Properties Of Sodium Bismuth Titanate Research Articles

Study on the properties of sodium bismuth titanate coating prepared by supersonic plasma spraying

In order to realize the preparation of environmentally friendly piezoelectric ceramic coatings on the surface of metallic materials, sodium bismuth titanate (Bi0.5Na0.5TiO3, BNT) ceramic coatings were prepared by supersonic plasma spraying. The surface morphology, cross-sectional morphology, phase structure, and elemental valence variations of the BNT coating were examined, as well as the dielectric and ferroelectric properties of the BNT coating. The results show that the coating has a good quality and a single perovskite structure. The dielectric constant was stable at about 425 and the dielectric loss was stable at about 0.06 when the test frequency reached 200 kHz. The coating exhibits good hysteresis lines under different applied electric fields. When the applied electric field was 40 kV/cm, the remnant polarization value of the prepared coating was 11.47 µC/cm2. It can be seen that the BNT piezoelectric coating prepared by supersonic plasma spraying has good ferroelectric and dielectric properties, which lays a solid foundation for in-situ monitoring of environmentally friendly lead-free BNT piezoelectric coating.

Structural, optical, electrical, and dielectric relaxation properties of rare earth containing sodium bismuth titanate [formula omitted] perovskite: Effect of ionic radius

The main focus of this work is to study the effect of the ionic radius of different rare earth dopant cations RE3+ (RE = La, Sm, Dy, and Ho) on structural and various physical properties of sodium bismuth titanate (Na0.5Bi0.5TiO3, NBT) based perovskite nanomaterials. The X-ray diffraction data indicate the successful formation of the rhombohedral phase (space group R3c) of NBT nano perovskite incorporated with various rare earth ions in Bi-site. The lattice parameters were found to increase linearly with the ionic radius of the dopant cation. The ionic radii and atomic mass of rare earth dopants appear to be essential factors in the grain growth of the prepared compositions. The grain growth results in better crystallinity of the sample by reducing the microstrain with the increase of dopant ionic radius. Field emission scanning electron microscopy and energy-dispersive X-ray spectra confirm the prepared compositions' phase purity and stoichiometry. The UV–Vis spectra reveal that La-doped NBT composition exhibits the lowest optical band gap, which unfolds the application of NBT-based perovskite as photoactive material. The ac conductivity and complex impedance spectra unveil that the composition with the largest ionic radius, i.e., La-doped NBT compound, exhibits the highest dc and bulk conductivity with the lowest activation energy. The frequency-dependent dielectric data follows Havriliak–Negami (HN) formalism and non-Debye type relaxation phenomena. Results also indicate that La-doped NBT composition exhibits the highest dielectric strength value. Thus, this study first elaborates that the increasing ionic radius of the rare earth dopant cation in the Bi-site of NBT perovskite improves its microstructural, optical, and electrical properties.

Effect of conventional and microwave sintering on microstructure and ferroelectric properties of sodium bismuth titanate (NBT) perovskite ceramics

Microstructure and ferroelectric properties of Na0.5Bi0.5TiO3 ceramic prepared by SSR method with different sintering route were investigated to study the effect of microwave sintering on the energy storage properties. Rietveld refinement of XRD data showed trigonal (Rhombohedral) single phase structure with R3C space group and SEM micrographs showed the dense microstructure with little surface segregation and most uniform grainsize distribution found for 10 min. microwave sintering. The slim shape P-E loop confirms low energy losses in all studied samples. Microwave sintering found useful to improve ferroelectric properties of studied samples and good optimization of ferroelectric parameters achieved for 10 min. microwave sintering in present studied system.

Experimental and simulation studies on dielectric, AC resistivity and electromechanical properties of sodium bismuth titanate based ceramics

The experimental and simulation of dielectric, AC resistivity and dielectric resonance and anti-resonance data on (Na0.5Bi0.5)(NdxTi1-2xNbx)O3] ceramics were carried out using modified Lorentz equations as proposed by us instead of well know and generally applied laws like Arrhenius law and formulas on piezoelectricity to obtain activation energy, relaxation time, piezoelectric charge constant and voltage constant directly from the experimental data. The piezoelectric charge constant (d33) evaluated from the modeling are 864.64 p.m/V and 122.40 p.m/V; whereas the piezoelectric voltage constant (g33) are 10.88 p.m2/C and 8.55 p.m2/C for x = 0.0125 and 0.025 ceramic samples, respectively.

Structural and optical properties of (Y3+, Tb3+)-codoped sodium bismuth titanate nanoparticles

The present study investigates the effect of (yttrium, terbium) ions codoping on structural and optical properties of sodium bismuth titanate (Na0.5Bi0.5TiO3 or NBT) with the possible practical application as a multi-luminescence material in optoelectronic devices such as light-emitting diodes. The polycrystalline samples of Na0.5(Y/TbxBi1-x)0.5TiO3 (x = 0.00, 0.04, 0.06, and 0.08) were synthesized using solid-state reaction (mixed oxide) technique. Stoichiometric amounts of metal compounds (Na2CO3, Y2O3, Tb4O7, Bi2O3, and TiO2) were mixed via ball milling at 250 rpm for 2 h, and the ground powders were calcined at 700 °C for 2 h. The powders were pressed under uniaxial pressure of 6.87 MPa to obtain green pellets, which were later sintered at 1,000 °C for 2 h to obtain the Na0.5(Y/TbxBi1-x)0.5TiO3 samples. X-ray diffraction analysis suggests that the perovskite phase is established for all (Y3+, Tb3+)-codoped NBT compositions (x = 0.00–0.08). The presence of NBT functional groups was confirmed by Fourier transform infrared spectroscopy. Raman spectra indicate that (Y3+, Tb3+) ions induce minor changes to the crystal lattice structure, with no disturbance to the long-range order. X-ray photoelectron spectroscopy results reveal the presence of all the constituent elements in the NBT samples. Scanning electron microscopy confirms the polycrystalline nature of the samples with uniform distribution of multifacetted or nearly spherical grain structures. Transmission electron microscopy and selected area electron diffraction (SAED) images show the presence of nanocrystals in the samples. Ultraviolet diffuse reflectance spectroscopy (UV-DRS) and photoluminescence results illustrate that Na0.5(Y/TbxBi1-x)0.5TiO3 possess wider optical energy band gap (Eg = 3.23–3.27 eV) with promising luminescence applications in the optoelectronic industry.

Effect of synthesis route on the structural and electrical properties of sodium bismuth titanate: A comparative study of solid-state and polyol mediated synthesis

Sodium bismuth titanate (NBT) was synthesized through two different synthesis methods: solid-state reaction (SS) and polyol mediated synthesis (PM). The effect of synthesis route on the structural and electrical properties of NBT system has been investigated. Polyol mediated synthesize NBT sample result in single-phase at relatively lower temperature than of prepared via the solid-state reaction method. The Rietveld refinement of the XRD data confirms that both the sample crystallizes in the rhombohedral perovskite phase with R3c space group. The morphological properties indicate that the grain size of the polyol method processed sample is smaller and slightly agglomerated than the one prepared via solid-state route. Impedance results reveal enhanced bulk conductivity for PM synthesized samples as compared to SS route. Thus, the polyol mediated synthesis may be a better approach for the synthesis of NBT samples. Furthermore, a correlation between the structural and electrical properties for both methods synthesized samples have been discussed to explain the conductivity behaviour.

Tailoring the electrical and structural properties of sodium bismuth titanate with sintering temperature

Abstract Na0.5Bi0.5TiO3 (NBT) has attracted the attention of researchers because of the utilization of its accepter doped compositions as electrolyte materials in Solid Oxide Fuel Cells (SOFCs). This study reports the consequences of sintering temperature on the structural and electrical properties of sodium bismuth titanate (NBT). The NBT sample was synthesized using solid-state reaction route and sintered at two different temperatures. Both samples were characterized by X-ray diffraction, scanning electron microscopy and impedance spectroscopy techniques. X-ray diffractograms and its Rietveld refinement confirm the rhombohedral R3c symmetry with perovskite structures. SEM micrographs reveal grain growth with the rise in the sintering temperature. Impedance results in the frequency range of 24 Hz–1 MHz & temperature range of 500–700 °C suggest the increase in the conductivity with the sintering temperature. Moreover, the oxide ion migration pathway and energy barrier were analyzed using bond valance (BVE) analysis technique.

Structural, optical and enhanced electrical properties of vanadium alloyed sodium bismuth titanate solid solution synthesized by a chemical-mechanical hybrid method

This work focuses on the effect of V2O5 addition on the structural, optical and electrical properties of Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) nanomaterials, for its possible application as an electrolyte in SOFC. Pure Na0.5Bi0.5TiO3 (NBT) material has been synthesized using citrate auto-ignition method and V2O5 has been reinforced in the perovskite structure by mechanical alloying. X-ray diffraction analysis confirms the formation of the rhombohedral phase of NBT perovskite with space group R3c. Rietveld Analysis indicates the presence of insoluble minor V2O5 phase in the 20% milled composition. The values of lattice parameters, particle size, and the microstrain have been found to vary with V2O5 addition. The presence of different bonds has been confirmed from FT-IR analysis. It has been found that the vanadium incorporation can tune the optical bandgap of the material. The real part of complex ac conductivity has been found to follow universal Jonscher power law. The variation in conductivity is correlated with the structural changes due to V2O5 addition. The highest conductivity achieved was 1.0143 × 10−4 at 400 °C for the 15% doped composition. The conductivity mechanism has been explained by Mott’s variable range hopping model.

Strain-induced effects in the electronic and optical properties of Na0.5Bi0.5TiO3: An ab-initio study

The ground-state properties of sodium bismuth titanate (Na0.5Bi0.5TiO3-NBT) are studied using first-principles calculations based on density functional theory (DFT). The electronic band structure reveals that the direct and indirect band gaps are rather close (within ∼0.07 eV of each other). This has implications for resolving the existing variance in reports regarding the nature of band gap in NBT and supports He et al.’s recent experiment-based inference. We also report hydrostatic strain-induced (ε = -0.02 (compression) to 0.02 (tension)) band gap variation and demonstrate electron/hole effective mass (me*/ mh*) tunability in NBT. Importantly in compression, NBT has both direct and indirect band gaps that are rather close; but in tension, it is clearly an indirect band gap system. We identify conditions (ε = 0, -0.01) wherein me* > mh*; this is known to be for a predictive measure for transparent p-type conducting oxides. For all the optical constants, we find a significant blue-shift in their spectra under compressive strains and a nominal red-shift in their values under tensile strains. Compression is pointed to as a rather facile means to tune the optical properties of NBT. Our results offer pointers that can make NBT relevant for applications involving light-harvesting, charge separation, and charge storage.

Structural and electrical properties of sodium bismuth titanate based 0–3 composite lead-free ferroelectric thick films

Future piezo-(ferro-)electric devices, in particularly the transducers with the miniaturized size require materials with thickness in micrometer scale, which limit the utilization of bulk materials due to the difficulty of thinning. Modified composite sol-gel methods turns out to be a powerful approach to fabricate thick piezo-(ferro-)electric oxide films with thicknesses of several micrometers, which satisfy the requirements of devices particularly transducers. We report the preparation of the lead-free (Bi0·5Na0.5)1-xBaxTiO3-Bi0.5Na0·5TiO3 (BNBTx%-BNT, x = 0, 0.05, 0.06, 0.07) 0–3 composite ferroelectric thick films using a modified composite sol-gel technique. The impacts of the composition of the powders and the thickness of films on the structural and electrical properties of BNBTx%-BNT composite thick films have been in-depth investigated. The dielectric, ferroelectric and piezoelectric properties of the films strongly depend on the composition of the ferroelectric powders. The most excellent electrical properties are found in BNBT6-BNT films, which have the phase at morphotropic phase boundary. These results indicate that the BNBTx%-BNT 0–3 composite thick films are a highly promising lead-free piezoelectric material for piezo-(ferro-)electric device applications like high-frequency transducers.

Structural and electrical properties of sodium bismuth titanate (Na0.5Bi0.5TiO3) thin films optimized using the Taguchi approach

Controllable Pulsed Laser Deposition (PLD) parameters have been optimized to grow sodium bismuth titanate (Na0.5Bi0.5TiO3) (NBT) thin films. Target to substrate distance, background gas pressure, substrate temperature, laser fluence, laser rate of repetition, annealing time and NBT targets with and without excess Bi have been chosen as the parameters using a Taguchi L18 orthogonal array. Taguchi's Signal-to-Noise (S/N) ratios and analysis of variance (ANOVA) tools highlight the relevance of each parameter, and also yield the optimal setting of the parameters. The dominant parameters affecting dielectric properties are oxygen gas pressure and substrate temperature, whereas the distance between target to substrate and laser fluence appear as significant parameters. Fine tuning experiments and a subsequent verification experiment using the dominant and significant parameters result in the best values for the dielectric constant of 735, dielectric loss of 0.07 at 1kHz and remnant polarization of 21.42µC/cm2.

Influences of compressive stress and aging on dielectric properties of sodium bismuth titanate ceramics

The influences of compressive stress and aging on dielectric properties of undoped and Fe-doped sodium bismuth titanate (NBT) ceramics were investigated. The dielectric properties were decreased significantly with the compressive stress applied parallel to the electric field direction, while the changes were reversed with the stress applied perpendicularly. In addition, lower changes of the dielectric properties with stress were observed in Fe-NBT ceramics, likely caused by an enhanced relaxor characteristic with the acceptor doping, which also reduced the aging rate in the ceramics. Finally, the aging behavior of the NBT and Fe-NBT ceramics followed the slightly stretched exponential law, and the aging rate in both ceramics was found to decrease with frequency, a result of the pinning of the polarization components. These observations clearly confirmed the role of the acceptor dopant in enhancing the relaxor ferroelectric characteristics in the NBT-based ceramics.