Ferroelectric Properties Of Bi4Ti3O12 Research Articles

Enhancing ionic conductivity and controlling lithium dendrite growth via ferroelectric ceramic Bi4Ti3O12

BackgroundSolid polymer electrolytes (SPEs) have gained numerous research interest in the field of lithium metal batteries. Solid polymer electrolytes have improved safety compared to liquid electrolytes. Despite this, their low ionic conductivity remains a major barrier to practical applications. To overcome the challenge of low ionic conductivity in SPEs, our study introduces a novel approach that integrates ferroelectric ceramics with polymer solid electrolytes. MethodsWe used a one-step molten salt method to synthesize Bi4Ti3O12 (BIT), combined with a poly (vinylidene difluoride) matrix to form the composite solid-state electrolyte. Through various electrochemical characterizations and COMSOL Multiphysics simulations, we discovered that the ferroelectric properties of BIT significantly increase the dissociation of lithium salts, leading to a greater concentration of mobile lithium ions and more efficient ion transport. Significant findingsThis electrolyte showed a remarkable improvement in lithium-ion conductivity, reaching a value of 8.5 × 10−4 S cm−1 at room temperature. Batteries made with these composite electrolytes demonstrate superior cycling stability, the capacity retention rates for LFP/SPEs/Li cells remain high, reaching 95 % even after 1,000 cycles at room temperature (25 °C). These findings highlight the promising applications of ferroelectric ceramics in solid-state batteries.

Hydrothermal growth of Bi2Ti2O7/TiO2 and Bi4Ti3O12/TiO2 heterostructures on highly ordered TiO2-nanotube arrays for dye-sensitized solar cells

Secure solar energy has been considered to be a possible way to alleviate the energy crisis. Using a hydrothermal reaction, functional heterostructures, including Bi2Ti2O7 and Bi4Ti3O12, were assembled on highly ordered TiO2-nanotube arrays that were prepared via a two-step anodic-oxidation method. The loading of the heterostructure onto the arrays was controlled by adapting the reaction temperature and alkalinity of the hydrothermal reaction. The samples were assembled into dye-sensitive solar cells to study their photoelectric performance. The optimal photoelectric-conversion efficiencies of Bi4Ti3O12/TiO2 (synthesized at 200 °C and pH 13.7) were 2.3 times greater than those of pure TiO2-nanotube arrays. The photoelectric property was enhanced due to the increase in the photoabsorption that originated from the introduction of the dyes, as well as the improvement in the charge-separation efficiency, which was derived from the matching of the energy-bands between the bismuth titanate and TiO2. The ferroelectric properties of Bi4Ti3O12 also played an important role in the enhanced photoelectric property.

Effect of vanadium doping on structural, dielectric and ferroelectric properties of bismuth titanate (Bi4Ti3O12) ceramics

Abstract The effect of vanadium doping on the structural, dielectric and ferroelectric properties of Bi4Ti3O12 (BTO) has been studied. Bi4–x/3Ti3–xVxO12 (x = 0, 0.006, 0.012, 0.018, 0.024 and 0.03 mol%) were prepared using a sol–gel synthesis method and calcined at 400 °C for 3 h. All samples were sintered at 950 °C for 3 h. The relative density of ceramic samples decreases with the addition of vanadium. The structural analysis confirms that no structural changes occur with doping of vanadium into BTO ceramics. Doping of vanadium into BTO ceramics improves its ferroelectric and dielectric properties.

Effect of hydrogen on ferroelectric properties of Bi4Ti3O12 during forming gas annealing

Degradation of Bi4Ti3O12 ferroelectricity during forming gas annealing is investigated by the first-principles method based on the density functional theory(DFT) the generalized gradient approximation(GGA). We calculate the variations of total energy with the displacement of Ti along the c axis, electron density and total density of states in hydrogen-free and hydrogenated models. The results show that the electron densities of Ti-O and Bi-O exhibit significant changes between the Bi4Ti3O12 ferroelectric phases for the hydrogenated and hydrogen-free cases, and the strong hybridization between H and O is favorable to the formation of a convalent bond. The total energy of ferroelectric phase for the hydrogenated case is bigger than that of paraelectric phase because hydrogen incorporation into the lattice has a direct effect on polarization pinning by possibly forming a hydroxyl bond. This demonstrates that hydrogen introduction during forming gas annealing hinders the phase transition of the Bi4Ti3O12 from tetragonal paraelectricity to orthogonal ferroelectricity, and electrical conductivity of Bi4Ti3O12 is increased. This may be an important factor causing severe degradation of Bi4Ti3O12 ferroelectricity.

FERROELECTRIC CHARACTERIZATION AND AC-CONDUCTIVITY PROPERTIES OF Bi4 − xPrxTi3O12 POLYCRYSTALS

ABSTRACT Effects of Praseodymium doping on the ferroelectric properties of Bi4Ti3O12 using dense ceramics were systematically investigated from room temperature to 730°C. DRX studies show that Aurivillius structure can accept low amounts of praseodymium without the precipitation of second phases. Thermoelectric analysis and ferroelectric hysteresis measurements were performed and show that the incorporation of praseodymium modified the transition temperature (Tc) and slightly the polarization values. The incorporation of praseodymium resulted in a variation in the permittivity and in the remnant polarization. The polarization characteristics of the doped samples were different to those of Bi4Ti3O12. AC-conductivity was calculated for each sample and different conduction mechanisms are identified using the typical Arrhenius law.

Ferroelectric and dielectric properties of Nd3+∕Zr4+ cosubstituted Bi4Ti3O12 thin films

Thin films of Nd3+∕Zr4+ cosubstituted Bi4Ti3O12 (BIT), i.e., Bi3.15Nd0.85Ti2.8Zr0.2O12 (BNTZ), were fabricated on Pt∕Ti∕SiO2∕Si(100) substrates by chemical solution deposition and annealed at different temperatures of 600, 650, 700, and 800°C. The effects of annealing temperature on the microstructure, leakage current, ferroelectric, and dielectric properties of the BNTZ films were investigated in detail. Significantly, compared with the Bi3.15Nd0.85Ti3O12 film, the BNTZ thin film has a lower coercive field (2Ec) and leakage current density and a slightly larger remnant polarization (2Pr). It shows that Nd3+∕Zr4+ cosubstitution in BIT film might be an effective way to improve ferroelectric properties of BIT.

Anisotropy of ferroelectric and piezoelectric properties of Bi3.15Pr0.85Ti3O12 thin films on Pt(100)∕Ti∕SiO2∕Si substrates

Bi 3.15 Pr 0.85 Ti 3 O 12 (BPT) thin films with (100) (α(100)=89.1%), (117) (α(117)=83.2%), and (001) (α(001)=99.7%) orientations and a c-axis-oriented (α(001)=99.9%) Bi4Ti3O12 (BT) film were deposited on Pt(100)∕TiO2∕SiO2∕Si substrates using a metal organic decomposition process. Both the values of the remanent polarization (Pr) and coercive field (Ec) of the (001)-oriented BPT film are about 50% higher than those of the BT film with the same orientation, indicating that the ferroelectric properties of BT along the c axis can be improved by doping of praseodymium. Nevertheless, the major polarization vector of BPT is still close to the a axis rather than the c axis due to the fact that the Pr values of the (100)-oriented BPT film are about one and four times larger than those of (117)- and (001)-oriented BPT films, respectively. Based on the volume fractions of (100)-, (117)-, and (001)-oriented grains in BPT films with three orientations, the Pr values of the purely (100)-, (117)-, and (001)-oriented BPT films can be predicated to be about 28.2, 11.1, and 5.3μC∕cm2, respectively. The maximum of the piezoelectric coefficient of BPT can be demonstrated to also be close to the a axis by the piezoelectric measurements using an atomic force microscope in the piezoresponse mode.

Structural, ferroelectric, and dielectric properties of vanadium-doped Bi4−x∕3Ti3−xVxO12

The microstructure, ferroelectric, and dielectric properties of vanadium-doped Bi4Ti3O12 ceramics have been investigated. V substitution is found to cause a transition from an orthorhombic phase to a tetragonal phase at x∼0.03, and again to an orthorhombic phase at higher V content. The ferroelectric properties of Bi4Ti3O12 were significantly improved by V doping. The 2Pr of Bi4Ti3O12 is 16μC∕cm2, and it reaches a maximum value of 26.4μC∕cm2 when the V content is 0.03. The two relaxation peaks (PI, PII) are observed in the dielectric loss (D) curves for all of the samples. The PI and PII peaks related to oxygen vacancies tend to decrease with V doping, which implies the decreasing of the oxygen vacancy concentration caused by V doping and favors the improvement of 2Pr and 2Ec. On the contrary, Raman spectra reveal the occurrence of Ti vacancies when V content is more than x=0.01, which may be responsible for the variation of the microstructure and the deterioration of 2Pr and 2Ec. The ferroelectricity of V doping Bi4−x∕3Ti3−xVxO12 ceramics is therefore likely dominated by these two competing mechanisms, with the optimal ferroelectric properties appearing at V content x=0.03.

Characterization of Ferroelectric Properties of Bi4-xPrxTi3O12 Polycrystals

ABSTRACTEffects of Praseodymium doping on the ferroelectric properties of Bi4Ti3O12 were investigated using dense ceramics from room temperature to 730 °C. DRX and XPS studies shows that the structure can accept only 10% of praseodymium without the precipitation of second phases. Thermoelectric analysis and ferroelectric hysteresis measurements were performed and show that the incorporation of praseodymium modified the transition temperature Tc and slightly the polarization values. The incorporation of praseodymium resulted in a variation in the permittivity and in the remanent polarization (2Pr). The polarization characteristics in the samples doping were different to Bi4Ti3O12.

Microstructure and ferroelectric properties of Nb-doped Bi4Ti3O12 thin films prepared by sol–gel method

The effects of Nb doping on the ferroelectric properties of Bi4Ti3O12 (BIT) thin films were investigated. Ferroelectric Nb-doped Bi4Ti3O12 (BTN) thin films were prepared by a sol–gel spin-coating method and annealed at several temperatures in an oxygen atmosphere. From analyzing X-ray diffraction patterns, it could be determined that a randomly oriented film was obtained by doping Nb ion into BIT thin film. The BTN film consisted of more disordered plate-like grains whereas the plate-like grains in the BIT film were more parallel to the substrate. The remanent polarization (2Pr) and coercive field (2Ec) of the BTN thin film that annealed at 700°C were about 39.8μC/cm2 and 136.7kV/cm at a sweep electric field of 175kV/cm. The pulse polarization (Psw−Pns) and the shape of the hysteresis loops did not change significantly before and after the 1.5×1010 switching cycles.

Ferroelectric properties and microstructures of Sm-doped Bi4Ti3O12 ceramics

Sm-doped bismuth titanate (Bi4−xSmxTi3O12 (BST)) ceramics were prepared by a conventional electroceramic technique and effects of Sm-doping on the ferroelectric properties of Bi4Ti3O12 (BIT) were investigated. XRD studies indicated that all of the BST ceramics consisted of single phase of a bismuth-layered structure corresponding to crystalline phase of BIT. SEM micrographs showed randomly oriented and plate-like morphology. For the BST ceramic with x=0.8, Sm-doping resulted in a large remanent polarization (Pr) of 16μC/cm2, a low-coercive field (Ec) of 70KV/cm and a low Curie temperature of 475°C.

Dielectric and ferroelectric properties ofBi4Ti3O12 ceramics produced by a laser sintering method

This work reports the synthesis and electrical characterization ofBi4Ti3O12 ceramics produced successfully by a new method based on aCO2 laser sintering process. The structural and microstructural characterizations revealed thatthis method is able to produce sintered samples with high quality, free from secondaryphases and with density as high as 98% of the theoretical one. Additionally, ferroelectricand dielectric investigations also revealed excellent values for the polarization anddielectric constant, respectively, thus showing the viability of the proposed method.

Sol-Gel Derived Nd-Substituted Bi4Ti3O12 Thin Film and Its Electrical Properties

Effect of neodymium substitution on the ferroelectric properties of Bi4Ti3O12 was investigated using a sol-gel method. We successfully synthesized 10 wt% homogeneous sol-gel solution of Bi3.15Nd0.85Ti3O12 (BNT) with 12% excess bismuth content. BNT thin films were fabricated on the Pt/TiO2/SiO2/Si substrates by spin coating deposition technique. The final film composition of Bi3.15Nd0.85Ti3O12 was obtained by Rutherford backscattering spectroscopy analysis. The 200-nm-thick BNT films have a strong (117) XRD peak with suppressed (00l) peaks due to the substitution of Nd, and the remanent polarization (2Pr) value of Pt/BNT/Pt structure is 48 μ C/cm2 at 7V, which is significantly greater than those of other ferroelectric thin films such as PZT, SBT and BLT.

Large remanent polarization of vanadium-doped Bi4Ti3O12

Effects of vanadium doping on the ferroelectric properties of Bi4Ti3O12 were investigated using dense ceramics. The incorporation of vanadium resulted in a large remanent polarization (2Pr) of over 40 μC/cm2 without sacrificing other physical properties, and the polarization characteristics were shown to be superior to SrBi2Ta2O9 and Sr0.8Bi2.2Ta2O9. In addition, dense ceramics of vanadium-doped Bi4Ti3O12 could be obtained by sintering at temperatures 100–200 °C lower than those for the SrBi2Ta2O9 system.

Synthesis and Characterization of Bi4Ti3O12 Thin Films by Sol-Gel Processing

Stoichiometric Bi4Ti3O12 thin films were prepared by sol-gel processing. This paper discusses the synthesis of polymerizable solutions containing Bi and Ti, and characterization of the resulting Bi4Ti3O12 thin films. The formation of metallic alkoxide and acetate alkoxide are indispensable, soluble precursors for these multicomponent systems. The double alkoxide was prepared by allowing Bi acetate to react with Ti alkoxides. The development of the polymerizable solution system containing Bi and Ti required choosing appropriate solvents and metallo-organic sources for the two components. Bismuth acetate, titanium methoxyethoxide and the solvents 2-methoxyethanol and glacial acetic acid were selected based on their successful use in a number of related systems. Thin films of Bi4Ti3O12 were obtained onto platinized Si substrates by spin casting, followed by heat-treated at 700°C. These films were later characterized by X-ray diffraction and SEM. The measured dielectric and ferroelectric properties of Bi4Ti3O12 were as follows: dielectric constant 120, dielectric loss 0.5%, remanent polarization Pr=4 µC/cm2, coercive field Ec=1.8 kV/cm.