Bi Content Research Articles

Influence of Te replacement by Bi in In10Se70Te20-xBix films and its structural, optical, morphological, surface wettability and thermal behaviors for optoelectronic applications

The current investigation is based on Bi doping into In–Se–Te alloy and its impact on the surface morphology, structure, and optical behaviors. The transition from In10Se70Te20 to In10Se70Bi20 composition modified its structural phases as observed from X-ray diffraction study. The crystallite size increased from 9.55 nm to 14.04 nm. The lattice strain decreased from 0.0234 to 0.0106 with Bi content. Raman study infers the microstructural and phase formation in the films. The structure change is associated with change in surface morphology as noticed from field emission scanning electron microscopy images. The composition of In10Se70Te20-xBix (x = 0, 5, 10, 15, 20 at %) films were observed from energy dispersive X-ray analysis. The UV–Vis–NIR data showed the decrease in transmittance from 80 % to 10 % at 2100 nm wavelength with Bi%. The decrease in direct bandgap from 1.64 eV to 1.37 eV was discussed by Davis-Mott model for density of defect states. The increase in Urbach energy from 101 meV to 161 meV is based on the transition from In10Se70Te20 to In10Se70Bi20 composition. The optical parameters like optical density, extinction coefficient and absorption coefficient were increased with Bi addition. The calculated static linear refractive index by different model at different Bi% satisfies Moss's relation. The enhanced non-linear susceptibility from 2.96 × 10−10 esu to 3.33 × 10−10 esu and non-linear refractive index from 1.58 × 10−7 esu to 1.86 × 10−7 esu with Te replacement by Bi may be suitable for non-linear optical devices. The change in different theoretically calculated physical parameters were found to be in accordance with the experimental data. The surface wettability study showed the transition from hydrophilic to hydrophobic nature with increase in Bi %. The obtained experimental results for the films may be used for various photonic and optoelectronic device applications.

Revealing the Chemical Instability of Mg3Sb2-xBix-Based Thermoelectric Materials.

n-Type Mg3Sb2-xBix alloys have been regarded as promising thermoelectric materials due to their excellent performance and low cost. For practical applications, the thermoelectric performance is not the only factor that should be taken into consideration. In addition, the chemical and thermal stabilities of the thermoelectric material are of equal importance for the module design. Previous studies reported that the Mg3Sb2-xBix alloys were unstable in an ambient environment. In this work, we found that Mg3Sb2-xBix alloys reacted with H2O and O2 at room temperature and formed amorphous Mg(OH)2/MgO and crystalline Bi/Sb. The substantial loss of Mg resulted in a significant deterioration in thermoelectric properties, accompanied by the transition from n-type to p-type. With the increase in Bi content, the chemical stability decreased due to the higher formation energy of Mg3Bi2. A chemically stable Mg3Bi2 sample was achieved by coating it with polydimethylsiloxane to isolate H2O and O2 in the air.

Distribution of Ag, Au, Bi, Cu, and Mo in surface soils. Case study: Mitrovica region, Republic of Kosovo

ABSTRACT This article presents the results of a geochemical investigation of an anthropogenic group of metals (Ag, Au, Bi, Cu, and Mo) in the surface of the Mitrovica region, Republic of Kosovo. In order to determine their content and to evaluate the contamination level, 156 topsoil samples were collected in an area of 301.5 km2. The content of elements was determined by inductively coupled plasma-mass spectrometry. The results showed that the average content of Cu (42 mg/kg), Bi (1.5 mg/kg), Ag (0.44 mg/kg), and Au (2.7 μg/kg) exceeded their average content in European and world soils by 3.4 and 1.4 times; 3.0 and 7.5 times; 1.62 and 8.8 times and 2.7 and 1.8 times, respectively. The average Mo content (0.68 mg/kg) exceeded the average content in European soils by 1.09 times, while the average content in world soil was not exceeded. Copper levels exceeded the Dutch target value of 36 mg/kg in 152 km2 and the Dutch action value of 190 mg/kg in 6.2 km2 of the study area. The enrichment factor and geo-accumulation index values for the analysed elements indicate that their higher content is of anthropogenic origin, mainly due to lead and zinc mining and metallurgical activities in the study area. The quality of soils in the Mitrovica region varies from highly contaminated with copper and bismuth, with extremely high enrichment of Cu, Bi and Ag in the soils of the central zone (Zone I) and the urban soils of the cities of Zveçan and Mitrovica. Therefore, the establishment of a monitoring and treatment programme for contaminated soils in this zone would be necessary to protect human health .

Effect of Bi Content on the Microstructure, Mechanical and Tribological Properties of Cu-Sn Alloy.

To reduce the use of the toxic Pb element in the Cu-Sn alloy with high friction performance, Cu-xBi-10Sn alloys with different Bi contents were prepared by gravity casting, and the effect of Bi content on the microstructure, mechanical properties and wear property of Cu-Sn alloys were studied. The results showed that the Bi element was distributed in bands or long strips on the dendritic arms and did not form compounds with other elements. With the increase in Bi content, the hardness and tensile strength of Cu-xBi-10Sn alloys present a trend of increasing first and then decreasing. When the Bi content was 7 wt.%, the maximum hardness value was obtained, and the ultimate tensile strength was close to that of Cu-10Pb-10Sn alloy. Compared with Cu-10Pb-10Sn alloy, Cu-7Bi-10Sn alloy also possessed better friction reduction and wear resistance under the oil lubrication condition.

Boosting adsorption and dissociation kinetics of magnesium-chloride ion pair via bismuth/indium-based artificial interface

The formation of passivating interphases on Mg-metal anode is impeding the wide employment of rechargeable Mg-metal batteries with less safety and cost concerns. Despite engineering artificial interlayers offers an efficient solution, it still falls short of expectation because of the compromised Mg plating/stripping performances in conventional electrolyte systems. In this work, a unique bismuth/indium-based artificial interface is introduced, which enables an exceptional reversibility (lowest nucleation overpotential of 189 mV than that (583 mV) of pristine Mg anode), high rate capability (a stable charge and discharge operation at 5.0 mA cm−2 without short circuit) and good temperaturetolerance (being cyclable over 10 °C and 50 °C) for the first time. This bismuth/indium-based artificial interface is constructed by facile displacement reactions between Bi(CF3SO3)3/In(CF3SO3)3 and Mg. The dominant interphases, including Bi, In and BiOx species, can be controllably tailored via adjusting the relative ratio and concentration of Bi(CF3SO3)3/In(CF3SO3)3. Theoretical calculation results accompanied by electrochemical experiments indicate that kinetically favorable adsorption and dissociation processes of Mg-Cl ion pair on this interface, affording good magnesiophilic property and fast charge transfer kinetics, are responsible for the improved Mg-metal anode properties.

Exploration of the Structural, Dielectric, Ferroelectric, and Piezoelectric Properties in Non-stoichiometric Sr1−XBi2+2X/3Nb2O9 Ceramics

In this study, the authors focused on the preparation and characterization of Lead-free ferroelectric ceramics known as Sr1−XBi2+2X/3Nb2O9: SBBNX, where 0.0≤ × ≤0.4. The ceramics were synthesized using a conventional solid-state reaction route. The researchers performed X-ray diffraction (XRD) analysis to confirm the phase formation and employed the Rietveld refinement technique. The results indicated that the prepared SBBNX ceramics exhibited a single phase with an orthorhombic structure, specifically belonging to the A21am space group. All samples were subjected to analysis using field emission scanning electron microscopy (FESEM) to investigate their surface morphology. The micrographs revealed a uniform distribution of grains (of size 2–4 μm ) on the surface, with distinct grain boundaries. An increasing trend in both the dielectric constant (from 99 to 220 at room temperature) and transition temperature (from 396 °C to 490 °C) was noted with an increase of Bi content in SBN. The researchers estimated the activation energies by analyzing the Arrhenius plots of the ac conductivity. The obtained values ranged from 0.62 to 1.25 eV, indicating the presence of motion of oxygen vacancies in the SBBNX ceramics. The primary objective of this study was to optimize the Sr/Bi ratio in SBBNX ceramics to enhance their potential use in non-volatile random access memory (NVRAM) applications and high-temperature piezoelectric devices.

Geochemical features of sulfides of the Aktash magnetite-polymetallic deposit, Western Karamazar, Tajikistan (LA-ICP-MS data)

The distribution of trace elements in sulfdes from various ores of the Aktash magnetite-polymetallic deposit (Tajikistan) is studied using LA-ICP-MS method. Sulfdes partly replace banded magnetite ores. Each sulfde type exhibits specifc geochemical features. Galena from sulfde-magnetite ores contains the higher amount of elements of «high-temperature» association (Bi, Ag, Cu) than galena from pyroxene-sphalerite ores, which, in addition to Ag and Bi, also contains higher amount of elements of «medium-temperature» association (Se, Te, and Sb). Sphalerite from sulfde-magnetite and chlorite-pyrrhotite ores contains higher Fe, Cd and Mn amount than sphalerite from pyroxene-sphalerite ores, which is characterized by elevated Co and As contents. Pyrite is depleted in trace elements except for As, the content of which is maximum compared to other sulfdes. The Ag, Se, Bi, Zn, Cd and Ni contents of chalcopyrite from chlorite-pyrrhotite ores are higher than in chalcopyrite from sulfde-magnetite and pyroxene-sphalerite ores. Chalcopyrite from pyroxene-sphalerite ores is characterized by elevated Pb, As, Ge, Te and Sb contents. Relatively high Co, Ni and Se contents are determined in pyrrhotite. In addition to Fe, Cu, Zn, Pb and Au, which form minerals in all types of ores, we suggest by-product extraction of following elements from complex sulfde-magnetite, chlorite-pyrrhotite and pyroxene-sphalerite ores (the Bi, Ag, Se and Te contents of galena and Cd content of sphalerite are shown in brackets): Bi (19520–24650 ppm), Ag (7907–9650 ppm), Se (397–606 ppm) and Te (276– 436 ppm) from galena concentrate and Cd (8525–27670 ppm) from sphalerite concentrate.

Low-temperature ignition and mechanism of μAl coated with bismuth citrate

Because of the existence of an oxide layer on the surface of micron aluminum (μAl) powder, it is difficult to ignite. In order to improve μAl ignition, Al particles were coated with bismuth citrate (Bi(cit)) by a solvent evaporation method. The morphology of Al-Bi(cit) was observed by scanning electron microscope (SEM) showed that Bi(cit) was evenly distributed on the surface of Al particles. The ignition temperature was reduced and ignition delay time at different temperatures of the Al-Bi(cit) were tested in a transparent tube furnace. With the increase of Bi(cit) content, the ignition temperature and ignition delay time shortened, and the combustion flame captured by the high-speed camera was more bright. The test results showed that Al-20 wt% Bi(cit) has a low ignition temperature of 479 °C, and the ignition delay time at 450 °C is only 7 s. The thermal behavior of Al-Bi(cit) was studied by thermogravimetric analysis (TG-DSC). Combined with the characterization results of the products at different heating temperatures, the combustion mechanism was proposed and proved.

Optoelectronic characterization of Bi-doped ZnO nanocomposites for Schottky interlayer applications

In this study, Bi doped ZnO (Bi:ZnO) nanocomposites mixed with different weight-percentages (0.1, 0.3, 0.5% Bi) content were coated on the p-Si wafer via spin-coating method. Some main electrical and optical parameters of the Schottky structure with Bi doped ZnO interlayer have been evaluated in dark and under different illumination intensities (20, 40, 60, 80, 100 mW/cm2). Optical and electrical features of the Al/(Bi:ZnO)/p-Si (MIS) type PD were investigated and compared via current-voltage/time (I–V/t) and capacitance/conductance-voltage (C/G/w-V) measurements at 1 MHz. Main electrical parameters of them such as ideality factor (n), zero bias barrier height (ΦBo), and series resistance (Rs) were calculated on dark and 100 mV/cm2 illumination intensity. As a result of Ohm's law used in the determination of Rs, contribution rate increases while Rs values decrease. In addition, the electrical admittance measurements were made at 1 MHz. The C−2-V properties and the photovoltaic property of the diode was analysed according to the results obtained.

The ore-forming process of the Qingshan gold deposit, Qaidam Basin: Evidence from LA-ICP-MS trace element analysis and S-Pb isotopic compositions

The Qingshan gold deposit is located in the Tanjianshan ore collection area, which is in the northern margin of Qaidam Basin and is one of the most important gold and polymetallic metallogenic belts in China. Based on the field investigation and optical microscopic observations, mineralization at the Qingshan deposit can be divided into three stages: (1) quartz-pyrite stage, (2) quartz-sulfide-gold stage, (3) quartz-calcite stage. Pyrite from the stage 1 (Py1), stage 2 (Py2) and stage 3 (Py3) are selected for LA-ICP-MS trace element analyses. Pyrite from the stage 1 (Py1), stage 2 (Py2) are selected for in situ sulfur isotopes analysis. Pyrite from the stage 1 (Py1), stage 2 (Py2) and stage 3 (Py3), galena from the stage 1 (Gn1) and stage 2 (Gn2) are selected for in situ lead isotopes analysis. The result shows that Py1 is relatively rich in Co, Ni, Zn and Ag contents and lacking in Sb contents. Py2 is relatively rich in Cu, As, Sb, Au, Pb and Ag contents and lacking in Co, Ni and Bi contents. Py3 is relatively rich in Co, Ni and Bi contents and lacking in Zn, As, Au and Pb contents. The Au/As ratio shows that invisible gold occurs in the form of solid solution (Au+). The values of Au/Ag and Co/Ni ratio show that the pyrites in the Qingshan deposit are hydrothermal origin. The S isotope values of pyrite range from −4.33 to 4.97‰ (mean: 3.71‰, n = 31). The Pb isotope compositions with 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb values ranging from 18.002 to 18.791, 15.567 to 15.584, and 38.410 to 38.485, respectively. The results of in situ S-Pb isotopic indicate that sulfur and metals of the Qingshan deposit were mainly derived from the upper crust and orogenic belts. The Qingshan gold deposit is classified as an orogenic gold deposit, and was closely related to a large-scale ductile shear zone, which formed during the process of subduction between the Qaidam block and the Qilian block in the Variscan period. The mixing of fluids destroyed the stability of Au(HS)2- and is most likely the reason for gold precipitation.

Two-Stage Superimposed Gold Mineralization in the Xiejiagou Gold Deposit, Shandong Province: Insights from Fluid Inclusions, H-O-S Isotopes, and Trace Elements

The Xiejiagou gold deposit located in the Zhaoyuan-Laizhou gold belt is composed of altered-rock-type gold mineralization and superposed auriferous quartz veins, showing unique two-stage gold mineralization. Oxygen and hydrogen isotopic analyses yielded the following results: δ18OH2O = 0.8‰ to 4.4‰ and δD = −106‰ to −85‰ for altered-rock-type mineralization, and δ18OH2O = 3.6‰ to 5.6‰ and δD = −98‰ to −89‰ for auriferous quartz-veins. Combined studies on Co/Ni, Sb/Bi and As/Ag ratios of pyrites, it can be inferred that the ore-forming fluids were dominated by magmatic water mixed with very little meteoric water. The fractured altered rocks in the ore-hosting fault zones are characterized by mylonitization, cataclastic lithification, and structural lenses, reflecting a compressional (closed) ore-forming system. In contrast, the occurrence of auriferous quartz veins in fissures of altered-rock-type orebodies and the fact that altered-rock-type ores commonly occur as breccias cemented by auriferous quartz veins that reflect an extensional (open) ore-forming system for the vein mineralization. The increase in δ34S values from stage I (5.8‰–7.2‰) to stage II (6.6‰–9.0‰) indicate that the altered-rock-type mineralization was the result of intense water–rock interaction, while the occurrence of immiscible inclusions in auriferous quartz veins demonstrates that fluid immiscibility contributes significantly to gold deposition in the vein-type mineralization. Fluid-inclusion microthermometric data indicate that the fluids for the altered-rock-type mineralization are characterized by moderate-to-high temperature (262–368 °C), and low-to-moderate salinity (4.3–10.8 wt.% NaCl equivalent). In contrast, halite-bearing inclusions are found in auriferous quartz veins, and its fluids are characterized by moderate-to-high temperature (290–376 °C) and moderate-to-high salinity (5.1–41.9 wt.% NaCl equivalent). From early stages (I and II) to the late stage (III), homogenization temperature and high temperature element (W, Sn, and Mo) concentrations in pyrite first decrease and then increase, δ34S values and metallization-related element (Au, Ag, and Bi) concentrations in pyrite first increase and then decrease. Therefore, it can be inferred that the two distinct types of gold mineralization in the Xiejiagou gold deposit may be two separate mineralization events. The presence of magnetite in the auriferous veins suggests an increase in oxidation state during the vein mineralization. Importantly, the Xiejiagou gold deposit preserves two types of mineralization in a single deposit and uniquely records a metallogenic transition from a compressional, reduced environment to an extensional, oxidized environment, as a result of a regional stress field transition that occurred in the Zhaoyuan-Laizhou gold belt at ca. 120 Ma.

In Situ Trace Element and Sulfur Isotope Composition of Pyrite from the Beiwagou Pb-Zn Deposit, Liaodong Peninsula, Northeast China: Implications for Ore Genesis

The Beiwagou Pb-Zn deposit, located in the western part of the Liaodong Peninsula, is a carbonate-hosted stratiform deposit with a Pb + Zn reserve of 0.08 Mt @ 4.14% (Pb + Zn). The orebodies occur as conformable layers and lenses and are strictly controlled by strata (the Paleoproterozoic Gaojiayu and Dashiqiao Formations) and lithology (plagioclase amphibolite and dolomitic marble). Given that previous studies have focused only on the mineralization features and mineralogy of deposits, herein, we report in situ trace element analyses of pyrite using LA-ICP-MS, together with in situ sulfur isotopes of pyrite, to constrain the composition, substitution mechanisms, source of sulfur, and sulfate reduction pathways of pyrite in the Beiwagou deposit. Based on pyrite morphology, texture, and chemistry, four pyrite types were identified: subhedral, porous-to-massive pyrite (Py1) related to chalcopyrite; subhedral, porous crushed pyrite (Py2) associated with fine-grained sphalerite; rounded and porous pyrite (Py3) related to the Zn-rich part of the laminated ore; and anhedral, porous-to-massive pyrite (Py4) associated with pyrrhotite, arsenopyrite, sphalerite, and galena. Py1 is characterized by high As, Ag, Cd, In, Au, Cu, and Zn concentrations and low Te, Bi, and Mo concentrations, whereas Py2 has high concentrations of Co and Ni and low concentrations of other trace elements, such as Cu, Zn, Bi, and Te. Py3 is characterized by elevated As concentrations, low Co, Ni, In, W, Te, and Tl concentrations, and varying Pb concentrations, whereas Py4 has low Ag, Cd, In, Zn, Cu, and Mn concentrations and varying W, Co, Ni, Pb, Sb, and As concentrations. Significant correlations between some elements in each pyrite type suggest substitution mechanisms, such as (Zn2+ + Cu2+ + Mn2+ + Cd2+) ↔ 2Fe2+, Ag+ + (Sb)3+ ↔ 2Fe2+, and (Te+ + Ag+) + Sb3+ ↔ 2Fe2+, and the existence of a negative correlation between Co and Ni implies competition between both elements. The strongly positive δ34S values (12.11‰–23.54‰) are similar to that of seawater sulfates and likely result from thermochemical sulfate reduction (TSR). In conclusion, the Beiwagou Pb-Zn deposit is a typical SEDEX deposit and mineralization likely occurred during diagenesis.

Thermal decomposition behaviors and degradation kinetics of biobased polyesters with partial crosslinking to eliminate cyclic compounds

A series of poly(butylene adipate-co-butylene itaconate) (PBAPI) copolyesters with and without a small amount of ethylenediaminetetraacetic acid (EDTA) were synthesized via melt polymerization. Thermogravimetric analysis -gas chromatography/mass spectroscopy (TGA-GC/MS) techniques were used to identify the thermal degradation behaviors. By introducing 0.1 mol % EDTA into BA/BI = 10/0, the dominant degradation product was converted from furan and cyclopentanone derivatives to CO2 and formation of cyclic compounds was notably inhibited. Moreover, similar tendencies were observed when the BI content increased, demonstrating that the existence ratio of CO2 and furan derivatives increased while the concentrations of cyclopentanone and cyclic compounds reduced during decomposition. Finally, no cyclic compound product was detected in the BA/BI = 7/3 copolyester. These results indicate that the introduction of both EDTA and BI inhibits generation of cyclic compounds, which are attributed to the formation of partial crosslinking for chemical structures. The nonisothermal degradation kinetic was also carried out to investigate the decomposition behaviors. The activation energy requirements at each degradation stage varied with the composition of BA/BI ratios and the introduction of EDTA, demonstrating further evidence of degradation behavior transformation.

Dual-Cure Adhesives Using a Newly Synthesized Itaconic Acid-Based Epoxy Acrylate Oligomer.

Herein, a novel biomass-derived itaconic acid (IA)-based epoxy acrylate oligomer (EAO) is synthesized by means of the esterification reaction of the epoxy group of bisphenol A diglycidyl ether (BADGE) with the carboxylic group of IA. The detailed chemical structure of the as-prepared bisphenol A diglycidyl ether diitaconate (BI) is characterized via the KOH value, FT-IR spectrum, and 1H-NMR spectrum. Further, a dual-cure adhesive system is formulated using BADGE, acrylic acid, and trimethylolpropane triacrylate with various BI contents, and the adhesive performance is investigated by measuring the thermal stability, adhesive properties, pencil hardness, and surface energy properties. Thus, the dual-cure adhesive with a BI content of 0.3 mol is shown to provide excellent thermal stability, along with an adhesive strength of 10.7 MPa, a pencil hardness of 2H, and a similar surface energy to that of a typical polycarbonate film. In addition, the properties of the BI-based dual-cure adhesive are compared with those of the dual-cure adhesives based on bisphenol A glycerolate diacrylate or bisphenol A glycerolate dimethacrylate.

Investigation of Multi‐Phase Structure and Optoelectronic Performance of Bi‐Doped (Cu−Zn) Oxide Composite Thin Films

AbstractIn this research, thin film composite structures were used to prepare optoelectronic devices from bare and Bi‐substituted p‐CuO/n‐ZnO systems. The p‐CuO/n‐ZnO composite thin film structures were prepared by the SILAR technique, and the influences of two different Bi contents on the structure and main physical performances of the samples were investigated. The X‐ray diffraction (XRD) technique showed that the composited thin film materials were multiphased in rutile hexagonal (wurtzite) phase (ZnO) and monoclinic tenorite phase (CuO) type crystal structure. The obtained surface morphological results presented that the structure exhibits an almost homogeneous, plate‐like surface distribution, and depending on the increase of Bi concentration, the plate‐like sheet area widens from ~2.5 μm to 10 μm and the layer boundaries decrease. FT‐IR and Raman spectroscopy were used to investigate the various vibration and Raman active phonon modes of Bi:p‐CuO/n‐ZnO nanostructured heterostructures. For a comprehensive analysis of the optical bandgap of the fabricated composite samples, the estimated values were obtained from the Tauc plot. Produced samples exhibited an Ohmic behavior and dc resistivity values of films can be determined via Ohm′s Law. The adjusted sheet resistance value of 11.51 MΩ/sq when the content of Bi 3.0 % in the growth bath.

Study on the electrodeposition of Bi2Te3 thin film thermoelectric material in dimethyl sulfoxide

In this paper, the electrochemical behaviors of Bi3+ and Te4+ ions in dimethyl sulfoxide (DMSO) organic solvent were studied by testing the cyclic voltammetry curves and cathodic polarization curves. The diffusion coefficients of Bi3+ and Te4+ ions were investigated and calculated, and reduction difficulty of them was compared. Then, bismuth telluride thermoelectric thin films were prepared using potentiostatic electrodeposition mode in the electrolytes with different compositions at different potentials. The structure, morphology and compositions of the prepared thermoelectric materials were characterized and analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS). The results show that the redox processes of Bi, Te and bismuth telluride on Au electrode are all completely irreversible processes. The diffusion coefficient of Bi3+ ion has an order of magnitude of approximately 10−7 while that of Te4+ ion is about 10−5. The reduction of Bi3+ ion is more difficult than that of Te4+ ion in dimethyl sulfoxide organic solvent. The prepared thin film thermoelectric materials are bismuth telluride alloy, and the electrolyte composition and deposition potential have great influence on the structure, morphology and composition of the films. Increasing the concentration of Bi3+ ions in the electrolyte can greatly increase the content of element Bi in the deposits. In the electrolyte containing 20 mol·L−1 Bi(NO3)3·5H2O and 10 mol L−1 TeCl4, the bismuth telluride film electrodeposited at − 1.2 V has uniform grain size and compact structure, shows good surface morphology, and the atomic fraction ratio of Bi/Te element in the film is 1:1.80.

Distribution and sources of Ag, Au, Bi, Cu and Mo in surface soils. Case study: Mitrovica region, Republic of Kosovo

The objective of this study was to investigate the spatial distribution and content of a specificanthropogenic group of trace metals (Ag, Au, Bi, Cu and Mo) in surface soils (0 - 5 cm) of the Mitrovicaregion, Republic of Kosovo. The content of metals was determined by inductively coupled plasma - massspectrometry (ICP-MS). The average content of Cu (42 mg/kg), Bi (1.5 mg/kg), Ag (0.44 mg/kg) and Au(2.7 μg/kg) exceeded the average content of metals in European and world soils by 3.4 and 1.4 times, 3.0and 7.5 times, 1.62 and 8.8 times and 2.7 and 1.8 times, respectively. The average Mo content of 0.68 mg/kgexceeded the mean Mo content in European soil by 1.09 times, while the mean content in world soils wasnot exceeded. Copper levels were also found to exceed the Dutch target value of 36 mg/kg in 152 km2 andthe Dutch action value of 190 mg/kg on 6.2 km2 of the 301.5 km2of the study area. The values of theenrichment factor (EF) for the analyzed elements are all above 1.5, indicating that their higher content is ofanthropogenic origin, mainly due to lead and zinc mining and metallurgical activities in the study area. Thequality of the soils in the Mitrovica region varies from heavily contaminated with copper and bismuth, withextremely high enrichment of Cu, Bi and Ag in the soils of the central zone (Zone I) and the urban soils ofthe cities of Zveçan and Mitrovica.

Architecting Bismuth Molybdate Nanoparticles with Abundant Oxygen Vacancies and High Bismuth Concentration for Efficient N2 Electroreduction to NH3

AbstractN2 electroreduction reaction (NRR) enables an eco‐friendly NH3 synthesis under mild conditions, which is regarded as a carbon‐neutral alternative technology to the traditional Haber–Bosch process. However, its practical applications are seriously impeded by the difficulty in N2 adsorption and activation over catalysts, as well as the competing hydrogen evolution reaction (HER). In this work, a novel bismuth molybdate nanocatalyst with sufficient oxygen vacancies and high Biconcentration (41.9 at%), BiMoO‐OVs, is synthesized and demonstrated as an excellent NRR electrocatalyst. Benefiting from synergistic effect of the adequate Bi active centers with inert HER activity provided by the high concentration of Bi, and the reinforced N2 adsorption and activation ability of oxygen vacancies, the as‐synthesized BiMoO‐OVs presents a high Faradaic efficiency of 16.38% with a NH3 yield rate of 3.65 µg h−1 cm−2 at −0.4 V (vs RHE) in neutral electrolyte, which outperforms those of most Bi‐based NRR nanocatalysts. Noticeably, it also presents excellent electrochemical durability for at least 24 h. The present work provides a simple and effective strategy for designing low‐cost and high‐performance Bi‐based catalysts.

Power Law Creep Behavior Model of Third Generation Lead-Free Alloys Considering Isothermal Aging

Abstract In realistic applications, the solder joint is continually subjected to thermal-mechanical stress due to the difference in the coefficient of thermal expansion between the printed circuit board substrate and the electronic packaging components. Creep and fatigue processes were the most common causes of failure in electronic assemblies. Under isothermal aging, creep deformation becomes more prominent. The aged microstructure was recognized by intermetallic coarsening and the appearance of intergranular fracture generated by dynamic recrystallization in the bulk solder joint. In this study, the influence of Bi content on the creep behaviors of solder joints was investigated under various aging conditions. Three lead-free solder alloys, including SAC305, SAC-3Bi, and SAC-6Bi, are tested at room temperature. For each alloy, preliminary micro-indentation tests were conducted to define three stress levels for distinct aging conditions. After each test, displacement versus time data was gathered. A novel approach based on an empirical model was developed to systematically examine the development of the steady-state creep rate. A power dependency prediction model was developed to investigate the relationship between creep strain rate and stress levels. The steady-state creep rate of SAC305 is significantly higher than that of SAC-Bi alloys owing to the presence of bismuth (Bi) in the solid solution at room temperature. The creep properties showed less variation after 100 h of aging. SAC-Bi alloys showed less coarsening of the intermetallic compounds precipitates after aging than SAC305. In the SAC-Bi solder alloys, combinations of precipitate and solid solution hardening mechanisms were observed, while Ag3Sn particles were the dominant strengthening mechanism in the SAC305 alloy system.

High-strength joining of silica glass and 2024 aluminum alloy by ultrasonic-assisted soldering with Sn-Bi low temperature solder

To alleviate the problem of residual stress in silica glass/2024Al soldered joints, ultrasonic-assisted soldering of silicon glass and 2024Al was carried out using SnBi low-temperature solders. The impact of the soldering temperature and Bi content of the solder on the soldered joints were studied. Powder-reinforced solders were utilized to further improve the joint shearing strength, and the stirring time of the composite solder was also researched. The results showed that the joint strength stabilized after the soldering temperature reached 260 °C. For solders with different Bi content, the highest joint strength (27.3 MPa) was achieved with Sn28Bi solder. The composite solder could further increase the joint strength to 32.1 MPa. In addition, 10 min of ultrasonic vibration and mechanical stirring were recommended to obtain a high-quality composite solder.