Bismuth Films Research Articles

Effect of acridine dye on the structure and magnetoresistance of electrochemically deposited polycrystalline bismuth films

Effect of acridine dye on the structure and magnetoresistance of electrochemically deposited polycrystalline bismuth films

A ratiometric electrochemical sensor for lead ions based on bismuth film coated porous silicon nanoparticles

A ratiometric electrochemical sensor for the detection of lead ions was developed based on porous silicon nanoparticles with in situ plated bismuth to improve the accuracy and reliability.

Determination of molybdenum(VI) via adsorptive stripping voltammetry using an ex‒situ bismuth screen‒printed carbon electrode

The development of a method for molybdenum(VI) determination in the presence of quercetin‒5′‒sulfonic acid (QSA) using a mercury‒free electrode is presented. Adsorptive stripping voltammetry is the electroanalytical technique used and an ex‒situ bismuth screen‒printed carbon electrode (BiSPCE) is the working electrode. The conditions for the bismuth film deposition were optimized and the different films were compared using field emission scanning electron microscopy. Different experimental parameters were optimized to obtain a sensitive, selective, and reproducible method. The best experimental parameters were: pH 5.8, ligand concentration: 30.0 µmol L−1; accumulation potential: −0.4 V, and accumulation time: 10 s. The detection and quantification limits obtained were 0.7 and 2.1 µg L−1, respectively. The linearity of the method was maintained in the range of 2.1 to 90.0 µg L−1. The possible interference of 36 foreign ions was studied. The method was validated with two certified water reference materials and synthetic seawater spiked with Mo(VI). The method was applied to determine the Mo(VI) concentration in tap water, groundwater, bottled mineral water, and seawater samples. The results were compared with measurements performed by an external analysis laboratory via ICP‒OES. The present work is an alternative method for molybdenum determination by an electroanalytical method, avoiding the use of mercury as electrode material. Additionally, the time required for sample analysis is fast due to the application of only 10 s in the accumulation step.

Tailoring the structural and optical properties of bismuth oxide films deposited by reactive magnetron sputtering for photocatalytic application

Bismuth oxide thin films were deposited by room temperature reactive magnetron sputtering of a bismuth target in different Ar/O2 atmospheres. The analysis of their structures and compositions shows that the films are formed of different phases depending on the oxygen flow rate (ՓO2). Films deposited at low ՓO2 consist of mixtures of crystalline metallic bismuth (Bio) and bismuth oxide phase (Bi2O3). Moreover, XPS analysis revealed the contribution of different oxidation states of bismuth related to Bio and Bi3+ in Bi2O3. The optical properties were investigated by spectroscopic ellipsometry and confirmed by UV–Vis spectroscopy. As ՓO2 increases above 1 sccm, bismuth oxide films become more transparent. They highly transmit light in the visible range, and the optical absorption edge shifts to short-wavelength such that the films exhibit higher bandgap values. Furthermore, the photocatalytic performance was determined upon comparing the degradation of 6.6 × 10−5 M of methyl orange (MO) under UV–Vis irradiation in the presence of different thin films. Results show that the low crystallinity, the improved optical absorption, as well as the existence of Bio in small proportion, increase the separation efficiency of the generated e−/h+ pairs inhibiting their recombination, thus enhancing the photocatalytic degradation of MO dye.

Towards jitter-free ultrafast electron diffraction technology

Stroboscopic visualization of nuclear or electron dynamics in atoms, molecules or solids requires ultrafast pump and probe pulses and a close to perfect synchronization between the two. We have developed a 3 MeV ultrafast electron diffraction (UED) probe technology that nominally reduces the electron bunch duration and the arrival time jitter to the subfemtosecond level. This simple configuration uses a radiofrequency photogun and a 90° achromatic bend and is designed to provide effectively jitter-free conditions. Terahertz streaking measurements reveal an electron bunch duration of 25 fs, even for a charge as high as 0.6 pC, and an arrival time jitter of 7.8 fs, the latter limited by only the measurement accuracy. From pump–probe measurements of photoexcited bismuth films, the instrument response function was determined to be 31 fs. This pioneering jitter-free technique paves the way towards UED of attosecond phenomena in atomic, molecular and solid-state dynamics. An ultrafast electron diffraction facility with an overall temporal resolution of 31 fs root mean square is developed. Even for a charge as high as 0.6 pC, the electron bunch duration and timing jitter are 25 fs and less than 10 fs, respectively.

Packaging of Ultrathin Flexible Magnetic Field Sensors With Polyimide Interposer and Integration in an Active Magnetic Bearing

Ultrathin sensors enable various scopes for measuring signals in restricted geometries. One example is the use of magnetic field sensors in active magnetic bearings (AMBs). Here, the thin sensor will allow measuring the magnetic flux directly in the air gap between the rotor and the stator of the AMB, which allows controlling the AMB faster and more precisely. This also results in a higher stiffness of the AMB. Therefore, the sensor has to be thinner than $150~\mu \text{m}$ . In this article, previous experiences with polyimide- and silicon-based Hall sensors which rely on thin bismuth films were used to realize a reliable sensor with suitable interconnection technologies. Especially the adhesive flip-chip technology, which was used with silicon interposers, has to be adapted and optimized for the packaging of polyimide-based sensors. The technologies and the materials were optimized for this approach with a special test design setup. Afterward, the working sensor systems were manufactured. These sensors show very promising results and could be successfully integrated into an AMB setup for preliminary tests.

Behavior of nanocomposite consisting of manganese ferrite particles and atomic layer deposited bismuth oxide chloride film

Nanocomposites of manganese ferrite and bismuth oxide chloride were synthesized. The composites consisted of 10 nm thick nanocrystalline bismuth oxide chloride thin film grown by atomic layer deposition on spinel MnFe2O4 nanoparticles prepared by wet chemical synthesis. The composite layers exhibited nonlinear polarization behavior in both magnetic and electric fields at room temperature. The magnetic coercive force, HC, was 30–40 Oe at room temperature. The width of electrical charge – voltage hysteresis loop reached 3.6 MV/cm.

Simultaneous voltammetric analysis of tryptophan and kynurenine in culture medium from human cancer cells

The paper outlines the first report of application of a differential pulse voltammetry for simultaneous quantification of clinically important molecular markers – tryptophan and its metabolite – kynurenine. The analytes were determined in less than 60 s at the boron-doped diamond electrode modified in situ with bismuth film (BiF/BDDE). Proper adjustment of a supporting electrolyte composition allowed to obtain good separation of tryptophan and kynurenine oxidation peaks that appeared at potential of 0.88 and 1.05 V (vs. Ag/AgCl), respectively. Studies using an optical profilometer have confirmed an increase in electrode surface area after deposition of Bi film. At the optimized conditions, the obtained detection limits of tryptophan and kynurenine were at 30 nM concentrations. The method was validated for linearity, precision, accuracy, selectivity and recovery. We have investigated an impact of numerous relevant interfering organic compounds (including amino acids and different tryptophan metabolites of kynurenine pathway) on voltammetric signals of the measured analytes. Finally, for proof˗of˗technology, the sensor was used for tryptophan and kynurenine quantification in culture medium collected from human cancer cell lines (breast MDA–MB–231 and ovary SK–OV–3). The target molecules were analyzed directly, without any sample preparation step. The sensor showed good accuracy in presence of the sample matrix components that was confirmed by high performance liquid chromatography measurements. Our work emphasizes the advantages of application of the herein proposed, easy to fabricate voltammetric sensor, instead of popular chromatographic assays or previously proposed potentiometric immunosensor. The method might serve for rapid assessment of kynurenine pathway activity in cancer cells.

Dynamics and manipulation of ferroelectric domain walls in bismuth ferrite thin films.

Ferroelectric domain walls differ from domains not only in their crystalline and discrete symmetry, but also in their electronic, magnetic, and mechanical properties. Although domain walls provide a degree of freedom to regulate the physical properties at the nanoscale, the relatively lower controllability prevents their practical applications in nano-devices. In this work, with the advantages of 3D domain configuration detection based on piezoresponse force microscopy, we find that the mobility of three types of domain walls (tail-to-tail, head-to-tail, head-to-head) in (001) BiFeO3 films varies with the applied electrical field. Under low voltages, head-to-tail domain walls are more mobile than other domain walls, while, under high voltages, tail-to-tail domain walls become rather active and possess relatively long average lengths. This is due to the high nucleation energy and relatively low growth energy for charged domain walls. Finally, we demonstrate the manipulation of domain walls through successive electric writings, resulting in well-aligned conduction paths as designed, paving the way for their application in advanced spintronic, memory and communication nano-devices.

Structural Surface Features of Tellurium-Doped Bismuth Films

The effect of the degree of tellurium doping on the structural characteristics (average sizes of grains and growth figures) of bismuth films in the concentration range 0.005−0.15 at % Te and the thickness range 0.3−0.7 μm is studied. The thicknesses of the investigated films are measured by multi-beam optical interferometry. The amount of tellurium in the film is considered to be equal to that in the initial bismuth single crystal with a previously known tellurium concentration. Additional control of the tellurium content in the initial crystal is performed using a time-of-flight LYUMAS-30 mass spectrometer. To determine the average sizes of grains and growth figures, I use the technique developed by E.V. Demidov. The studies conducted reveal that an increase in the degree of tellurium doping in bismuth films leads to a significant decrease in the growth figures. The weak effect of annealing on the crystallite size in tellurium-doped bismuth films indicates the high temporal stability of their structures.

Sensor Fabrication for Determination of Cadmium Using Nafion/Ionic Liquid/Graphene Composite with Thick Film Technology

The cadmium (Cd (II)) detection sensor consists of working electrode, counter electrode and reference electrode made with thick film technology on sensitive material-based carbon electrodes (G/N/IL/SPCE) and coated with Bismuth film. Carbon (C) paste, Ag | AgCl is used as working electrode, counter electrode and reference electrode material on alumina substrate by screen printing. The working electrode was doped with Graphene (G), Nafion (N) and Ionic liquid (IL). Furthermore, Bismuth-Film (BiF) is coated with electrodeposition on the surface of the working electrode. Electrode characterization with SEM is conducted to see the morphology of sensitive materials. It showed that the particles were distributed evenly on the surface of the electrode with spherical particles. Analysis using EDS shows the element’s atomic composition is C 91.57%, N 3.48%, O 3.23%, Bi 0.01%. The performance of the cadmium sensor was tested with a potentiostat in a standard Cd solution with a concentration of 0.005 mgL-1 – 1 mgL-1 indicating an average output voltage range of 10.36 volts - 10.37 volts. This can be explained that the sensor can detect Cd (II) content properly according to performance.

Nanoscale films of bismuth and antimony: production technologies and properties

We studied the line of bismuth and antimony thin films obtained by thermal evaporation with or without additional annealing or zone recrystallization under a coating. The dependence of film structure on the production technology and substrate type has been shown. The dependence of galvanomagnetic properties of thin films on the structure has been investigated.

Effects of Humidity, Temperature and Bismuth Electrodeposition on Electroanalytical Performances of Nafion‐coated Printed Electrodes for Cd2+ and Pb2+ Detection

AbstractThe synergistic use of Nafion polymeric membrane and in situ electrodeposited bismuth film is a worthwhile strategy to develop electrochemical sensors for the detection of Cd2+ and Pb2+. However, Nafion thin films morphological and conductivity properties have a strong dependence on the environmental conditions, such as relative humidity and temperature, while the bismuth in situ electroplating can affect the repeatability of measurements. With the aim to overcome these drawbacks, the effects of the storage environmental conditions were investigated to improve the morphological stability and electroanalytical performances of Nafion film‐based sensor for the detection of Cd2+ and Pb2+. Nafion‐coated graphite‐based screen‐printed electrodes were stored at different humidity and temperature conditions and characterised by using square wave anodic stripping voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. Significant differences were observed at the varying of humidity conditions, with an enhancement of sensor electrochemical performances at lower humidity. Furthermore, different approaches for bismuth in situ electrodeposition on Nafion‐coated screen‐printed electrodes were compared by using overlap or removal approach. This study disclosed considerable differences in the electrochemical performances and morphology of the resulting bismuth‐sensor, obtaining an enhancement of the working stability for the removal approach.

Voltammetric screen-printed carbon sensor modified with multiwalled carbon nanotubes and bismuth film for trace analysis of thallium(I)

Voltammetric screen-printed carbon sensor modified with multiwalled carbon nanotubes and bismuth film for trace analysis of thallium(I)

Stabilization of the β-phase Bi2O3(201) thin film by an ultrathin Bi(001) seeding layer

The bismuth oxide films prepared by the physical evaporation of Bi2O3 or the thermal oxidation of Bi usually display amorphous or ploycrystalline structures. There has been only few reports on the fabrication of the pure β-phase Bi2O3 film which is accomplished under extreme conditions. In this study, an innovative method is introduced to fabricate the β-phase Bi2O3 film with (201) preferred orientation by utilizing an ultrathin Bi(001) seeding layer. The Bi/BiOx bylayers were prepared at room temperature first and then annealed in oxygen ambient. The formation of (201) orientation of Bi2O3 film was strongly related to the oxygen pressure during annealing. Compared with the bismuth oxide obtained directly from the thermal oxidation of the bismuth film, the β-phase Bi2O3(201) film displayed a smooth surface and well crystallinity.

Epitaxial Growth of Free-Standing Bismuth Film on Graphene Embedded with Nontrivial Properties

Topological insulators (TIs) have become one of the intensely pursed topics during the past few years due to their robust gapless edge states, among which bismuth (Bi) enjoys a good reputation because of its rich quantum states. However, bulk Bi itself is topologically trivial. While thin Bi film has long been theoretically perceived to be a two-dimensional topological insulator, it still remains a challenge to construct free-standing Bi(111) film experimentally. Herein, we investigate the epitaxial growth of bismuth films on graphene with the film facet ranging from (110) to (111) with increasing coverage and demonstrate the topologically nontrivial property embedded in Bi(111) layers by angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations. In contrast to the bulk Bi with semimetallicity, a metallic surface state is revealed in the 7-bilayer Bi(111) with a circle-shape photoemission intensity plot, while the stacking of free-standing bismuth bilayers on graphene is rationalized to be responsible for the nontrivial characteristics of Bi(111) with an odd crossing of the Fermi level. Our report herein proposes an intriguing approach toward fabricating topologically nontrivial bismuth film, as well as advancing the fundamental understanding of Bi(111) bilayers. Importantly, the combination of the nontrivial Bi(111) film and graphene might also shed useful insights into the development of nanotronics and spintronics.

Fabrication and physical properties of bismuth layer-structured ferroelectric thin films with c-axis orientation epitaxially grown by high-temperature sputtering

Highly c-axis oriented (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT) thin films were deposited on the Pt(100)/MgO(100) substrates by high-temperature sputtering. The substrate temperature was varied from 550 °C to 650 °C to examine its effect on the structural, dielectric, ferroelectric, and piezoelectric characteristics of the films, and consequently find the optimal substrate temperature for heteroepitaxial growth of BNEuT thin films. All the films deposited at 580 °C–650 °C exhibited a high degree of c-axis orientation [α(00l)] of ≥97%. All the films grown heteroepitaxially on Pt(100)/MgO(100) substrates was rotated by ±45° with respect to the underlying substrates and had a mainly upward polarization, based on data observed by piezoresponse force microscopy. Judging from the structural, dielectric, ferroelectric, and piezoelectric characteristics, it is shown that the optimal substrate temperature for heteroepitaxial growth of BNEuT films with a high α(00l) of >97% and a comparatively large remanent polarization of 2.0 μC cm−2 is 580 °C.

A sensitive electrochemical sensor for simultaneous voltammetric sensing of cadmium and lead based on Fe3O4/multiwalled carbon nanotube/laser scribed graphene composites functionalized with chitosan modified electrode

In this work, based on a Fe3O4/multiwalled carbon nanotube/laser scribed graphene composites functionalized with chitosan modified glassy carbon electrode (Fe3O4/MWCNTs/LSG/CS/GCE), a highly active, sensitive, facile and low-cost electrochemical sensor was fabricated to determine cadmium (Cd2+) and lead (Pb2+) simultaneously using square wave anodic stripping voltammetry (SWASV). This novel nanocomposite possessed a significantly large specific area, remarkably high conductivity and excellent absorption ability. By in situ plating bismuth film, this constructed sensor proved favorable electrochemical response with a wide linear range from 1 to 200 μg L−1, and an ultralow detection limit of 0.1 and 0.07 μg L−1 for Cd2+ and Pb2+ (S/N = 3), respectively. Furthermore, excellent repeatability, reproducibility, stability, and reliable practical applicability were achieved in the constructed sensor. Finally, the prepared sensor is believed to provide promising applications in the electrochemical determination of heavy metal ions.

Voltammetry Determination of Pb(II), Cd(II), and Zn(II) at Bismuth Film Electrode Combined with 8-Hydroxyquinoline as a Complexing Agent.

A novel method was developed for the simultaneous determination of Pb(II), Cd(II), and Zn(II) based on the cathodic stripping response at a bismuth film electrode associated with oxine as a chelating agent. The developed method provided a high and sharp electrochemical response compared with the method without oxine. A linear response of peak currents was observed for Pb(II), Cd(II), and Zn(II) concentration in the range from 2 ppb to 110 ppb. The detection limits of Pb(II), Cd(II), and Zn(II) were 0.45, 0.17, and 0.78 ppb, respectively. This method was successfully applied to the determination of Pb(II), Cd(II), and Zn(II) in lake-water and river-water samples. The metals were detected at the ultratrace level, showing the feasibility of the proposed method for environmental applications.

Solid-Phase Interaction in Fullerite-Bismuth Films in the Process of Thermal Annealing

The changes in the structure, surface roughness, and phase composition of thin fullerite-bismuth films deposited onto substrates from oxidized single-crystal silicon under thermal action in vacuum are studied by means of atomic-force microscopy and X-ray diffraction analysis. It is established that as-deposited bismuth films have a polycrystalline structure in the form of thin plates with an average arithmetic surface roughness of 13.72 nm. The thermal annealing of films at 490 K results in fractional recrystallization of the films and a decrease in the average arithmetic roughness to 12.74 nm. After thermal action at 540 K, the average arithmetic roughness of the films is 10.32 nm, the crystallites take the form of globules with an average size of 100 nm, new X-ray reflections appear on the X-ray patterns that indicate the formation of bismuth fulleride.