Doped Barium Strontium Titanate Research Articles

Co-relation between Rietveld analysis, dielectric studies and impedance spectroscopy of the Ba1−xSrxTiO3 ceramics

Barium strontium titanate (BST), with varying Sr doping levels (x = 0, 0.05, 0.075, 0.1, 0.15, 0.3), was successfully synthesized using the solid-state reaction technique. The aim was to investigate the microstructural, dielectric, and impedance properties as Sr doping increases. X-ray diffraction analysis revealed a tetragonal phase structure for these materials, belonging to the P4mm space group, confirmed via Rietveld refinement using the Fullprof suite. SEM analysis indicated the decrement in grain sizes ranging from 0.198 to 0.0582 μm as doping concentration increases. The temperature and frequency dependencies of the dielectric constant were examined, with the Curie temperature observed in the range of 295 to 351 K with decreasing trend with substitution of strontium in pure barium titanate, showing an increase in dielectric constant with rising temperatures and non-relaxor behavior. P–E loops of BST samples illustrated bulk ferroelectric behavior, with maximum values of retentivity and coercivity reaching 1.56 and 13.97, respectively, in the highly doped BST sample. Various analytical techniques, including Nyquist plots, real and imaginary components of impedance, conductivity measurements, modulus formalism, and determination of charge carrier activation energy, were employed to elucidate the relationships between microstructure and electrical properties. Temperature-dependent resistivity demonstrated the negative temperature coefficient of resistance (NTCR) behavior in Sr-doped barium titanate. Impedance studies revealed semicircular arcs in Nyquist plots, indicating contributions from both grains and grain boundaries. The formation of well-defined grains in the BST samples was further confirmed through modulus spectroscopy.

Multielement Doped Barium Strontium Titanate Nanomaterials as Capacitors

Due to the growing demand of energy and wastage of energy, there exists an interest of storing energy so that it could be utilized efficiently. Capacitors are materials designed for such an application. Ferroelectric materials are known for their application as capacitors. Of such materials, perovskites are the preferable classes of materials that have been used as capacitors. Barium strontium titanate nanomaterial is a member of perovskites which encompasses a smaller dielectric loss, elevated dielectric constant, and good thermal stability. Research studies also clarified that incorporating dopants into a barium strontium titanate nanomaterial of high dielectric materials including metal/metal oxides enhances their efficiency and effectiveness. Moreover, multielement doping or codoping has shown better dielectric properties as compared to the unidoping of BST. In this review, barium strontium titanate capacitors codoped with more than one metal/metal oxides have been studied most of which have shown that the codoped barium strontium titanate materials possess improved and sufficient dielectric properties to be utilized as capacitors. We believe that this work will have of its own contribution on understanding the doped barium strontium titanate nanomaterial by clarifying the most probable and detail reasons behind the enhancement of dielectric properties of codoped barium strontium titanate nanomaterials.

Enhancement of antibacterial and cytocompatibility of Ti by Zn-doped BST coatings

Titanium (Ti) is a material commonly used in orthopedic implants. However, the lack of antimicrobial properties limits its application in implants. Herein, we constructed zinc (Zn)-doped barium strontium titanate (BST) films on Ti. The results show that the Zn-doped BST films can effectively improve the antibacterial ability of Ti substrates, which presents potential applications in bone repair.

Comparison of structural and dielectric properties of doped (M, R and A) barium strontium Titanate: Review

Barium Strontium Titanate is lead -free, environment friendly compound having high dielectric constant, high dielectric tunability and low dielectric loss which make this perovskite material applicable for various industrial, electronic and microwave tunable device. Recent development in Barium Strontium Titanate by doping modification of (Alkali metal, Transition and Rare earth metal) are reviewed. The A site doping, B site doping and both site co-doping modification are analysed and summarized respectively. By using multiple manufacturing techniques, including the conventional method and sol–gel, the comparison of the dielectric and microstructure properties of barium strontium titanate with different dopants is critically examined. Out of these dopants, Transition metal doped Barium Strontium Titanate show more suitable properties for applications like storage capacitors and phase shifters etc. BST ceramics with transition metal doping shows low dielectric loss and high dielectric constant suitable for DRAM cell capacitor as well as for tunable antennas having large frequency domain, as well as for microwaves devices.

Spin and valence variation in cobalt doped barium strontium titanate ceramics

Spin fluctuation and spin variation phenomena with comparative crystal field energy and Hund energy for Co doped barium strontium titanate.

Microwave-Assisted Synthesized Gadolinium Doped Barium Strontium Titanate Nanostructures: Structural and Optical Properties for DSSC Applications

Gadolinium (Gd) doped barium strontium titanate (BST) was prepared using the microwave-assisted solid-state reaction method for dye sensitized solar cell (DSSC) applications. The optical properties and the structural analysis of the prepared samples reveal the optical band gap and the morphology. The XRD pattern of the annealed samples confirms the polycrystalline nature with the cubic crystal structure. When the dopant is added, the bandgap increases slightly from 3.11 to 3.27 eV. The J-V characteristics of DSSCs prepared with pure and doped BST were investigated. The efficiency of the DSSCs remained constant and there is a slight increase in the Jsc for highly doped samples under 1-sun illumination. Gadolinium doped barium strontium titanate shows variation in the J-V characteristics and could be a potential candidate for the solar photovoltaic applications.

Synthesis and characterizations of metal ions doped barium strontium titanate (BST) nanomaterials for photocatalytic and electrical applications: A mini review

AbstractThe ferroelectric barium strontium titanate (Ba1-xSrxTiO3) is a homogeneous solid solution prepared from the mixture of barium titanate (BaTiO3), strontium titanate (SrTiO3) and titanium (IV) isopropoxide. Barium strontium titanate (BST) nanomaterials with improved permittivity and dielectric properties due to their nano-properties have attracted great interest for extensive and versatile applications as super capacitors, dielectrics, ceramics and catalysts. Introduction of metal ion dopants into the parent system of BST significantly alters its structural, morphological, electrical, optical and dielectric characteristics. This review is aimed at addressing synthesis, characterization methods, photocatalytic and electrical applications of metal ions doped BST nanomaterials. The effect of doping BST, through metal ions, on its properties and application with most probable reasons have been thoroughly discussed.

Nanostructured Cobalt Doped Barium Strontium Titanate Thin Films with Potential in CO2 Detection.

In this work, (Ba0.75Sr0.25) (Ti0.95Co0.05) O3 perovskite nanostructured material, denoted subsequently as Co-doped BaSrTiO3, was synthesized in a one-step process in hydrothermal conditions. The obtained powder was heat-treated at 800 °C and 1000 °C, respectively, in order to study nanostructured powder behavior during thermal treatment. The Co-doped BaSrTiO3 powder was pressed into pellets of 5.08 cm (2 inches) then used for thin film deposition onto commercial Al2O3 substrates by RF sputtering method. The microstructural, thermal, and gas sensing properties were investigated. The electrical and thermodynamic characterization allowed the evaluation of thermodynamic stability and the correlation of structural features with the sensing properties revealed under real operating conditions. The sensing behavior with respect to the temperature range between 23 and 400 °C, for a fixed CO2 concentration of 3000 ppm, highlighted specific differences between Co-doped BaSrTiO3 treated at 800 °C compared to that treated at 1000 °C. The influence of the relative humidity level on the CO2 concentrations and the other potential interfering gases was also analyzed. Two possible mechanisms for CO2 interaction were then proposed. The simple and low-cost technology, together with the high sensitivity when operating at room temperature corresponding to low power consumption, suggests that Co-doped BaSrTiO3 has a good potential for use in developing portable CO2 detectors.

Optical and structural properties of tungsten-doped barium strontium titanate

The effect of variation in the tungsten content on the tungsten doped barium strontium titanate for their use in DSSC is studied. Samples were prepared by solid state reaction for the dopant variation of x = 0, 0.2, 0.4 and 0.6. The characterization of optical properties was performed by UV–Vis spectrometer by diffused reflectance Method to find the optical band gab and microstructural characterization was performed by X-ray diffraction (XRD) and the FESEM reveals the morphology of the samples prepared. Tungsten doped barium strontium titanate shows good variation in the morphology and the structure.

Structural, optical and electrical studies on zinc doped barium strontium titanate as photo-anode for DSSC device

Nano crystalline Barium strontium titanate (BST) and zinc doped barium strontium titanate (BSZT) with general formula Ba0.5−xSr0.5ZnxTiO3 (x = 0, 0.05, 0.10 and 0.15) were synthesized by modified sol–gel method. The synthesized nano crystalline powders were characterized using XRD, UV-DRS, FTIR, FESEM, particle size analysis (PSA) and I-V Photovoltaic tests. The structural, optical and electrical properties of the nano crystalline powders were explored. XRD results confirm the formation of cubic structure and their average crystallite size is estimated. The electrical investigation indicates that the addition of Zn to BST nanoparticles improves the conductivity of the sample, hence it could be potential candidate for the solar cells.

Morphology characterization and dielectric performances of Ce-doped barium strontium titanate powders prepared by modified citrate method

ABSTRACTCitrate acid (CA), ethylene glycol (EG), and absolute ethyl alcohol (AEA) were combined to synthesize 0∼5% mol cerium doped barium strontium titanate (Ce-BST) powders, and the morphology characterization and dielectric performances of the powders were studied. X-ray diffraction (XRD) shows that the powders have ABO3 perovskite structures with no secondary phase until ≥4% mol because AEA avoids the formation of cerium hydroxide caused by the hydrolyzation of Ce3+ ions, and Ce3+ ions enter into lattices to make lattice parameters increase. Scanning electronic microscope (SEM) reveals that Ce3+ ions affect grain growth and refine grain size with uniform grain size of about 100 nm at 2 mol%. Permittivity and loss tangent of the doped powders are decreased, where 2 mol% corresponds to the optimum dielectric properties with permittivity of 58 and loss of 0.007 at 1 GHz, which can meet the requirements in many applications like microwave devices. The relation between dielectric properties and Ce doping is also discussed.

Electrical relaxation and conduction mechanisms in iron doped barium strontium titanate

Polycrystalline Ba0.7Sr0.3Ti(1−x)FexO3 (x = 0.1) (BSTF) ceramics, synthesized via solid-state reaction route were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance spectroscopy (CIS). The Rietveld refinement of the XRD data confirmed the presence of tetragonal and cubic phases in the prepared sample. The SEM image revealed that the sample has well distributed grains along with some degree of agglomerations. The electrical behaviour of the BSTF ceramic has been studied by complex impedance spectroscopy (CIS) as a function of frequency (1Hz to 1MHz) at different temperatures (RT to 700K). Two semicircular arcs observed in the Cole-Cole plot confirm the contribution from the grain and grain boundary in overall impedance. Both the electrical as well as ac conduction phenomena take place via correlated barrier hopping (CBH) authenticated by detailed complex modulus analysis and ac fitted conductivity respectively. The values of activation energies calculated from electrical impedance, modulus, and conductivity data clearly reveal that the relaxation and conduction processes in BSTF ceramic are induced by doubly ionized oxygen vacancies.

Optical properties of Cu and Ru doped BST thin films with additive glycerol and MESA surfactant

In this paper, barium strontium titanate (BST) thin films were deposited by chemical solution deposition (CSD) with addition glycerol and methyl ester sulfonic acid (MESA) surfactant as additive materials. The effect of variation spinning speed (5500 and 8000 rpm), different dopant (Cu and Ru dopants), and also additive materials on optical properties were studied by Spectrophotometer Vis-NIR. As a result, BST thin films with additive MESA have higher absorbance and similar spectrum pattern than additive glycerol. Generally, BST thin films with MESA surfactant had band gap smaller than glycerol of BST thin films. Absorption and extinction coefficient of BST with glycerol were observed and we reported Ru doped BST at spinning speed 5500 rpm had higher value than other films. On other hand, Cu doped BST at 8000 rpm had absorption and extinction coefficient higher than other films.

Preparation and Microstructural Characterization of Niobium Pentoxide Doped Barium Strontium Titanate Glass and Glass-Ceramics

ABSTRACT(Ba0.2Sr0.8)TiO3-2SiO2-B2O3-K2O compositions based glass and glass-ceramics with and without 0.1 mol% Nb2O5 were prepared by melt-quench method. XRD and FTIR spectra reveal the formation of amorphous structure and the presence of stretching and deformation vibration bonds of B-O-Si linkage and Si-O-Si bridges, respectively. Differential scanning calorimetry (DSC) of the glass sample shows that onset of crystallization for (Ba0.2Sr0.8)TiO3 phase occurs between ∼750o and 800°C. XRD confirms the formation of (Ba0.256Sr0.744)TiO3 as major phase upon controlled crystallization of the glass samples at ∼750o-800°C for 3 h with rutile and SiO2 as minor phase(s). Quantitative phase analysis using structural Rietveld refinement of the powder XRD patterns shows that 0.1 mol% Nb2O5 addition in the [(Ba0.2Sr0.8)O.TiO2]-[2SiO2-B2O3]- [K2O] glass-ceramic system promotes the formation of Ba0.256Sr0.744TiO3 phase and suppresses the amount of rutile or TiO2 compared to undoped glass-ceramic system. SEM-EDS microstructural analysis of undoped glass-ceramic illustrates the formation of micrometer size flower-like Ba0.256Sr0.744TiO3, and needle-shape TiO2 crystals. However, addition of 0.1 mol% Nb2O5 changes the crystals to irregular shape. Results from the dielectric measurements performed from room temperature to 250°C show that dielectric constant increases slightly with the addition of 0.1 mol% Nb2O5 compared to undoped glass-ceramic samples.

Effect of cerium doped concentration on grain growing modes of BST powder

ABSTRACTCerium (Ce) doped barium strontium titanate (Ce-BST) powder was prepared by sol-gel method, and the effect of Ce doped concentration on growing modes of grains of the Ce-BST powder was studied. X-ray diffraction (XRD) reveals that all Ce-BST powders show cubic perovskite structures. It can be found that increasing Ce doped concentration corresponds to decreasing lattice parameter until the doped concentration increases to 3% mol ratio, and then the continuingly increasing doped concentration corresponds to increasing lattice parameter. Scanning electron microscopy (SEM) exhibits that all powders are composed of nano-grains, but the growing modes of the grains strongly depend on the doped concentration. When doped concentration is not more than 1% mol ratio, the grains show globular growth; when the doped concentration is not less than 3% mol ratio, the grains show layered growth; when the doped concentration ranges from 1% mol ratio to 3% mol ratio, columnar grains appear in the globular powders. Also, the dielectric properties of the powders are presented and the related mechanisms are discussed.

Structural, magnetic and electronic properties of iron doped barium strontium titanate

Very less known magnetic and the electronic properties of iron doped barium strontium titanate are reported.

Structural and dielectric properties of iron doped barium strontium titanate for storage applications

Barium strontium titanate (BST) and iron doped barium strontium titanate (BSTF) ceramics with general formula (Ba0.5Sr0.5Ti1−yFeyO3) and different iron (Fe) contents were prepared by slow rate injection sol–gel technique. The phase analysis, morphology and dielectric properties of BSTFs were investigated. The phase analysis was carried out using XRD which revealed the crystallization of BSTF in perovskite structure with single phase. The Fe doped BST peaks shifted toward higher angles and the calculated crystallite size was 19 nm on average. The BSTF morphology was studied using TEM which showed that the particle size was affected by Fe content. The average particle size was found to be 37 nm for (Ba0.5Sr0.5Ti1−yFeyO3) with Fe concentration of (y = 0.01, 0.05 and 0.1) calcined at (600, 800 and 1000 °C). The dielectric measurements were carried out using impedance analyzer at room temperature as a function of frequency in the range of 10 Hz to 1 MHz. The dielectric constant and dielectric loss of the 1 mol% Fe-doped Ba0.5Sr0.5TiO3 at 1 kHz were 1453.69 and 0.0063, respectively. The BSTF ceramics with high dielectric constant and low dielectric loss were obtained for the application DRAM cell capacitor.

Structural and magnetic properties of iron doped barium strontium titanate ceramic synthesised using slow injection sol–gel technique

Iron doped Ba0.6Sr0.4TiO3 (Ba0.6Sr0.4Ti1 − xFexO3) ceramics have been synthesised using slow injection sol–gel technique and calcined at 1000°C. The dopant concentration and processing control conditions were varied in order to investigate the structural and magnetic saturation of iron doped barium strontium titanate materials (BSTF). X-ray diffraction analysis revealed that these materials crystallised in perovskite structure. Scanning electron microscopy analysis showed that the grains were of irregular shapes with the size in the range of 34–106nm. Elemental analysis by energy dispersive spectroscopy confirmed that the prepared BSTF materials had the correct stoichiometry. On the other hand, the magnetic saturation Ms has the highest value of 2.4336 emu g− 1 at doping level of x = 0.2.

Preparation and Dielectric Properties of Ce-Doped Barium Strontium Titanate Nano-Powders

Citric acid and ethanol are attempted to prepare cerium doped barium strontium titanate (Ce-BST) nano-powders, and the structure and dielectric properties of the powders were studied. X-ray diffraction (XRD) shows that the powders are ABO3 cubic perovskite structure almost with no second phase. Scanning electronic microscope (SEM) reveals that the powders calcined at 850°C contain many spherical and loose soft conglobations composed of uniform grains with average size less than 100 nm. The powders display excellent dielectric properties with particularly low dielectric loss tangent of 0.002 due to Ce doping. The optimum dielectric properties were achieved at 900°C with dielectric constant of 63.2 and dielectric loss of 0.003 at 1GHz. The powders can be fully satisfied the requirements in many applications like microwave devices. The effect of the calcination temperature and related mechanisms are discussed.

Structural, dielectric and electrical properties of Zn doped Ba0.8Sr0.2TiO3

Zn doped barium–strontium–titanate Ba0.8Sr0.2−xZnxTiO3 ceramics with x=0, x=0.03 and x=0.05 were synthetized by solid state reaction technique. Structural, dielectric and electrical properties of these compounds were investigated. For all samples, X-ray diffraction analysis revealed a tetragonal symmetry P4mm. It is found that c/a parameters ratio increase with increasing Zn content. Using impedance spectroscopy technique, the dielectric and electrical properties were obtained from the conductance and capacitance measurements over a wide frequency (40Hz–1MHz) and temperature (80–550K) ranges. For all compositions, the dielectric study revealed a classical ferroelectric behavior. For undoped material, electrical conductivity analysis shows a dispersion regime in the whole explored frequency range. For Zn doped compounds, the conductivity follows a Jonscher universal low.