Rhombohedral Bi Research Articles

In Situ Transformation of Hybrid Bismuth Halide into Rhombohedral Bismuth for Electrochemical CO2 Reduction to Formate

AbstractBi‐based electrocatalysts have attracted high attention due to their high selectivity for formate, low cost, and high biocompatibility. Surface modification with halides can adjust the surface charge distribution of metal catalysts, thereby regulating the binding force of the intermediate. Organic‐inorganic hybrid bismuth halides provide an alternative, especially low dimensional structures. Herein, zero‐dimensional hybrid bismuth halides containing Bi4I16 units (denoted as Bi4I16) was recommended as pre‐catalyst due to the Bi ⋅ ⋅ ⋅ Bi spacing in Bi4I16 is 4.760 Å, nearly equaling to the Bi ⋅ ⋅ ⋅ Bi spacing in rhombohedral Bi (4.750 Å). The equal spacing may be more beneficial for the electricity‐driven in situ conversion and rearrangement of Bi atoms in the catalytic process. As a contrast, zero‐dimensional bismuth halide containing Bi2I9 units (denoted as Bi2I9) with shorter Bi ⋅ ⋅ ⋅ Bi spacing (4.2415 Å) was prepared. The working electrode prepared by Bi4I16 ink was measured for CO2RR, and the partial formate current density can reach 8.2 mA cm−2 at −1.1 V vs RHE. The Bi4I16 catalyst delivers a maximum Faradaic Efficiency (FE, ~80 %) for formate at −0.86 V vs RHE and maintain a FE higher than 78.5 % after 16 h.

Type-II superconductivity at 9K in Pb–Bi alloy

In the present work, we report the synthesis of Pb–Bi alloy with enhanced Tc of up to 9K, which is higher than that of Pb. The alloy is synthesized via a solid-state reaction route in the vacuum-encapsulated quartz tube at 700°C in an automated furnace. The synthesized sample is characterized by X-ray Diffraction(XRD) and Energy dispersive X-ray analysis(EDAX) for its phase purity and elemental composition. Rietveld refinement of XRD reveals that the end product is a majority hexagonal Pb7Bi3, with minor rhombohedral Bi. The electronic transport measurement shows metallic behavior with the Debye temperature of 108K and a superconductivity transition temperature (Tc) below 9K, which is the maximum to date for any reported Pb–Bi alloy, Pb or Bi at ambient pressure. Partial substitution of Bi at the Pb site may modify the free density of electronic states within the BCS model to attain the optimum Tc, which is higher by around 2K from the reported Tc of Pb. The superconductor phase diagram derived from magneto-transport measurements reveals that the synthesized alloy is a conventional superconductor with an upper critical field (Hc2) of 3.9 T, which lies well within the Pauli paramagnetic limit. The magnetization measurements carried out following ZFC(Zero Field Cool) protocols infer that the synthesized alloy is a bulk superconductor below 9K. The isothermal M-H(Magnetization vs. Field) measurements performed below Tc establish it as a type-II superconductor. The specific heat capacity measurements show that the Pb–Bi alloy is a strongly coupled bulk superconductor below around 9K with possibly two superconducting gaps.

Fabrication of 〈100〉-oriented Bi(Mg0.5Ti0.5)O3-modified BiFeO3-BaTiO3 ceramics and their piezoelectric properties

Rhombohedral Bi(Mg0.5Ti0.5)O3-modified BiFeO3-BaTiO3 ceramics were successfully textured along the nonpolar 〈100〉 direction using the templated grain growth process for the first time. The textured 0.90(0.33BaTiO30.67BiFeO3)0.10Bi(Mg0.5Ti0.5)O3 (33BTBF-10BMT) ceramics were fabricated by a 33BTBF-10BMT matrix with BT templates. The degree of orientation was investigated by various sintering temperatures, and the 80% oriented 33BTBF-10BMT along the 〈100〉 direction was achieved at a relatively high sintering temperature. However, the degree of orientation abruptly decreased at the highest sintering temperature of 1100 °C due to the large pores and low relative density. Based on the analysis of the unipolar strain measurements, the highest strain and d 33 * values were observed in the textured ceramics with 80% orientation. These textured ceramics exhibited approximately 0.3% strain and a d 33 * exceeding 400 pm V−1, representing approximately 1.5 times higher values compared to the nontextured ceramics.

Observation of large spin conversion anisotropy in bismuth

While the effective g-factor can be anisotropic due to the spin-orbit interaction (SOI), its existence in solids cannot be simply asserted from a band structure, which hinders progress on studies from such viewpoints. The effective g-factor in bismuth (Bi) is largely anisotropic; especially for holes at T-point, the effective g-factor perpendicular to the trigonal axis is negligibly small (<0.112), whereas the effective g-factor along the trigonal axis is very large (62.7). We clarified in this work that the large anisotropy of effective g-factor gives rise to the large spin conversion anisotropy in Bi from experimental and theoretical approaches. Spin-torque ferromagnetic resonance was applied to estimate the spin conversion efficiency in rhombohedral (110) Bi to be 17 to 27%, which is unlike the negligibly small efficiency in Bi(111). Harmonic Hall measurements supportthelarge spin conversion efficiency in Bi(110). A large spin conversion anisotropy as the clear manifestation of the anisotropy of the effective g-factor is observed. Beyond the emblematic case of Bi, our study unveiled the significance of the effective g-factor anisotropy in condensed-matter physics and can pave a pathway toward establishing novel spin physics under g-factor control.

Electrochemical properties of Bi2Se3 layers semiconductor elaborated by electrodeposition

• Bismuth selenide (Bi 2 Se 3 ) thin films with nanoparticles was electrodeposited from a nitric bath. • The electrodeposition mechanism of Bi 2 Se 3 alloy into ITO substrate is three-dimensional instantaneous nucleation. • The reaction of Bi 2 Se 3 deposition is quasi-reversible controlled by the diffusion process, with the diffusion coefficient D of Bi and Se in the Bi 2 Se 3 system are 1.756 10 -7 cm 2 s -1 and 0.196 10 -7 cm 2 s -1 , respectively. • The interesting properties of the resulting Bi 2 Se 3 make it a relevant material for future developments in photovoltaics and optoelectronics. The semiconductor, Bi 2 Se 3 layers was electrochemically deposited on Indium Tin Oxide substrate (ITO) from a nitric acid, Bi (NO 3 ) 3 ·5H 2 O and H 2 SeO 3 solution. The results of the electrochemical behavior of Bi 2 Se 3 were as follows: Cyclic voltammetry (CV) studies revealed that the electrodeposition of Bi 2 Se 3 was performed at a negative potential of −0.22 V vs SCE, according to a quasi-reversible reaction controlled by the diffusion process. Chronoamperometry (CA) showed that the electrodeposition of Bi 2 Se 3 follows a 3D instantaneous nucleation model with diffusion-controlled growth. X-ray diffraction analysis indicated that the resulting layers at −0.22 V vs SCE exhibited a Rhombohedral Bi 2 Se 3 structure with a preferred orientation (1 1 3) and the 2:3 stoichiometric ratio of Bi and Se was checked by EDS quantitative analysis. SEM images revealed the formation of a uniform size mainly consisting of nanoparticles with spherical shapes. The Bi 2 Se 3 obtained layers are n -type semiconductors with an optical band gap of 2.35 eV.

Structural evaluation of GaAs1−xBix obtained by solid-phase epitaxial growth of amorphous GaAs1−xBix thin films deposited on (0 0 1) GaAs substrates

We have structurally evaluated GaAs1−xBix obtained by solid-phase epitaxial growth of amorphous GaAs1−xBix thin films via transmission electron microscopy and related techniques. Amorphous GaAs1−xBix layers are obtained using a molecular beam epitaxy apparatus at 180 °C. When the amorphous GaAs1−xBix layer is annealed for 1 h at a medium temperature of 350 °C, an epitaxial GaAs1−xBix layer is grown on the GaAs substrate, forming a thick polycrystalline layer between the region above the epi-layer and the GaAs cap layer. In addition, three types of defects are generated in the region above the interface between the epi-layer and the substrate: small As precipitates (approximately 5 nm in diameter) and large zincblende GaAs1−xBix and rhombohedral Bi precipitates (10–15 nm in diameter). On the other hand, we found that a precipitate-free GaAs1−xBix epitaxial layer is grown after annealing for 1 h at 600 °C, forming only a small amount of zincblende GaAs1−xBix and rhombohedral Bi precipitates (no As precipitates) in the region above the epi/sub interface. Furthermore, the difference between the above results and in the case of low-temperature-grown molecular beam epitaxy GaAsBi crystals after annealing is discussed. We also observed varying features and distributions of the defects in LTG GaAs1−xBix layers (Tg = 250 °C) after annealing for 20 min at 600 °C from those of the same in a previous study: 1) rh-As precipitates are generated only at the epi/sub-interface; 2) Type-A (V-shaped) and Type-B (Λ-shaped) rh-Bi precipitates are generated in the upper and lower regions of the GaAs1−xBix layer, respectively. Based on these results, we discussed the origins of the above differences and factors affecting the generation of these precipitates.

The impact of intermetallic compound on microstructure, mechanical characteristics, and thermal behavior of the melt-spun Bi-Ag high-temperature lead-free solder

PurposeThis study aims to study the impact of intermetallic compound on microstructure, mechanical characteristics and thermal behavior of the melt-spun Bi-Ag high-temperature lead-free solder.Design/methodology/approachIn this paper, a new group of lead-free high-temperature Pb-free solder bearing alloys with five weight percentages of different silver additions, Bi-Agx (x = 3.0, 3.5, 4.0, 4.5 and 5.0 Wt.%) have been developed by rapidly solidification processing (RSP) using melt-spun technique as a promising candidate for the replacement of conventional Sn-37Pb common solder. The effect of the addition of a small amount of Ag on the structure, microstructure, thermal and properties of Bi-Ag solder was analyzed by means of X-ray diffractometer, scanning electron microscopy, differential scanning calorimetry and Vickers hardness technique. Applying the RSP commonly results in departures from conventional microstructures, giving an improvement of grain refinement. Furthermore, the grain size of rhombohedral hexagonal phase Bi solid solution and cubic IMC Bi0.97Ag0.03 phase is refined by Ag addition. Microstructure analysis of the as soldered revealed that relatively uniform distribution, equiaxed refined grains of secondary IMC Bi0.97Ag0.03 particles about 10 µm for Bi-Ag4.5 dispersed in a Bi matrix. The addition of trace Ag led to a decrease in the solidus and liquidus temperatures of solder, meanwhile, the mushy zone is about 11.4°C and the melting of Sn-Ag4.5 solder was found to be 261.42°C which is lower compared with the Sn-Ag3 solder 263.60°C. This means that the silver additions into Bi enhance the melting point. The results indicate that an obvious change in electrical resistivity (?) at room temperature was noticed by the Ag addition. It was also observed that the Vickers microhardness (Hv) was increased with Ag increasing from 118 to 152 MPa. This study recommended the use of the Bi-Ag lead-free solder alloys for higher temperature applications.FindingsSilver content is very important for the soldering process and solder joint reliability. Based on the present investigations described in this study, several conclusions were found regarding an evaluation of microstructural and mechanical deformation behavior of various Bi-Ag solders. The effect of Ag and rapid solidification on the melting characteristics, and microstructure of Bi-Ag alloys were studied. In addition, the mechanical properties of Bi with different low silver were investigated. From the present experimental study, the following conclusions can be drawn. The addition of Ag had a marked effect on the melting temperature of the lead-free solder alloys, it decreases the melting temperature of the alloy from 263.6 to 261.42°C. Bi-Ag solders are comprised of rhombohedral Hex. Bi solid solution and cubic Ag0.97Bi0.03 IMC is formed in the Bi matrix. The alloying of Ag could refine the primary Bi phase and the Bi0.97Ag0.03 IMC. With increasing Ag content, the microstructure of the Bi-Ag gradually changes from large dimples into tiny dimple-like structures. The refinement of IMC grains was restrained after silver particles were added into the matrix. The inhibition effect on the growth of IMC grains was most conspicuous when solder was doped with Ag particles. As a result, the Vickers microhardness of the Bi-Ag lead-free solder alloys was enhanced by more than 100% ranging from 118.34 to 252.95 MPa. Bi-Ag high-temperature lead-free solders are a potential candidate for replacing the tin-lead solder (Sn-37Pb) materials which are toxic to human and the environment and has already been banned.Originality/valueThis study recommended the use of the Bi-Ag lead-free solder alloys for high-temperature applications.

Forming-free resistive switching in ferroelectric Bi 0.97 Y 0.03 Fe 0.95 Sc 0.05 O 3 film for RRAM application

Electromechanical and resistive switching properties were investigated in ferroelectric rhombohedral Bi 0.97 Y 0.03 Fe 0.95 Sc 0.05 O 3 (BYFSO) film, grown on fluorine-doped tin oxide coated glass substrate. Piezoforce microscopy images of the BYFSO film after the electrical writing indicates the ferroelectric domains were switched completely towards the upward and downward direction at ± 8 V DC bias voltage, which is analogous to the ferroelectric hysteresis curve. The resistive switching effect was investigated on the Ag/BYFSO/FTO RRAM device configuration through conventional I − V characteristics. The charge transport process in Ag/BYFSO/FTO resistive device is transformed from Ohmic to space charge limited current conduction mechanism. The endurance characteristics ensure a stable bipolar resistive switching effect with a large memory window of OFF/ON ratio about ∼100 for 50 repeatable testing cycles. From the impedance spectroscopy analysis, it is observed that the bulk resistance plays a significant role during the SET-RESET process, by large degradation of resistance from megaohm (high resistance state) to kiloohm (low resistance state). The oxygen vacancy induced conductive filaments are responsible for achieving the various resistive states in the device.

Solidification behavior of nanoscaled tri-phasic bismuth-indium-tin alloy particles embedded in Al–Cu–Fe quasicrystalline matrix

The present manuscript aims to understand the solidification and alloying behavior of the nanoscaled multiphase Bi-In-Sn nanoparticles embedded in the icosahedral quasicrystalline (IQC) matrix, synthesized using the melt spinning route. Detailed transmission electron microscopy (TEM) investigation reveals the formation of three distinct phases; tetragonal BiIn, rhombohedral (Bi), hexagonal (γ-Sn) or tetragonal (β-Sn) within the nanoparticles depending on the size. It also shows that BiIn and (Bi) exhibit a reasonably good lattice match with the IQC matrix, whereas (γ-Sn) does not obtain any orientation relationship with surrounding IQC. The DSC investigations show a sharp melting peak, whereas no distinct exothermic peak was observed on cooling, indicating solidification occurring over a range of temperatures. To investigate the extent of undercooling required for solidification, careful cyclic heating, and cooling experiments were performed in the DSC. The results suggest that the nanoparticles can completely be solidified by cooling to −160 °C, indicating extensive undercooling required for solidification. In-situ XRD during cooling depicts that the solidification is triggered by the nucleation of the primary (Bi) phase at 0 °C. Careful thermodynamic modeling of the Bi-In-Sn system with different nano-sizes were evaluated to interpret the size-dependent solidification behavior of the nanoalloy particles. The experimental results can be compared with the calculated nanophase diagram, presenting a reasonably good match.

Ambipolar two-dimensional bismuth nanostructures in junction with bismuth oxychloride

Despite the unique properties of bismuth (Bi), there is a lack of two-dimensional (2D) heterostructures between Bi and other functional 2D materials. Here, a coherent strategy is reported to simultaneously synthesize rhombohedral phase Bi nanoflakes and bismuth oxychloride (BiOCl) nanosheets. The delicate balance between several reactions is mediated mainly for the reduction and chlorination in the chemical vapor transport (CVT) process. The Bi-BiOCl lateral heterostructures have been constructed via the coalescence of the two different 2D nanostructures. The characteristics of ambipolar conducting Bi and insulator-like BiOCl are elaborated by scanning microwave impedance microscopy (sMIM). This work demonstrates a way to construct a 2D Bi nanostructure in junction with its oxyhalide.

Enhanced Thermoelectric Performance of Novel Reaction Condition-Induced Bi2S3-Bi Nanocomposites.

This is the first report on the enhanced thermoelectric (TE) properties of novel reaction-temperature (TRe) and duration-induced Bi2S3-Bi nanocomposites synthesized using a facile one-step polyol method. They are well characterized as nanorod composites of orthorhombic Bi2S3 and rhombohedral Bi phases in which the latter coats the former forming Bi2S3-Bi core-shell-like structures along with independent Bi nanoparticles. A very significant observation is the systematic reduction in electrical resistivity ρ with a whopping 7 orders of magnitude (∼107) with just reaction temperature and duration increase, revealing a promising approach for the reduction of ρ of this highly resistive chalcogenide and hence resolving the earlier obstacles for its thermoelectric application potentials in the past few decades. Most astonishingly, a TE power factor at 300 K of the highest Bi content nanocomposite pellet, made at 27 °C using ∼900 MPa pressure, is 3 orders of magnitude greater than that of hot-pressed Bi2S3. Its highest ZT at 325 K of 0.006 is over twice of that of similarly prepared CuS or Ag2S-based nanocomposites. A significantly improved TE performance potential near 300 K is demonstrated for these toxic-free and rare-earth element-free TE nanocomposites, making the present synthesis method as a pioneering approach for developing enhanced thermoelectric properties of Bi2S3-based materials without extra sintering steps.

Melting behaviour of tri-phasic Bi44In32Sn23 alloy nanoparticle embedded in icosahedral quasicrystalline matrix

Tri-phasic nanoscaled (Bi,In,Sn) alloy nanoparticles (NPs) embedded in the icosahedral quasicrystalline (IQC) matrix were synthesized by the rapid solidification route. The microstructure of the NPs was analyzed using transmission electron microscopy (TEM), which typically reveals the combination of three phases; rhombohedral (Bi), body-centered tetragonal BiIn and hexagonal (γ-Sn) in each NP. TEM study also indicates that (Bi) and BiIn bear a reasonably good lattice match with surrounding IQC, whereas (γ-Sn) does not develop any specific orientation relationship. In order to understand the melting behavior of tri-phasic NPs, extensive DSC (differential scanning calorimetry), in-situ TEM (transmission electron microscopy) and in-situ XRD (X-ray diffraction) has been carried out. The DSC result reveals substantial depression of melting temperature (∼20 °C) as compared to bulk. In-situ studies also indicate the solid-state transformation of (γ-Sn) into (β-Sn) prior to melting. As the temperature advances, melting initiates at the triple junction of (Bi)/BiIn and matrix. BiIn first melts completely, and the melt front grows into the (β-Sn) phase of the NP. Subsequently, the melt propagates into the interior of (Bi) rich region. The present study provides an insight into the formation of non-equilibrium (γ-Sn) phase instead of (β-Sn) and the mechanism of the melting behaviour of three-phase NP embedded in IQC.

Superconducting-like behavior of Bi/Bi2O3 interface

Metastable superconducting-like behavior of rhombohedral Bi samples exposed to surface oxidation under special conditions has been observed below the critical temperature range of 15–35 K. The ac magnetic susceptibility and electrical resistance measurements imply that the superconductivity appears in the Bi/Bi2O3 interfacial layer formed at the surface of the samples.

Lattice softening enables highly reversible sodium storage in anti-pulverization Bi–Sb alloy/carbon nanofibers

The high theoretical capacity of Sb-based intermetallic alloys makes them attractive potential anode materials for sodium-ion batteries (SIBs) with high energy density. However, their cycling stability is greatly restricted by the huge volumetric variations resulted from the intrinsic (de-)alloying mechanism. Herein, we demonstrate a unique lattice softening mechanism, which enables highly reversible sodium storage and stable cycling of the as-prepared Bi–Sb alloy/carbon nanofibers electrodes. Theoretical analyses show that the elastic modulus of Bi–Sb alloys is reduced whereas the toughness is enhanced by tuning the lattice chemistry of rhombohedral Bi–Sb alloys, which is of great importance in relieving the concentrated stress during the continuous (de-)sodiation processes. In-situ characterization and electrochemical evaluations demonstrate that the electrodes made of BiSb3/C nanofibers exhibit high anti-pulverization capability upon Na-cycling and extraordinary long-life cyclability. Specifically, a highly reversible capacity of 233.2 mAh g−1 at 2 A g−1 is achieved over 2500 cycles. Moreover, a full cell assembled with the pre-sodiated BiSb3/C anode and a Na3V2(PO4)3/C cathode delivers a high reversible capacity of 333.2 mAh g−1 at 0.2 A g−1 over 200 cycles. This present work provides further understandings and new solution for developing high-performance alloying-based anodes for SIBs.

Evidence of High-Temperature Superconductivity at 18 K in Nanosized Rhombohedral Bi Enhanced by Ni-Doping.

Superconductivity in bulk rhombohedral Bi has recently been detected to appear below 0.53 mK and 5.2 μT. Here, we unambiguously demonstrate that superconductivity in rhombohedral Bi can be greatly enhanced by incorporating Ni ions onto the Bi sites and reducing the size to the nanometer scale. The superconducting transition temperature TC of 12 nm rhombohedral Bi nanoparticles (NPs) reaches 4 K at ambient pressure. TC is significantly enhanced to reach 7, 12, and 18 K in 6, 8, and 10% Ni-doped Bi NPs, respectively, where superconductivity is found to coexist with ferromagnetism. Ni-doping causes a significant amount of electronic charges to shift toward the interconnecting regions between neighboring Bi ions. First-principles calculations reveal that the Ni ions serve as charge and spin suppliers for the developments of superconductivity and ferromagnetism.

HRTEM Study of Size‐Controlled Bi Quantum Dots in Annealed GaAsBi/AlAs Multiple Quantum Well Structure

High‐resolution transmission electron microscopy (HRTEM) study of statistically large number of Bi quantum dots (QD) in annealed GaAsBi/AlAs multiple quantum well (MQW) structures is presented in this work. Superlattices containing 20 alternating periods of 10 nm thick GaAsBi quantum well and AlAs 20 nm thick barrier layers are grown on semi‐insulating GaAs at 330 °C temperature. Dispersed Bi quantum dots are formed within the bismide layers during a post‐growth annealing at 750 °C. Energy dispersive X‐ray (EDX) mapping and high‐angle annular dark‐field scanning transmission electron microscopy (HAADF‐STEM) analysis reveal that GaAsBi phase is altered during the annealing treatment forming a partially Bi‐depleted GaAsBi phase and semiconducting Bi nanoparticles. AlAs layers are found to act as barriers for Bi out‐diffusion, thus controlling the size of the QDs. The analysis of HRTEM micrographs confirms that Bi quantum dots consist of a rhombohedral Bi phase randomly distributed within zinc blende GaAsBi layers. Geometric phase analysis (GPA) also shows that GaAsBi layers are strained with respect to AlAs layers, as supported by the high‐resolution X‐ray diffraction (HRXRD) data. These findings demonstrate a highly controlled synthesis of Bi‐based quantum dots and pave the way for future applications in the field of infrared devices.

Microstructure and electrical transport in electrodeposited Bi films

The semimetal character of bismuth and its large photon absorbing power make of this element the most suitable absorber material for X-ray low temperature detectors. This application requires coatings of Bi with thicknesses and properties that only electrodeposition methods may achieve. Although there are studies on electrodeposition of bismuth for these detectors and other devices, the process is not straightforward and has not been sufficiently studied in terms of the desired final properties, neither the effect of different parameters is well known or easily reproduced. This work reports the influence of two different electrolytes, of the deposition method, and of heating and stirring on the structure, microstructure and transport properties of bismuth films. Typically, rhombohedral Bi is obtained upon electrodeposition with very good crystallinity, and some crystal preferential orientation, while significant empirical correlations are found among electrochemical parameters, microstructure, and resistivity. Such correlation allows the identification of the deposition parameters for coatings that yield the optimal functional properties.

Slight Symmetry Reduction in Thermoelectrics

Thermoelectric research on germanium telluride (GeTe) has been mainly focused on the enhancement of its performance in the high-temperature cubic phase since the 1960s. Recently in Joule, Pei and co-workers achieved an unprecedented thermoelectric figure of merit in rhombohedral-phase GeTe by exploiting slight symmetry breaking in the structure, which simultaneously improved the electronic properties and reduced the lattice thermal conductivity.

Effect of the Synthesis Conditions and Microstructure for Highly Effective Electron Shields Production Based on Bi Coatings

Microelectronic products are very sensitive to ionizing radiation (electrons, protons, heavy charged particles, X-ray, and γ radiation). Lead is the commonly used material for radiation protection. Bismuth deposition has become an interesting subject for the electrochemical community because of bismuth’s unique electrical, physical, and chemical properties. There is a limited number of authors dealing with deposition of continuous bismuth films onto metallic substrates by electrodeposition method. The conditions of Bi electrochemical deposition and the structure of Bi coatings were examined. X-ray diffraction patterns for all samples were indexed to rhombohedral Bi. Coatings with a signified texture (012) are formed in electrolyte without additives. With gelatin the growth texture changes, and the most intense reflex becomes (110). It was found that increasing gelatin concentration from 0.1 to 0.5 g/L leads to Bi microstructural refinement from 4–20 μm, to from 50 nm to 2 μm, respectively. The protection ...

Correlation of the synthesis conditions and microstructure for Bi-based electron shields production

The various ionizing radiations (electrons, protons, heavy charged particles, X-ray and gamma radiation) are the damaging factors for microelectronic products. The common used material for radiation protection is lead. Recently, Bi deposition has become an interest for the electrochemical community because of bismuth's unique electrical, physical and chemical properties. There is a limited number of authors dealing with Bi films onto metallic substrates by electrochemical deposition. The electrochemical deposition conditions and Bi coatings structure were examined. X-ray diffraction patterns for all samples were indexed to rhombohedral Bi. Coatings with a signified texture (012) are formed in electrolyte without additives. With gelatin adding the growth texture changes and the most intense reflex becomes (110). It was found that gelatin concentration increasing from 0.1 to 0.5 g/L leads Bi microstructural refinement from 4-20 μm to 50 nm-2 μm, respectively. The protection efficiency of shields based on Bi under 1,6–1,8 MeV electron radiation energy was measured. The electron beam attenuation efficiency was estimated by the changing of current-voltage characteristics of semiconductor test structures which were located behind the shields and without them. It has been determined that optimal protection effectiveness and mass-dimensional parameters have Bi shields with 2 g/cm2 reduced thickness and 156 attenuation coefficient.