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It was reported that a bismuth iron borate amorphous oxide glass, 10Fe3O4–45Bi2O3–45B2O3, exhibits a low electronic conductivity (σ) of ∼10−8 S/cm at room temperature. In this study, we have found that fluorine addition drastically enhances its σ to six orders of magnitude higher σ of ∼10−2 S/cm in a 21Fe3O4–4BiF3–30Bi2O3–45B2O3 glass. Additionally, it is experimentally confirmed that a high electron density of ∼1017 cm−3 at 400 °C is achieved. X-ray photoemission spectroscopy reveals Bi–F, Fe–F, and B–F bondings, supporting the fluorine substitution at oxygen sites. The fluorine-added bismuth iron borate glass would be expected in semiconductor applications such as a thermistor operating at 25–400 °C. [ABSTRACT FROM AUTHOR]

Sodium bismuth titanate (NBT) reveals a rhombohedral (R3c) phase at room temperature. Ferroelectricity reduces with the advent of a tetragonal (P4bm) phase at the depolarization temperature, Td ∼ 456 K. AC conductivity (σac) studies exposed a small-to-large polaron transition at Td. Barrier energy (WH) was ∼1.60 eV at T < Td for the small polarons in the R3c phase, which drastically reduced to ∼0.043 eV with the advent of the P4bm phase for the large polarons for T > Td. This is associated with the sharp rise in conductivity for T > Td. Ab initio calculations consider the electronic distortion due to oxygen vacancies, which creates trap states in the band structure. The energy gap (ΔE) between the trap states and the conduction band was ∼1.4 eV (R3c) and ∼0.2 eV (P4bm). These values are comparable to the experimental WH. The P4bm phase is more distorted than the R3c phase from charge density and structural distortion calculations. This indicates the formation of large polarons in the P4bm phase, compared to that of small polarons in R3c. The formation energy of the polaron (Epolaron) was calculated from the structural distortion and electron localization energies. The P4bm phase shows lower Epolaron (−0.26 eV) than R3c (−0.36 eV), indicating higher conductivity for the P4bm phase. NBT was chemically modified by adding BCZT to validate the small to large polaronic crossover at Td. This is discussed in light of σac measurements. WH decreased with BCZT incorporation, thereby increasing the conductivity. This is a consequence of the increased lattice distortion due to BCZT incorporation. [ABSTRACT FROM AUTHOR]

The heavier group 15 elements As, Sb, and Bi are more restricted in their biochemistry than the nearly ubiquitous lighter congeners N and P, but organisms do encounter compounds of these elements as environmental toxins, starting materials for secondary metabolite biosynthesis, substrates for primary metabolism, or exogenously applied medicines. Under many physiological conditions, these compounds are transformed into pnictogen(III) species, the soft Lewis acidic character of which leads them to interact strongly with biologically relevant soft Lewis bases such as small-molecule thiols or cysteine residues of proteins and peptides. The archetypal complexes As(Cys)3, Sb(Cys)3, and Bi(Cys)3 have been studied in the past but a lack of detailed information about their molecular structures has hampered the analysis of protein structures featuring As(III), Sb(III), and Bi(III) bound to cysteine thiolate residues. In many cases, the formation of such protein adducts is proposed to play a key role in the mechanism of action of inorganic drugs that feature these elements. Here, we refine synthetic strategies to access As(Cys)3, Sb(Cys)3, and Bi(Cys)3, describe their crystal structures, analyze structural trends across the series and across Pn(SR)3 compounds deposited in the Cambridge Structural Database, and compare their features to the structures of proteins with these centers bound to Cys3 motifs. Significant differences were noted for many of the protein structures.

Body-centered cubic bismuth (bcc-Bi) has long been considered an ideal pressure standard/calibrant; thus, the accurate knowledge of both its equation of state (EOS) and melting curve is of primary importance for future high pressure and high temperature experiments. However, its melting curve has never been measured experimentally beyond 5 GPa, and several theoretical calculations do not agree with each other and, in fact, differ by as much as a factor of 2 with regard to the bcc-Bi melting point at 50 GPa. Here, we present the calculation of the melting curve of bcc-Bi to 400 GPa via quantum molecular dynamics simulations using the Z method implemented with VASP. We also present the ab initio EOS of bcc-Bi as well as its principal Hugoniot, which both appear to be in excellent agreement with the available experimental data. At 100 GPa, the temperature extent (from zero to melt) of bcc-Bi is comparable to that of gold. At pressures of $\stackrel {\gt }{ \sim }500$ GPa, the melting curve of bcc-Bi is (quasi-)parallel to, being ${\sim } 1000$ K below that of rhenium, the highest melter above ${\sim } 30$ GPa among the elements of the third row of the periodic table, which makes bcc-Bi the second highest melter behind Re. [ABSTRACT FROM AUTHOR]

In this work, we show how diffraction-based chemically sensitive dark-field transmission electron microscopy (DFTEM) reveals the presence of Bi hetero-antisites (BiGa) at the interface of Ga(As,Bi)/(Al,Ga)As quantum well (QW) structures grown by molecular beam epitaxy on GaAs(001). The presence of BiGa is demonstrated by the striking appearance of "dark-lines" at the interfaces under two-beam DFTEM imaging conditions using the (002) diffraction spot. Additional analytical scanning (S)TEM procedures reveal Ga depletion and Bi accumulation at the exact position of the dark-lines, consistent with BiGa at this location. The precise location of the dark-lines agrees with the position of growth interruptions made to adjust substrate temperature and the As/Ga flux ratio and, most importantly, the realization of a Bi pre-treatment before QW growth. We believe the Bi pre-treatment may have favored formation of BiGa hetero-antisites. We validate the use of g002 DFTEM for further investigations of the intricate bismuth incorporation into the lattice and its dependence on the growth conditions. Finally, g002 DFTEM imaging is positioned as a very powerful technique for the detection of point defects in general in materials with the zinc-blende crystal structure, beyond dilute bismide alloys. [ABSTRACT FROM AUTHOR]

BiFeO3–BaTiO3 (BF–BT) ceramics with high Curie temperature and excellent piezoelectric coefficient are expected to be applied in high-temperature piezoelectric sensors and actuators. However, its resistivity decreases rapidly with temperature and impedes its further applications. Moreover, normal methods such as doping modification cannot address this issue. In the present work, bismuth layered Bi4Ti2.93(Zn1/3Nb2/3)0.07O12 (BIT) and perovskite 0.36BiScO3-0.64PbTiO3 (BSPT) ceramics were selected as insulating layers and were, respectively, sintered with 0.7BF–0.3BT ceramics to form laminated ceramics. The heterojunction structures effectively prevent carrier migration, and both resistivities of BIT and BSPT laminated ceramics were increased from 106 to 108−9 Ω cm at 300 °C. In addition, piezoelectric properties of the BSPT-type laminated ceramics are much higher than that of BF–BT ceramics, in which the bipolar strain was increased from 0.04% to 0.1% (4 kV/mm), and d33 was increased from 140 to 237 pC/N. Therefore, designing the insulating layer may be an effective method to realize the high-temperature application for BF–BT ceramics. [ABSTRACT FROM AUTHOR]

Nickel/bismuth (Ni/Bi) bilayers have recently attracted attention due to the occurrence of time-reversal symmetry breaking in the superconducting state. Here, we report on the structural, magnetic, and electric characterization of thin film Ni/Bi bilayers with several Bi thicknesses. We observed the formation of a complex layered structure depending on the Bi thickness caused by the inter-diffusion of Bi and Ni which leads to the stabilization of NiBi 3 at the Bi/Ni interface. The superconducting transition temperature and the transition width are highly dependent on the Bi thickness and the layer structure. Magnetoelectric transport measurements in perpendicular and parallel magnetic fields were used to investigate the temperature-dependent upper critical field within the framework of the anisotropic Ginzburg–Landau theory and the Werthamer–Helfand–Hohenberg model. For thicker samples, we observed a conventional behavior, similar to that shown by NiBi 3 bulk samples, including a small Maki parameter (α M = 0), no spin–orbit scattering (λ S O = 0) and nearly isotropic coherence length (γ = ξ ⊥ (0) / ξ ∥ (0) ≈ 1). The values obtained for these properties are close to those characterizing NiBi 3 single crystals. On the other hand, in very thin samples, the Maki parameter increases to about α M = 2.8. In addition, the coherence length becomes anisotropic (γ = 0.32) and spin–orbit scattering (λ S O = 1.2) must be taken into account. Our results unequivocally show that the properties characterizing the superconducting state in the Ni/Bi are strongly dependent on the sample thickness. [ABSTRACT FROM AUTHOR]

The discovery of graphene led to a burst in search for 2D materials originating from layered atomic crystals coupled by van der Waals force. While bulk bismuth crystals share this layered crystal structure, unlike other group V members of the periodic table, its interlayer bonds are stronger such that traditional mechanical cleavage and exfoliation techniques have shown to be inefficient. In this work, we present a novel mechanical cleavage method for exfoliating bismuth by utilizing the stress concentration effect induced by micro-trench SiO 2 structures. As a result, the exfoliated bismuth flakes can achieve thicknesses down to the sub-10 nm range, which are analyzed by atomic force microscopy and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting for green hydrogen production is hindered by the sluggish kinetics of oxygen evolution reaction (OER). Loading a co-catalyst is essential for accelerating the kinetics, but the detailed reaction mechanism and role of the co-catalyst are still obscure. Here, we focus on cobalt oxide (CoOx) loaded on bismuth vanadate (BiVO4) to investigate the impact of CoOx on the OER mechanism. We employ photoelectrochemical impedance spectroscopy and simultaneous measurements of photoinduced absorption and photocurrent. The reduction of V5+ in BiVO4 promotes the formation of a surface state on CoOx that plays a crucial role in the OER. The third-order reaction rate with respect to photohole charge density indicates that reaction intermediate species accumulate in the surface state through a three-electron oxidation process prior to the rate-determining step. Increasing the excitation light intensity onto the CoOx-loaded anode improves the photoconversion efficiency significantly, suggesting that the OER reaction at dual sites in an amorphous CoOx(OH)y layer dominates over single sites. Therefore, CoOx is directly involved in the OER by providing effective reaction sites, stabilizing reaction intermediates, and improving the charge transfer rate. These insights help advance our understanding of co-catalyst-assisted OER to achieve efficient water splitting. [ABSTRACT FROM AUTHOR]

The formation of electron and hole traps in semiconductors via atomistic defects is the fundamental microscopic mechanism for tuning the electronic and photonic properties of these materials. Here we find in experiments that bismuth atoms doped into anatase TiO2 as substituents can appear as paired diatomic defects. Through first-principles density functional theory calculations, we reveal that the observed bismuth pair is separated by a medium distance of 6.37 Å through a delicate balance of Pauli repulsion and effective attractive interaction. We further clarify that the effective attractive interaction is related to the exchange coupling between the two bismuth defect states, which also leads to the formation of a spin singlet electronic state of the two unpaired electrons. Our study brings up a new type of defect state in TiO2, and motivates further experimental and theoretical studies of multi-electronic states in materials. [ABSTRACT FROM AUTHOR]

The catalytic intermolecular cyclization of thiophenols with allylic alcohols in the presence of bismuth triflate afforded the corresponding thiochromane derivatives in a one-pot reaction. The Bi(OTf)3-catalyzed reaction was also applied to the intermolecular cyclization of diaryl disulfides with 3-methylbut-2-en-1-ol to produce the corresponding thiochromanes. [ABSTRACT FROM AUTHOR]

This study investigates the impact of neodymium substitution for bismuth in SrBi 2 Nb 2 O 9 (SBN) ceramics, a potential lead-free alternative for ferroelectric applications. X-ray diffraction analysis reveals a decrease in lattice parameters and volume with increasing Nd content. Scanning electron microscopy examines the influence of neodymium on grain morphology, showing a transition from characteristic SBN plate-like grains to a mix of plates and micro-spheres. Dielectric properties are evaluated, showing an increase in room-temperature permittivity for Nd-doped samples compared to the undoped counterparts. Additionally, the influence of Nd doping on relaxor ferroelectric behavior is studied. The Curie temperature (Tc) increases with Nd concentration, while the temperature dependence of relaxation time weakens. Ferroelectric properties exhibit significant changes due to Nd doping. Inverse permittivity versus temperature (ϵ r −1 vs. T) measurements suggest an unconventional response, potentially due to lattice strain induced by the larger ionic radius of Nd. The potential influence of doping concentration on the order of the ferroelectric transition is also explored. Overall, neodymium substitution in SBN ceramics enhances their ferroelectric properties, making them promising for advanced electronic applications. [ABSTRACT FROM AUTHOR]

Nowadays, researchers are extremely fascinated with the study of the doping effects of nanostructures of different materials, sizes and concentrations in high Tc superconductors. This paper presents the presence of nanorods (N) structures, which have not previously been observed in the bulk HTSCs materials, and the influence of Iron doping in Bi-2223 superconductor using composition Bi2Sr2Can−1(Cu1−xFex)nO10+δ, (n=3) for (x=0.00 and 0.01). The composition is prepared through a solid state route (SSR). The obtained samples are characterized with XRD, FESEM with EDX, HR-TEM and FTIR, and categorized into two samples (α) and (β) Bi2Sr2Ca2Cu3O10+δ, and Bi2Sr2Ca2(Cu0.99Fe0.01)3O10+δ, respectively, which show Lattice dimensions a=5.3912Å, b=5.4075Å, c=6.7961Å and a=5.4031Å, b=5.4170Å, c=36.7944Å with Orthorhombic crystal structure, respectively. The FE-SEM micrographs show plate-like layered structures and (N) in the samples, which are uniformly distributed. The obtained size of crystallite nanoparticles is 2nm–100nm, calculated by the Scherrer method, and verified with HR-TEM data. The HR-TEM study also confirmed the layered form in the orthorhombic phase. The FESEM-EDX energy peaks in the spectrum confirm the presence of the elements in both samples (α) and (β). The HRTEM-EDX confirms the extant iron in the sample in the form of (N). The FTIR bond stretching 1630.89cm−1 and 1629.657cm−1 of the samples (α) and (β), respectively, confirms the superconductor bismuth-based 2223 phase, respectively. The electrical resistivity study of (α) and (β) samples shows the critical temperature (Tc) of 63.083K and 22.8195K, respectively. The onset temperature for both samples is measured at 115.1785K and 68.314K, which represent the Bi-2223 phase. The magnetoresistance is obtained at low temperatures by a physical properties measurement system (PPMS) and with the increasing order of applied magnetic field from 0 to 12 Tesla, an increase in the resistivity in the pure sample (α) and also a decrease in transition temperature are observed. These results are as similar to those obtained in the Bi-2223 Superconductor. The results show the growth of nanoparticles in the iron-doped Bisco superconductors. [ABSTRACT FROM AUTHOR]