.00 % respectively. The BCZT-NT and BCZT-T74 ceramics exhibit the piezoelectric charge coefficient (d33) of 370 pC/N and 520 pC/N (1.4 times that of BCZT-NT ceramics) respectively. The electrostrictive coefficient (Q33) of BCZT-T74 ceramics is 0.039 m4/C2, which is > 2 times higher than BCZT-NT ceramics as well as commercially used toxic PZT-5H ceramics. Therefore, less variation in a strain, as well as polarization nature with varying frequencies and enhancement in piezo properties, suggests the present textured MPB BCZT-T74 ceramics is a promising candidate for piezoelectric devices functioning at the wide range of applied electric field frequencies.