BaTiO3 SrTiO3 Research Articles

Domain Engineering the Flexoelectric Response of BaTiO3–SrTiO3 Binary Films: A Phase Field Study

Domain Engineering the Flexoelectric Response of BaTiO3–SrTiO3 Binary Films: A Phase Field Study

Effect of microwave heating on the interdiffusion in BaTiO3–SrTiO3 binary ceramic system

An investigation on the effect of microwave heating (2.45 GHz) on the interdiffusion process was carried out and compared with conventional heating for BaTiO3–SrTiO3 binary system in the temperature range of 1200–1400 °C. Interdiffusion coefficients were extracted using Boltzmann–Matano analysis for both heating methods. Consequently, microwave heating was determined to result in higher interdiffusion coefficients compared to conventional heating. Correspondingly, ∼27% decrease in the apparent activation energy of interdiffusion was found which was associated with faster diffusion under electromagnetic irradiation due to increased vacancy concentration and more open lattice structure in Ba-rich regions which could be exploited for unique experimentations and non-equilibrium/non-stoichiometric phase transformations to study their kinetics and formation mechanisms and grasp a better understanding on the dielectric properties of such perovskites.

Layered SrTiO3/BaTiO3 composites with significantly enhanced dielectric permittivity and low loss

Ferroelectric ceramic materials are receiving increasing attention due to their extensive applications in electrical systems. In this work, three-layer BaTiO3/SrTiO3 ceramic composites consisting of one Ba1-xTiO3-SrxTiO3 (at x = 5, 10, 20 and 30) composite interlayer sandwiched by two BaTiO3 outer layers were fabricated. And the effects of SrTiO3 modification on their phase structures, microstructures and dielectric performance were studied in detail. A pure perovskite phase was observed in the Ba1-xTiO3-SrxTiO3 ceramic composites. The BaTiO3 ceramic doping by SrTiO3 exhibited refined grain size. With increased SrTiO3 content, both the permittivity and dielectric loss have increased. Furthermore, a layered structure was designed to enhance the dielectric properties. Consequently, a high permittivity of 7118 and low loss of 0.028 were achieved at 10 kHz in BaTiO3-30 w% SrTiO3–BaTiO3 three-layer ceramic composites. In summary, the introduction of SrTiO3 is believed to reduce the BaTiO3 Curie temperature and greatly improve its permittivity at room temperature. Furthermore, the accumulation of charge carriers at the interface significantly increases the permittivity, while preventing the transport of the charge carriers and reducing the loss. The ultrahigh permittivity and low loss make these composites promising candidates for microwave antennas, field effect transistors and dielectric capacitors.

Effect of BiFeO3 Doping and Annealing Temperature on the High‐Temperature Dielectric Relaxation Properties in BaTiO3–SrTiO3 Lead‐Free Ceramics

Lead‐free xBiFeO3–(1−x)BaTiO3–SrTiO3 solid‐solution ceramics are synthesized and their structure and dielectric and ferroelectric properties are studied. It is observed that the dielectric relaxation process (marked as Region I) triggered by polar nanoregions (PNRs) related to Fe2+/Fe3+ valences may cover the relaxation process induced by oxygen vacancies (OVs, marked as Region II) at 1150 and 1200 °C. The changes in relaxation peak heights show that with the increase of annealing temperature and BiFeO3 content, the PNR concentration increases while OV concentration decreases. Cole–Cole diagram analysis indicates that dielectric relaxations are likely based on changes in grain interior, grain boundary, and the increased electrode/ceramic interface as the doping content increases. The possible causes of relaxation behavior dependence are analyzed in detail.

Defect chemistry for Mn-doped and Nb-doped BiFeO3-based ceramics

BiFeO3 and BiFeO3-based ceramics commonly have high conductivity. Regarding the conduction is n-type, Mn as an acceptor is extensively used to reduce the conductivity. However, p-type conduction has been evidenced recently and Nb as a donor can reduce conductivity. To solve the controversy about the conduction mechanism, Mn-doped and Nb-doped BiFeO3–BaTiO3–SrTiO3 ceramics were studied and the corresponding defect chemistry was discussed. The work reveals some general features related to defects in BiFeO3 and BiFeO3-based ceramics.

Radiation shielding and structural features for different perovskites doped YBa2Cu3Oy composites

The increased demand for ionizing radiation in various fields led to the search for new shielding substances. In this study, five samples of perovskite oxides (BaTiO3, SrTiO3, BaTiO3–SrTiO3, and PbZr0.2Ti0.8O3) doped YBa2Cu3Oy ceramics were prepared to explore their structure and ability for exploitation in the radiation shielding field. The structural properties were explored by using the XRD technique. The XRD results showed an orthorhombic structure for all prepared ceramics. The crystallite size reduces gradually from 96.19 to 66.63 nm with adding different perovskite oxides into the composites. The density shows a variation from about 5.89 to 6.23 g/cm3. The mass attenuation coefficient (MAC) was defined experimentally (MAC)exp and theoretically (MAC)the to check its validity. The maximum relative difference between (MAC)exp and (MAC)the is 7.83%. YBa2Cu3O7/(PbZr0.2Ti0.8O3)2% and YBa2Cu3O7/(BaTiO3–SrTiO3)2% samples showed superior gamma shielding properties and mass stopping power (MSP) for charged particles, respectively, while the pristine YBa2Cu3O7 sample has a better fast neutron removal cross-section (ΣR). From the obtained results, it can be seen a slight variation in shielding properties, indicating the ability to use the different ceramic samples as radiation shielding materials.

4-inch Ternary BiFeO3–BaTiO3–SrTiO3 Thin Film Capacitor with High Energy Storage Performance

4-inch Ternary BiFeO₃–BaTiO₃–SrTiO₃ Thin Film Capacitor with High Energy Storage Performance

Dielectric and electrical energy storage properties of BiFeO3–BaTiO3–SrTiO3 ternary bulk ceramics

Dielectric and electrical energy storage properties of BiFeO3–BaTiO3–SrTiO3 ternary bulk ceramics

Structural and magnetic properties of ferroelectric/dielectric BaTiO3/LaMnO3 and BaTiO3/SrTiO3 heterostructures

We present the results of structural and magnetic properties of two types of heterostructures composed of ferroelectric BaTiO3 and dielectrics LaMnO3 or SrTiO3. By means of the first principle calculations we analyze structures of BaTiO3/LaMnO3 and BaTiO3/SrTiO3 interfaces and investigate magnetic properties and an impact of ferroelectric polarization. Experimental results of magnetic susceptibility measurements for Ba0.8Sr0.2TiO3/LaMnO3 heterostructure are presented.

Microstructure-dependent electrical properties of Bi0.5Na0.5TiO3–BaTiO3–SrTiO3 ternary solid solution

Microstructure-dependent electrical properties of Bi0.5Na0.5TiO3–BaTiO3–SrTiO3 ternary solid solution

The Role of Ferroelectric Polarization in Resistive Memory Properties of Metal/Insulator/Semiconductor Tunnel Junctions: A Comparative Study.

Recently, tunnel junction devices adopting semiconducting Nb:SrTiO3 electrodes have attracted considerable attention for their potential applications in resistive data storage and neuromorphic computing. In this work, we report on a comparative study of Pt/insulator/Nb:SrTiO3 tunnel junctions between ferroelectric BaTiO3 and nonferroelectric SrTiO3 and LaAlO3 barriers to reveal the role of polarization in resistance switching properties. Although hysteretic behaviors appear in current-voltage measurements of all devices regardless of the barrier character, significantly improved current ratios by more than three orders of magnitude are observed in the Pt/BaTiO3/Nb:SrTiO3 tunnel junctions due to the dominance of polarization in modulation of junction barrier profiles between the low and high resistance states. The switchable polarization also gives rise to enhanced resistance retention since the electron diffusion that smears the barrier contrast of the bistable resistance states is suppressed by the polar BaTiO3/Nb:SrTiO3 interface associated with the ferroelectric bound charges. These polarization-induced effects are absent in the nonferroelectric Pt/SrTiO3/Nb:SrTiO3 and Pt/LaAlO3/Nb:SrTiO3 devices in which serious resistance state decay, described by Fick's second law, is observed since there are no switchable interface charges on SrTiO3/Nb:SrTiO3 and LaAlO3/Nb:SrTiO3 to block the electron diffusion. In addition, the Pt/BaTiO3/Nb:SrTiO3 device also exhibits an excellent switching endurance up to ∼4.0 × 106 bipolar cycles. These enhancements indicate the importance of ferroelectric polarization for achieving high-performance resistance switching and suggest that metal/ferroelectric/Nb:SrTiO3 tunnel junctions are promising candidates for nonvolatile memory applications.

Role of WO3 nanoparticles in electrical and dielectric properties of BaTiO3–SrTiO3 ceramics

(BaTiO3–SrTiO3)/(WO3)x ceramics with x = 0 up to 5% were synthesized using solid-state reaction via high-energy ballf milling technique. Various characterization techniques were used including X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform-infrared spectroscopy (FT-IR), and UV–visible diffuse reflectance (DR) spectrophotometer. Structural analysis via XRD indicates the formation of two separate phases of SrTiO3 (STO) and BaTiO3 (BTO) having both cubic structures. The presence of BaWO4 as impurity was detected for higher concentration. SEM observations show a reduction in the average grains size with increasing WO3 addition. In comparison with free-added ceramic, the optical band gap energy (Eg) shows a slight increase with WO3 addition. Contextual investigations on the electrical and dielectric properties of various WO3 added to BTO–STO ceramics have been used to evaluate conductivity ($$\sigma$$), dielectric constant and loss ($$\varepsilon^{\prime}_{r}$$ and $$\varepsilon^{\prime\prime}_{r}$$), and dissipation factor ($$\mathrm{t}\mathrm{a}\mathrm{n}\delta$$) against both frequency and dc bias voltages. Generally, both $$\sigma$$ and $$\varepsilon^{\prime\prime}_{r}$$ correspond to the tendency of the power law to frequency. However, dc bias has been noticed to be lesser affecting the conduction mechanisms, which has a small variation for various WO3 addition ratios. In addition, the dissipation factor was found to be highly dependent on both the addition ratio and the frequency as well as dc bias applied.

Controllable preparation and formation mechanisms of BaTiO3/titanate nanocomposites from solvothermally synthesized K0.8Li0.27Ti1.73O4 crystal

The solvothermal reaction has become a versatile approach to achieve the morphology control of well-defined crystal nanostructures. It is meaningful to improve the titanate precursor by the solvothermal treatment to bring about the structural design of BaTiO3-based materials. In this study, a fiber K0.8Li0.27Ti1.73O4 (KTLO) crystal was prepared by the solvothermal treatment for the first time, and the H1.07Ti1.73O4 (HTO) crystal with a small size and uniform morphology could be transformed from the KTLO crystal. The mesocrystalline BaxSr1-xTiO3 (BST), the mesocrystalline BaTiO3/SrTiO3 (BT/ST) nanocomposite, and the BaTiO3/Bi4Ti3O12 nanocomposite were also prepared by a one- or two-step solvothermal process. A method for the controllable preparation of BST mesocrystals is disclosed. The scientific significances of solvent ratio regulation for obtaining different proportions in BT/titanate nanocomposites are clarified. The crystallographic topochemical relationships between the HTO matrix and the BT/titanate nanocomposite are summarized. This strategy is the development of the novel-prepared precursor for preparing functional materials and revealing of formation mechanisms from the precursor.

Direct Observation of Stable Negative Capacitance in SrTiO3@BaTiO3 Heterostructure

AbstractNegative capacitance in ferroelectrics has seem remarkable progress in recent years. However, direct measurement of negative capacitance has so far been a challenge due to its instable characteristic in the electrostatic field. An ingenious method to design stable negative capacitance by dielectric resonance under high‐frequency alternating electric fields is demonstrated. The well‐pronounced dielectric resonance and electrical property in BaTiO3/SrTiO3 (BT/ST) bulk ceramics consisted of epitaxial core–shell particles are studied. As the negative capacitance can be considered as an inductive behavior, the dielectric resonance of permittivity induced by a LC resonance can be occurred. The dielectric resonance can be described by the Lorentz model and explained by Fano‐like resonance of TO2 phonon in BT. In addition, lowest resonant frequency is observed at effective Curie temperature. Benefiting from negative capacitance in the BT/ST ceramics, both high permittivity and negative permittivity are accompanied with low losses around the resonant frequency, which is useful for developing capacitors and metamaterials. Significantly, this work will provide an initiative avenue to obtain explicit negative capacitance of ferroelectrics in the frequency spectrum.

Traps induced Greens function based mathematical modeling for BaTiO3–SrTiO3 gate stack dual metal GAA MOSFET

In this paper, an analytical model has been developed to analyze the impact of trap charges on Dual Metal Gate-All-Around (DMGAA) MOSFET with BaTiO3–SrTiO3 epitaxial oxide layer as gate stack using Greens function and conformal mapping. Trap charges have been induced to observe the changes in surface potential, electric field and drain current. To further investigate the impact of trap charges the trap density is varied. This enhances the drain current with high ION/IOFF ratio. The analytical results so obtained are compared with the simulated data and are in good agreement thus validating the proposed model. It is also proposed that the device can offer high performance, low leakage power along with high gain and is perfect for analog RF applications. It can be concluded that proposed DMGAA MOSFET is a promising device and a suitable replacement for the existing conventional GAA MOSFETs.

Structural and electronic properties of heterointerface composed of non-polar oxides: SrTiO3 and ferroelectric BaTiO3

We investigate the structural and electronic properties of heterostructure composed of two insulators: ferroelectric BaTiO3 and dielectric SrTiO3, by means of ab initio calculations. Both components of the heterostructure are non-polar in the simple ionic limit. We consider three types of BaTiO3 polarization: non-polar, dipoles towards the interface, and dipoles towards the surface. For the non-polar heterostructure, we obtain that system remains an insulator up to eight BaTiO3 overlayers. However, we show that polarization in the BTO slab induces conductivity. We analyze an impact of ferroelectric polarization onto conducting properties, as well as a possibility of switchable and controllable metal-insulator transition.

Pinning of a ferroelectric Bloch wall at a paraelectric layer.

The phase-field simulations of ferroelectric Bloch domain walls in BaTiO3–SrTiO3 crystalline superlattices performed in this study suggest that a paraelectric layer with a thickness comparable to the thickness of the domain wall itself can act as an efficient pinning layer. At the same time, such a layer facilitates the possibility to switch domain wall helicity by an external electric field or even to completely change the characteristic structure of a ferroelectric Bloch wall passing through it. Thus, ferroelectric Bloch domain walls are shown to be ideal nanoscale objects with switchable properties. The reported results hint towards the possibility to exploit ferroelectric domain wall interaction with simple nanoscale devices.

Dielectric, ferroelectric properties and photoconductivity effect of sol-gel grown SrTiO3/BaTiO3 thin film heterostructure

SrTiO3/BaTiO3 (ST/BT) thin-film heterostructure was deposited on Pt/Ti/SiO2/Si(100) substrate by spin-coating. X-ray diffraction pattern shows that the heterostructure is a perovskite structure composed of ST and BT without any impurity peaks. The dielectric constant and loss of the heterostructure at 10 kHz are 704 and 0.024, respectively. The electric-field dependence of dielectric response was investigated and the tunability of the sample under 200 kV/cm applied field is 21.5%. Compared with pure ST thin film, the polarization-electric field loops of ST/BT heterostructure display high polarization and good symmetry, which could be attributed to the introduction of BT with high dielectric constant and inhibition of the potential pitfalls movement for high barrier at ST/BT interface. Moreover, the heterostructure demonstrates photoconductivity behavior with 405 nm light illumination. The results indicate that ST/BT heterostructure is a potential material in application as multifunctional photoelectric devices.

Electronic Properties of a Two-Dimensional Electron Gas at the Interface between Transition Metal Complex Oxides

The structural and electronic properties of heterostructures based on transition metal oxides containing strongly correlated electrons are compared. The investigated structures are LaAlO3/SrTiO3 (LAO/STO), LaAlO3/BaTiO3 (LAO/BTO), and BaTiO3/SrTiO3 (BTO/STO). The role of structural relaxation in the formation of a two-dimensional electron gas at the interface of two dielectrics is revealed. The contribution from different orbitals and atoms to conductivity is analyzed, along with the correlation between structural distortions induced by the dipole moment in an LAO layer and conductivity.

The Electrocaloric Effect in BaTiO3–SrTiO3 Solid Solution

We have studied the electrocaloric effect in 0.68BaTiO3–0.32SrTiO3 solid solution, as well as the dielectric, pyroelectric, and piezoelectric properties of this compound in the vicinity of the first-order phase transition in a bias electric field. The dielectric and electromechanical contributions to the pyroelectric and electrocaloric effects are discussed.