Properties Of Bi Research Articles

Effect of Starting Mn Precursor on the Structural and Ferroelectric Properties of BCT Based Solid Solutions

The effect of starting Mn precursor (0.01≤x ≤ 0.04) on the structural and ferroelectric properties of Ba0.96Ca0.04Ti(1−x)MnxO3 samples prepared using conventional solid state reaction route have been investigated. The XRD analysis shows that the samples possess tetragonal structure and are phase pure up to x = 0.02 independent of starting Mn precursor. The samples x = 0.03 and x = 0.04 shows the presence of an additional hexagonal phase. The concentration of additional phase increases with increasing x. The P-E loops were recorded at room temperature showing the ferroelectric behaviour of the samples.

Synthesis and properties of bi- and tricyclic 1,3-thiazoline/thiazolidine assemblies linked by an exocyclic С=С double bond

This review provides a generalized and systematized analysis of literature data from the last 15 years regarding the methods of synthesis and properties of bi- and tricyclic assemblies constructed from 1,3-thiazolidine/thiazoline rings that are linked by an exocyclic С=С double bond. Examples of such assemblies which are of interest as biologically active compounds, sensitizing dyes for solar cells, and semiconductors are considered in details. The literature data have been arranged according to the types of chemical structures.

Temperature-dependent structure, dielectric properties of Bi0.95Ba0.05Fe0.95Ti0.05O1.3

The temperature-dependent structure and dielectric properties of Bi[Formula: see text]Ba[Formula: see text]Fe[Formula: see text] Ti[Formula: see text]O3 ceramic are studied systematically. At the temperature range of 25–800[Formula: see text]C, the cell parameters are increasing, this indicates its distorted rhombohedral [Formula: see text]3[Formula: see text] structure. A structural phase transformation from rhombohedral [Formula: see text]3[Formula: see text] to cubic Pm3[Formula: see text] is observed at 850[Formula: see text]C. The thermal expansion coefficients in the temperature range 25–700[Formula: see text]C are calculated. Meanwhile, the temperature-dependent dielectric constant ([Formula: see text]) and dielectric loss ([Formula: see text][Formula: see text]) at different frequencies are measured. This work attempts to show the thermodynamic stability and the effect of charge defects on the electric properties for doped BiFeO3 ceramics.

Effects of sintering time on microstructure and electric properties of Ba0.7Sr0.3TiO3 ceramics

Ba0.7Sr0.3TiO3 ceramics has been synthesized by solid state reaction method. The effects of sintering time on microstructure and electric properties of Ba0.7Sr0.3TiO3 ceramics have been investigated. XRD patterns show that all ceramic samples are single tetragonal phase. The grain size increases with sintering time. Ba0.7Sr0.3TiO3 ceramics show obvious relaxor behavior because of its broadening dielectric peaks and frequency dispersion phenomenon. As sintering time increases, the Curie temperature does not change significantly and the diffuseness of the phase transition of Ba0.7Sr0.3TiO3 ceramics slightly enhances. Moreover, the remnant polarization and coercive field have no obvious changes with the increasing of sintering time.

Structural, magnetic, and photocatalytic properties in Bi0.83−xLa0.17YxFeO3 nanoparticles

In this research, polycrystalline BiFeO3 (BFO) and Bi0.83−xLa0.17YxFeO3 nanoparticles (BLYxFO NPs, x = 0.0, 0.05, 0.10, 0.15, and 0.20) were prepared by sol–gel route. The effect of La3+ and Y3+ co-doped ions on crystal structure, magnetic, and photocatalytic properties was reported. The Rietveld refinement of X-ray diffraction data confirms a consecutive structural phase transition of R3c–Pbam–pnma from BFO to BLY0.20FO compound. The investigation of field-emission scanning electron microscopy (FE-SEM) images indicated that the morphology and distribution of nanoparticles are almost uniform. The energy-dispersive X-ray (EDAX) analysis confirms the elemental concentration in BLYxFO NPs. All of BLYxFO NPs revealed the weak ferromagnetic behavior. The highest magnetic parameters occur in the vicinity of the R3c/Pbam phase boundary in sample with x = 0. The change of magnetic behavior from BFO to BLY0FO was discussed based on suppressing spiral cycloid spin structure and lattice distortion in rhombohedral phase. In compounds with orthorhombic structure, only lattice distortion can be affected magnetic behavior. The direct bandgap of all samples obtained from the UV–Vis diffuse reflectance spectra using Kabelka–Munk equation. The bandgap in BLYxFO NPs decreases with substituting La ion and then increases with increasing Y content. The photocatalytic activity of BFO and BLYxFO NPs is evaluated by the degradation of methyl orange in the presence of H2O2 at pH value 2 under visible light. The photocatalytic properties enhance with doping La in BFO. However, the photocatalytic activity dependence on Y concentration has a behavior more complicated and is strongly depending on crystal structure.

Improving Transport Properties of Bi-2223 Superconducting Tapes With the Optimization of Packing Atmosphere

Multifilamentary Bi2Sr2Ca2Cu3O10+δ (Bi-2223) high temperature superconducting tapes were fabricated by powder-in-tube process. During the precursor powder packing process, environment atmosphere was changed from pure oxygen to dry air and 7.5% O2 balanced with N2, with the oxygen partial pressure decreasing from 100% to 25% and 7.5%, respectively. The change of packing atmosphere obviously influenced the phase assemblage in the early stage of Bi-2223 phase formation process. Therefore, the chemical composition of obtained Bi-2223 phase as well as the content and distribution of secondary phases changed accordingly. Meanwhile, the changes of intergrain connections and the flux pinning properties were investigated based on the in-field critical current, $I_{c}$ – B measurements. Finally, attributed to the decreased oxygen partial pressure in packing atmosphere, the $I_{c}$ improvements of 25% at self-field and 0.6 T were obtained comparing with the tapes packed under pure oxygen. With further optimization of sintering process, the final $I_{c}$ of 116 A was achieved, which corresponded to the critical current density, $J_{c}$ of ∼21 kAcm−2.

Utilisation of methylcellulose as a shaping agent in the fabrication of Ba0.95Ca0.05Ce0.9Y0.1O3 proton-conducting ceramic membranes via the gelcasting method

The gelcasting method was used to form gastight Ba0.95Ca0.05Ce0.9Y0.1O3 samples proposed for use as proton-conducting electrolytes in solid oxide fuel cells. Methylcellulose was used as an environmentally friendly shaping agent for Ba0.95Ca0.05Ce0.9Y0.1O3 powder in an ethanol solution. Samples of Ba0.95Ca0.05Ce0.9Y0.1O3 were also prepared from the same powder via traditional isostatic pressing, as a reference for cast samples, and sintered in the same conditions. Comparative studies of the physicochemical properties of Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes, formed by means of these two methods and then sintered at 1550 °C for 2.5 h, were presented and discussed. Using the X-ray diffraction method, only the pure orthorhombic phase of BaCe0.9Y0.1O3 was detected in the Ba0.95Ca0.05Ce0.9Y0.1O3 powder, as well as in the Ba0.95Ca0.05Ce0.9Y0.1O3 sintered pellets formed via both gelcasting (A) and isostatic pressing (B). Thermal effects occurring during heating of methylcellulose, as well as ceramic Ba0.95Ca0.05Ce0.9Y0.1O3 powder, dried cast samples obtained from the prepared slurry, and sintered Ba0.95Ca0.05Ce0.9Y0.1O3 samples, were examined by differential scanning calorimetry, differential thermal analysis, thermogravimetric analysis, and evolved gas analysis of volatile products using a quadrupole mass spectrometer. The measurements were performed within the temperature range of 20–1200 °C in air. Based on dilatometric tests, it was found that the Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples exhibited slightly higher degree of sinterability than the 5CBCY samples obtained by isostatic pressing. In comparison with pressed pellets, higher values of total electrical conductivity in air or in a gas mixture of 5% H2 in Ar were also attained for Ba0.95Ca0.05Ce0.9Y0.1O3 cast samples. The Ba0.95Ca0.05Ce0.9Y0.1O3 samples were used to construct oxygen–hydrogen electrolytes for solid oxide fuel cells. The results of the electrochemical performance of solid oxide fuel cells with Ba0.95Ca0.05Ce0.9Y0.1O3 electrolytes were comparable to the data in the literature on BaCe0.9Y0.1O3 electrolytes. An electrochemical study of a Ba0.5Sr0.5Co0.8Fe0.2O3−δ|Ba0.95Ca0.05Ce0.9Y0.1O3 interface was also performed. Ba0.5Sr0.5Co0.8Fe0.2O3−δ appears to be a suitable cathode material for a Ba0.95Ca0.05Ce0.9Y0.1O3 electrolyte.

Influence of gamma irradiation exposure on structural, electrical and magnetic properties of Bi-2223 with Nb2O5 addition

The effects of gamma irradiation on the phase analysis, electrical and magnetic characteristics of Bi-2223 superconductors with Nb2O5 addition were systematically examined. The pristine and Nb-added Bi-2223 superconducting bulk samples were produced by the solid state reaction procedure using high purity oxide powders. The samples were exposed to 1, 5, and 10 kGy gamma ray. The effects of γ-irradiation on the phase analysis, electrical and physical properties of the samples were studied before and after irradiation. The phase formation and the lattice parameters of the samples were characterized by X-ray diffraction (XRD). The superconducting transition temperatures of the samples were determined from the resistance–temperature curve using the four point probe method. The current carrying capacities of all samples were estimated from the magnetization curve using the Bean critical state model.

Spontaneous Non-stoichiometry and Ordering in Degenerate but Gapped Transparent Conductors

Spontaneous Non-stoichiometry and Ordering in Degenerate but Gapped Transparent Conductors

Influences of Annealing on the Electrical Properties of Ba0,5Sr0,5TiO3

The research aims to investigate influences of annealing on the electrical properties of Ba0,5Sr0,5TiO3. Ba0,5Sr0,5TiO3 material which was annealed at 900°C for 1, 2 and 4 hours has better mechanical properties. It needs investigation for its electrical contribution, namely the correlation between grain and grain boundaries to values of resistance and capacitance. The changing of electrical properties was controlled by grain, grain boundary and the area between the sample and contact. The electrical properties of Ba0,5Sr0,5TiO3 were investigated by impedance spectroscopy in the room temperature. This method is able to separate the electrical and dielectric properties of the grain, grain boundary and the area between contact with the sample. ZsimpWin software was used to find out the equivalent electrical circuit, the resistance and capacitance value. It was observed that with the increase in annealing time the small grains resistance, the grain boundaries resistance, and the large grain capacitance value also increases. The resistance values of small grains and large grains were smaller than the grain boundaries resistance. The value of capacitance-resistance of the small grains and large grains were obtained values that tend to be smaller.

Influence of spin-state transition on structural and other physical properties in Ba0.5Sr0.5Co0.8Fe0.2O[formula omitted] ceramic

We explore, in detail, the remarkable influence of spin-state transition – low (S = 1/2) to high spin (S = 5/2) – on crystallographic, thermal, electrical, and mechanical properties in Ba0.5Sr0.5Co0.8Fe0.2O3−δ ceramic. The low to high spin transition takes place at T∗∼ 600 K with a rather broad transition zone of nearly 200 K. We find that the electrical resistivity, mechanical stiffness and toughness, thermal expansion coefficient, and the crystallographic structure exhibit clear anomalous features around T∗. The transition, however, appears to be isostructural Pm3̄m→Pm3̄m (cubic → cubic). Significant influence of spin-state transition on a variety of properties could have serious implications for several applications ranging from magnetic sensors to electrocatalysts to ion separation membranes.

Thickness-dependence of growth rate, dielectric response, and capacitance properties in Ba0.67Sr0.33TiO3/LaNiO3 hetero-structure thin films for film capacitor applications

This work reports the structure, growth rate, dielectric response, and capacitance properties of (100)-oriented Ba0.67Sr0.33TiO3 (BST)/LaNiO3 (LNO) hetero-structure thin films with varied BST layer thicknesses from 34 nm to 342 nm. The BST/LNO hetero-structure thin films were prepared by radiofrequency magnetron sputtering technique on Pt/SiO2/Si substrates. The XRD results showed that the compressive stress is relaxed at around 73 nm of BST layer, and above 119 nm of the BST layer thickness, the tensile stress has a significant effect on the crystal structure of the BST/LNO hetero-structure film. The growth rate of the BST films was thickness-dependent which was strongly related to the minimization of the strain energy. The dielectric constant of BST layer with the compressive stress increase from 177 to 2640 with the increase of BST layer thickness. The BST layer with the tensile stress showed a comparably stable dielectric constant of 2400. In addition, the capacitance properties and the electrical breakdown strength of BST/LNO hetero-structure thin films are also thickness-dependent, respectively. The electrical breakdown strength reached a maximum value of 1237 kV/cm in the BST/LNO hetero-structure thin film with ~73 nm BST layer.

Synthesis and characterization of Bi0.5(Na0.8K0.2)0.5TiO3-based ceramics obtained through the sol-gel method

The effect of the sintering temperature on the formation of secondary phases and ferroelectric properties of Bi0.5(Na0.8K0.2)0.5TiO3 ceramics has been studied. Ceramic powders were prepared by the sol-gel method and sintered at different temperatures. Samples were characterized by X-ray diffraction (XRD), Raman microspectroscopy, scanning electron microscopy, impedance spectroscopy and ferroelectric hysteresis loops. Through XRD and Raman results, the perovskite structure was detected, and the formation of secondary phases was registered. As the sintering temperature was increased, the secondary phase composition was modified. Moreover, dielectric properties were influenced by the resulting grain size and the secondary phase amount.

Influence of Bi Excess on the Structural and Morphological Properties of Bi0.5K0.5TiO3 Synthesized by Using the Hydrothermal Method and Its Nanogenerator Properties

This study investigated the effects of an excess of bismuth in Bi0.5K0.5TiO3 (BKT) on its structural and morphological properties. Two types of BKT samples were prepared using bismuth stoichiometry, where one with a Bi:K molar ratio of 1:1 (S-BKT) and the other with a ratio of 1.1:1 with 10 mol% excess of Bi (10% BKT). These samples were prepared using the hydrothermal synthesis method. When the X-ray diffraction (XRD) data for the two samples were compared, the 10% BKT shows a 1.3 times larger than that for the S-BKT sample in the ratio of the secondary phase peak to the BKT (101) peak at approximately 29.3°. Morphology analysis showed that both samples had agglomerations with diameters of approximately 200 nm and nanowires with lengths of 1–2 μm and diameters of 8 nm. The fractions of the total area occupied by agglomerations in the two samples were estimated at approximately 95% for 10% BKT and approximately 45% for S-BKT. These results indicate that an excess of bismuth affects the secondary phase and agglomeration formation. Nanogenerators were prepared by mixing S-BKT, and their output voltages were 1.8 V and their outputs currents were 4 nA.

A study on the field emission properties of Bi2Se3 nanostructures prepared by laser ablation

One of the effective methods known as pulse laser ablation in liquid (PLAL), in which a solid target material is immersed in an organic solvent and laser beam is irradiated through liquid on a target material, is a direct method used to generate nanoparticles in liquid medium. The present work is focused on the preparation of bismuth selenide (Bi2Se3) nanoparticles using PLAL to study their field emission characteristics. The PLAL was performed under nanosecond (ns) laser with different ablation time of 120 min and 240 min. The field emission characteristics were measured in the planer “diode” configuration in all metal ultra-high vacuum (UHV) chamber. The prepared Bi2Se3 nanoparticles were analyzed with different characterization techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-visible spectroscopy in order to study the surface morphology and structural information. The generation of Bi2Se3 nanoparticles is found after PLAL, which clearly suggests that bulk Bi2Se3 microsheet is transformed into Bi2Se3 nanoparticles. The X-ray spectra and UV spectra show the formation of nanoparticles upon laser ablation. The improvement in the field emission properties is found for laser-ablated Bi2Se3 nanoparticles. The field emission characteristics lead to increase in current density, which can be ascribed to the reduction in size of Bi2Se3 nanoparticles due to laser ablation. The prepared Bi2Se3 nanoparticles could be considered for novel applications in optoelectronics devices.

Holmium induced structural transformation and improved dielectric and magnetic properties in Bi0.80La0.20FeO3 multiferroics

Abstract The change in structural behaviour, magnetic measurement & dielectric characteristics of polycrystalline Bi0.80−xLa0.20HoxFeO3 (x = 0.00, 0.05, 0.10 & 0.15 and designated as LH0, LH05, LH10 and LH15 respectively) multiferroics prepared using method of the solid-state reaction, have been investigated. The powder X-ray diffraction and Rietveld refinement of the XRD spectrum indicates that Bi0.80La0.20FeO3 multiferroics have single phase in R3c. Rietveld refined spectrum of the XRD conclude that holmium substitution at A-site for the samples LH05 and LH10 is crystallized as combo of rhombohedral R3c and orthorhombic Pbam space group. Holmium substitution for LH15 has changed the rhombohedral R3c symmetry of Bi0.80La0.20FeO3 to the orthorhombic Pbam symmetry. The magnetic behaviour was studied by recording magnetization with magnetic up to ±10 kOe. Weak ferromagnetic behaviour of all samples attributes that co-doping effectively concealed spiral spin configuration by altering the canting angle. Dielectric behaviour of prepared ceramic compounds was carried by impedance analyser within frequency ranged 100 Hz–7 MHz for different temperatures.

Effects of ZBS glass addition on sintering behavior and properties of Ba6−3x(Sm1−yBiy)8+2xTi18O54(x = 2/3, y = 0.1) microwave dielectric ceramics

The ZnO-B2O3-SiO2(ZBS)-doped Ba6−3x(Sm1−yBiy)8+2xTi18O54 (x = 2/3, y = 0.1, BST) microwave dielectric ceramics were prepared via solid-state reaction route. The sintering behavior, microstructure and microwave dielectric properties of the ceramics were investigated systematically. The main crystalline phase of the ceramics was orthorhombic tungsten-bronze structure. But more than 3 wt% ZBS content leaded to secondary phase which were Bi0.56Sm1.44Ti2O7 and BaTi7O14. The results illustrated that large addition of ZBS would have an effect on the formation of the pure phase of BST(x = 2/3, y = 0.1) ceramics. The addition of ZBS as liquid phase sintering aid lowered the sintering temperature of BST ceramics successfully from 1250 to 1050 °C. However, excessive ZBS doping deteriorated the dielectric properties of ceramics dramatically. Considering the sintering temperature and microwave dielectric properties of the samples, the BST ceramics with 3 wt% ZBS doping content sintered at 1100 °C had the good dielectric properties: er = 68.4133, Q × f = 1879.89 GHz, τf = − 18.57 ppm/ °C.

Characterization and Physical Properties of Ba0.9Sb0.1TiO3 Solid Solution

Characterization and Physical Properties of Ba_0.9Sb_0.1TiO₃ Solid Solution

Microstructure and properties of Bi 2 O 3 doped 0.8(K 0.52 Na 0.48 ) NbO 3 –0.2KSr 2 Nb 5 O 15 lead‐free ceramics

The 0.8(K0.52Na0.48)NbO3–0.2KSr2Nb5O15-yBi2O3 (0.8KNN-0.2KSN-yBi2O3) lead-free ferroelectric composite ceramics were synthesised using rod-like KSr2Nb5O15 (KSN) and isometric (K0.52Na0.48)NbO3 (KNN) particles as raw material. Effects of Bi2O3 doping content on microstructure, electrical, and optical properties were researched. The results indicated that the addition of Bi2O3 helps to densify 0.8KNN-0.2KSN-y Bi2O3 ceramics within limits without changing phase structure and microstructure. The dielectric constant and phase transition dispersion degree increased with the increase of Bi2O3 while the dielectric loss decreased. Besides, the dielectric tunability was maintained in the range of 43.7∼51.8%, and reached its maximum when Bi2O3 content was 1 wt%. In addition, the remnant polarisation P r and coercive field E c decreased with the increase of Bi2O3, as well as the optical transmittance of 0.8KNN-0.2KSN, but the transmittance of all samples was above 48%.

Impact mechanism of gel’s alkali circumstance on the morphologies and electrical properties of Ba0.80Sr0.20TiO3 ceramics

Ba0.8Sr0.2TiO3 (BST) nanopowder was successfully synthesized by Pechini sol-gel method under different temperatures. Not only were BaCO3 impurity phase production and transition temperature from cubic to tetragonal phase respectively set at 440 °C and 800 °C, but also barium (Ba) resided in a 12-coordinate site of crystal lattice was set at 580 °C by the techniques of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). In addition, gels at pH 3–8 were used to prepare BST ceramics and the ceramics morphology was characterized by scanning electron microscope (SEM). The interrelationship between morphology and electrical properties, which were associated with precipitation phase on the crystal boundary of BST ceramics, was studied in detail. Finally, the optimal electrical properties of the ceramics were comprehensively displayed in this work, i.e., er = 8113.81, d33 = 78 pC/N, kp = 14.96%, and Qm = 85.08 at pH 5.