Bismuth Doped Zinc Oxide Research Articles

Synthesis, characterization, and humidity sensing performance of polyaniline bismuth-doped zinc oxide (PANI-Bi-ZnO) composites

Synthesis, characterization, and humidity sensing performance of polyaniline bismuth-doped zinc oxide (PANI-Bi-ZnO) composites

Cadmium Sulphide Thin Film with ZnO:Bi Buffer Layer for Heterojunction Solar Cell Window Layer Applications

Solar cells need improved efficiencies to reduce electricity costs, which can be achieved through a window layer. Candidate window layer films were fabricated using CdS and bismuth doped zinc oxide (ZnO:Bi). Analyses on the structural, electrical and optical properties were conducted. CdS films with ZnO:Bi buffer layer displayed ohmic contact behavior, high conductivity and low resistivity. Optical properties showed wider band gaps (2.49 − 3.29 eV) than silicon (1.1 eV), low reflectance and high transmittance, in the visible light range, and refractive indices lower than Si. Results confirm that films made of CdS and ZnO:Bi can potentially improve solar cell efficiency.

Structural and Optical Properties of Bismuth-doped ZnO Nanoparticles Synthesized by Co-precipitation

Bismuth-doped zinc oxide (ZnO) nanoparticles can serve as efficient photocatalysts for various reactions. Herein, we synthesized and discussed the growth mechanisms of Bi-doped ZnO nanoflakes using co-precipitation with Bi concentrations ranging from 0 to 3 %. The resulting ZnO were hexagonal nanosheets with diameters ranging from 80 nm (ZnO) to 200 nm (ZnO: Bi 3%). The dominant crystal structure matches hexagonal wurtzite with a small presence of Bi2O3 diffraction peaks. The estimated crystallite sizes range from ~ 33 nm to ~ 45 nm, indicating multiple crystalline regions in each nanoflake. Nevertheless, as sheet resistance monotonically decreases with the Bi concentration, the higher number of grain boundaries likely has a lower effect on the conductivity compared to an increase in free carriers and larger grain size in the samples with higher Bi concentration. The bandgap decreases from ~ 3.13 eV to ~ 2.96 eV, likely due to the shrinkage effect from electron-electron or electron-impurity interaction that lowers the conduction band of ZnO.

Effect of varied number of multilayers, for cadmium sulphide with bismuth-doped zinc oxide buffer layer, on optical properties

Multilayer of Cadmium Sulphide (CdS) and Bismuth-doped Zinc Oxide (ZnO:Bi) is a direct band gap material, capable of use as a window layer material for silicon solar cells. With tuneable energy band gaps (2.41–2.71 eV)the ZnO:Bi/CdS window multilayer can allow for absorption of a wider range of wavelengths. This paper presents the varied number of ZnO:Bi/CdS multilayers and its effect on the optical properties. Samples were prepared using 3–11 layers of CdS and 3 layers of ZnO:Bi. Optical and structural properties were investigated through techniques including UV-Vis, XRD and FTIR analysis. Trends in energy band gaps were visible in relation to the number of layers used. The ZnO:Bi/CdS window layer demonstrated good absorption/transmission properties that make it a potential way of improving existing solar cell technology. Due to the high transmission rates, wavelengths of light (> Energy band gap of 1.1 eV) harnessed by Si cells, would not be hindered, while absorption of high energy photons (UV-Visible) can be improved on bulk Si solar cells.

Photo-Electrocatalytic Applications of Pure and Bismuth Doped Zinc Oxide Thin Films by Spray Pyrolysis

Photo-Electrocatalytic Applications of Pure and Bismuth Doped Zinc Oxide Thin Films by Spray Pyrolysis

Effect of the Physicochemical Modification on Bismuth-doped Zinc Oxide in the Anisotropic Orientation of Liquid Crystal Molecules

Alignment of liquid crystals by ion-beam (IB) irradiated bismuth-doped zinc oxide (BZO) films was investigated. The BZO alignment layer was deposited using a simple solution process, and IB irradiation of the BZO was used to induce surface-alignment of LC molecules uniformly. Solution-processed thin films have numerous advantages, including low manufacturing cost, simplicity of fabrication, and high productivity. IB irradiation of the BZO film induces a drastic improvement in the uniformity of the BZO surface and creates physico-chemical modifications that preserve the anisotropic characteristics of the surface, thereby unidirectionally aligning the LC molecules.

Soft template-based bismuth doped zinc oxide nanocomposites for photocatalytic depolymerization of lignin

Lignin depolymerization is a growing research area for the synthesis of aromatic molecules. In current studies, photocatalytic lignin depolymerization has been investigated by designing a series of soft template-based Zn0.95Bi0.05O nano-materials (SK1-SK5). Synthesized nano-materials were characterized by PXRD, SEM/EDX, BET, FTIR and utilized for photocatalytic lignin depolymerization in the presence of direct sunlight. Lignin depolymerization was monitored by UV–Visible Spectroscopy and catalytic pathway analyzed by different kinetic models. Percent depolymerization was studied for the effect of catalyst dose, starting lignin concentration and different temperatures. Pseudo second order was found the best fitted kinetic model indicating chemically rate controlled mechanism. Activation energy (Ea) for the reaction was found to be 11 kJ/mol that is remarkably lower than conventional lignin depolymerization i.e. 59.75 kJ/mol depicting better catalytic efficiencies of tested materials. Lignin depolymerization products were characterized by HPLC and FTIR Spectroscopy and their analysis indicated the conversion of lignin into smaller subunits like syringaldehyde, sinapyl alcohol, phthalates, and 4-hydroxy-benzoic acid. Specifically, phenol (21%) and 2-methoxy-4-methylphenol (16%) were detected by GCMS analysis in the products of lignin depolymerization by SK2.

Bi-doped ZnO yellow nanopigments: Synthesis, characterization, and antibacterial application for painting humid places

The main objective of the present study is the synthesis of yellow nanopigments with antibacterial properties that are suitable to paint humid places. Bismuth doped zinc oxide nanopigments were prepared through a gelatin based sol gel root. The nanopigment powders were obtained through the calcination of the prepared gels at 600 °C for 2 h. The synthesized samples were analyzed by x-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), and transition electron microscopy (TEM). The powder XRD investigations and TEM observations revealed wurtzite hexagonal structure with particle and crystalline sizes lower than 100 nm. The colorimetric properties were indicated by color space method. The achievements showed yellow color for the Bi-doped samples. The antibacterial effects of the prepared samples were observed by disk diffusion method against the gram positive (G+) bacteria Bacillus Subtilis (PTCC 1420) staphylococcus aurous (PTCC 1431) and gram negative (G-) pseudomonas aeruginosa (PTCC 1074) and Escherichia Coli (PTCC 1399) bacteria that grow normally in humid places. The results showed that the prepared yellow nanopigments are suitable candidate for painting humid places.

Structural, Electrical, and Optical Properties of Bismuth-doped Zinc-oxide Thin Films Grown by Radio-frequency Magnetron Sputtering

The effect of deposition temperature on the structural, optical, and electrical properties of bismuth-doped zinc-oxide (BZO) thin films was studied. The BZO thin films were prepared on sapphire substrates at various deposition temperatures by using radio-frequency magnetron sputtering. X-ray diffraction patterns showed a strong peak due to the (002) planes of Zinc-oxide (ZnO) for all samples, regardless of deposition temperature. As the deposition temperature increased, both the grain size and the film thickness increased. The optical transmittance (~ 80% at ~ 440 nm) increased rapidly with increasing wavelength and approached nearly 99% above the wavelengths of 800 nm. With increasing deposition temperature, both the electron concentration and mobility in the BZO thin films increased whereas the resistivity decreased. These results suggested that the deposition temperature is an important factor in determining the formation of high-quality BZO thin films on sapphire substrates.

Electrical tuning of spin splitting in Bi-doped ZnO nanowires

The effect of applying an external electric field on doping-induced spin-orbit splitting of the lowest conduction-band states in a bismuth-doped zinc oxide nanowire is studied by performing electronic structure calculations within the framework of density functional theory. It is demonstrated that spin splitting in Bi-doped ZnO nanowires could be tuned and enhanced electrically via control of the strength and direction of the applied electric field, thanks to the nonuniform and anisotropic response of the ZnO:Bi nanowire to external electric fields. The results reported here indicate that a single ZnO nanowire doped with a low concentration of Bi could function as a spintronic device, operation of which is controlled by applied lateral electric fields.

Hazardous o-toluidine mineralization by photocatalytic bismuth doped ZnO slurries.

Photocatalytic mineralization of o-toluidine in aqueous media under UV/solar irradiation was achieved by bare and bismuth doped zinc oxide nanoparticles. By adopting different analytical approaches a reaction mechanism is proposed, explaining the differences in photodetoxification performances.

Optical and electrical properties of Bi doped ZnO thin films deposited by ultrasonic spray pyrolysis

Undoped Zinc oxide (ZnO) and Bismuth doped zinc oxide (ZBO) thin films have been prepared by a simple and inexpensive technique namely ultrasonic spray pyrolysis. Films were prepared from an aqueous solution of zinc acetate on glass and silicon substrates at temperature of 350 °C. Doping is achieved by adding a small amount of Bi(NO3), H2O salt to the starting solution which is mixed thoroughly prior to spraying. The goal of this work is to study the influence of doping (Bi) with different concentrations on the structural, optical, and electrical properties of Bi doped ZnO films. Structural analysis shows that the ZBO layers are polycrystalline with a wurtzite structure and (100) preferential orientation which disappears gradually with increasing doping concentration. The optical transmittance average of all films, regardless the doping concentration, was higher than 80% in the visible range. The obtained films gaps values vary in the range from 3.19 to 3.24 eV and the Urbach energy lies in the range 11 to 530 meV. The measured conductivity, in dark and at room temperature, varies with four order of decade level (from 10−3 to 10+1 (Ωcm)−1)with increasing Bi doping level.

Grain Growth Behavior of Bi2O3‐Doped ZnO Grains in a Multilayer Varistor

A novel bismuth‐doped zinc oxide (ZnO) laminated structure is prepared in the present study. Seven layers with thickness ranging from 20 to 140 μm are laminated together with platinum (Pt) inner electrodes. The growth of Bi2O3‐doped ZnO grains within a very limited space between Pt electrodes is investigated. The grain growth behavior outside the confinement of electrodes is also studied for comparison purposes. At the beginning of sintering, a similar grain growth behavior is observed at different locations of the laminated structure. However, as sintering proceeds, the rate of grain growth within the Pt inner electrodes is decreased because of the decrease of available transportation paths. The grains between the electrodes then develop into a columnar shape as they make contact with the electrodes above and below them. Both the grain size and its distribution decrease with decreasing layer thickness.

Grain boundary structures in zinc oxide varistors

Lattice misorientations across electrically active interfaces in antimony and bismuth doped zinc oxide varistors have been determined by electron backscattered pattern analysis and coupled with the orientations of the associated grain boundary planes established by depth resolved electron beam induced current (EBIC) in order to index the crystal faces forming either side of the grain boundary plane. When correlated with the EBIC contrast observed at the grain boundary, it was found that a symmetrical EBIC profile was only found at interfaces where both crystal faces forming the grain boundary were oriented at a similar angle from the polar basal plane orientation. At the majority of grain boundaries the structure was such that one face lay close to the basal plane orientation with the other face much further away. In these cases the EBIC was suppressed on the side of the grain boundary whose face lay close to the basal orientation. The implications of these observations on the electrical structure of the interface and microstructural development are discussed.

Phase Transformations and Melting Effects During the Sintering of Bismuth‐Doped Zinc Oxide Powders

ZnO ceramics used as varistors are prepared with bismuth oxide as an essential additive. Some of its effects during the first step of liquid‐phase sintering remain unexplained. Therefore, in this work, we characterize the Bi distribution and identify the Bi‐rich phases in spherical Bi‐chemically‐doped ZnO powders. By a suitable method of differential thermal analysis conducted during sintering, we detect thermal phenomena. Characterization of ceramics quenched during sintering allows us to describe them and to analyze their influence on sintering. We also study the parameters which determine the occurrence of these events during sintering.