Effects Of Dopant Content Research Articles

Molecular Dynamics Investigation of Metastable Structure and Hybridization Bond Evolution in High-Entropy CoCrFeNi Heterostructured Amorphous Carbon Films.

Heterogeneous element doping in amorphous carbon films can reduce residual stresses and improve plastic deformation. Nevertheless, the effects of dopant content and size on the metastable transition mechanism between sp2-C and sp3-C atoms during the deformation process are unclear and difficult to be in situ observed and researched, experimentally. In this work, the mechanical properties and the structural evolution during the nanoindentation of amorphous CoCrFeNi sphere-doped carbon heterostructured films with different radii were simulated. The results indicate that the hardness H and elastic modulus E of the films decreased with the increase of the dopant addition. H decreases from 50.69 to 28.94 GPa, and E decreases from 664.39 to 448.62 GPa. The decrease in the elastic recovery and the enlargement of the shear transition zones indicate that the presence of the amorphous CoCrFeNi dopant can significantly improve the plastic deformation capacity of the films. During the nanoindentation process, the spherical dopants reduce the stress and shear strain of the regions under the indenter in a-C films. The reduction of compressive and shear stresses in the film can inhibit the C atom metastable transition from sp2-C to sp3-C. This can provide a theoretical basis for the development and design of heavy-load and high-deformation-rate a-C films.

Nb (V, Nb/V)-Doped TiO2 Films as New Transparent Conducting Oxides Synthesized by a Novel ALD Process: Effect of Dopant Content and Growing Conditions

Titanium oxide (TiO2) is a wide bandgap (3.0-3.4 eV) material that presents a high transparency in the visible range, a high refractive index, and an insulator behavior. In order to vary its structural, optical, and electronic properties with the objective to synthesize transparent conductive oxide (TCO) films, we have investigated several doping strategies. Due to their extra electron and atomic radius close to that of Ti, respectively larger for Nb or smaller for V, these are among the interesting potential dopants of TiO2. In this objective to synthesize TiO2-based TCO films, we have performed atomic layer deposition (ALD) with different concentrations of Nb dopants and by varying the growth conditions.Highly transparent and conducting Nb-doped TiO2 thin films were produced by a low-temperature (300 °C) new ALD process using titanium tetraisoproxide, niobium(V) ethoxide, and water as a reagent. The deposition was performed in a supercycle fashion, alternating Ti precursor and water cycles followed by Nb precursor and water cycles, which allowed controlling the dopant concentration. This study focused on non-annealed and annealed films under N2 and forming gas. The dopant concentration significantly affected the fabricated films' thickness, structure, morphology, composition, and optical and electrical properties. Indeed, the crystalline anatase phase was obtained before annealing for a low Nb content, while the films were found amorphous for a larger Nb content. The non-annealed film thickness and surface roughness decreased with increasing Nb doping, while the size of the anatase grains increased, and the films became amorphous. This progressive amorphization of the films with increasing Nb content was observed by several techniques (G-XRD, Raman, and FTIR). Surprisingly, films annealed at 600°C led to the formation of larger and more homogeneous grains than for non-annealed films. Moreover, the XRD, Raman, and FTIR results clearly indicated the substitution of Ti by Nb in the anatase structure. Furthermore, the XPS spectra showed that the amount of Ti and Nb in the Ti3+ and Nb4+ oxidation states increased with increasing the Nb content. These two latter points may explain the decrease in resistivity caused by the increase of density of shallow donor states in addition to the decrease of electrons scattering caused by the grain size increase. In addition, the film transmittance was increased up to 15% while the resistivity decreased to 10-3 Ω.cm leading to a TCO behavior. Using the figure of Merit (FoM) established over a wide spectral range from AM1.5g irradiance [*] giving the maximum photocurrent density of an ideal solar cell equipped with such TCO electrode, it showed an improvement by a factor of 8 by Nb doping, reaching a maximum of FoM for the film produced with a particular Nb doped rate of 0.33.Other strategies of TCO improvement were investigated, such as growing V-doped, and Nb&V co-doped TiO2 films by innovative dual and triple precursors ALD processes, respectively. Once more, the dopant kind and amount strongly impacted the growth rate, structure, morphology, optical and electrical properties of those two new kinds of doped TiO2 materials. The full study of Nb-doped TiO2 films will be presented, while the comparative results obtained for V-doped and Nb/V-doped materials will be introduced.The Nb-doped TiO2's TCO performances and future improvement based on V-doped, and Nb&V co-doped may pave the way for the use of those kinds of materials in solar radiation energy conversions as electrode or junction materials for Photovoltaic or photo(electro)catalytic systems.[*] J.A. Mendez-Gamboa, R. Castro-Rodriguez, I. V. Perez-Quintana, R.A. Medina-Esquivel, A. Martel-Arbelo, A figure of merit to evaluate transparent conductor oxides for solar cells using photonic flux density, Thin Solid Films. 599 (2016) 14–18. https://doi.org/10.1016/j.tsf.2015. .12.038. Figure 1

Preparation and Characterization of Al-doped Tantalum Nitride Thin Films: Effect of Dopant Content and Film Thickness

Preparation and Characterization of Al-doped Tantalum Nitride Thin Films: Effect of Dopant Content and Film Thickness

The Effects of Manganese Dopant Content and Calcination Temperature on Properties of Titania-Zirconia Composite

The effects of dopant content and calcination temperature on Mn-doped TiO2-ZrO2 structure and properties were successfully investigated. Composite of Mn-doped titania-zirconia was synthesized by sol-gel method. Titanium(IV) isopropoxide was used as the precursor of TiO2, while zirconiapowder was used as another semiconductor. MnCl2∙4H2O was used as the source of dopant in this study. Various amounts of manganese were incorporated into TiO2-ZrO2 and calcination was performed at temperatures of 500, 700 and 900 °C. Synthesized composites were characterized by Fourier-transform infrared spectroscopy (FTIR), specular reflectance UV-Vis spectroscopy (SR UV-Vis), X-ray diffraction method (XRD) and scanning electron microscopy equipped with X-ray energy dispersive spectroscopy (SEM-EDX). The results showed that Mn-doped TiO2-ZrO2 with the lowest bandgap (2.78 eV) was achieved with 5% of Mn dopant and calcined at 900 °C, while Mn-doped TiO2-ZrO2 with the highest bandgap (3.12 eV) was achieved with 1% of Mn dopant content calcined at 500 °C.

In-situ synthesis of Fe and O co-doped g-C3N4 to enhance peroxymonosulfate activation with favorable charge transfer for efficient contaminant decomposition

Iron and oxygen co-doped graphite phase carbon nitride (Fe@OCN) is synthesized via a simple one-pot in-situ pyrolysis method. It is used in a favorable peroxymonosulfate (PMS) activation oxidation system to enhance Orange I (OI) degradation. The effects of dopant contents, different water conditions and the reusability are conducted to evaluate the removal efficacy of PMS catalytic over Fe@OCN in water. Moreover, OI degradation is almost stable under several typical anions (H2PO4−, Cl− and HCO3−) and humic acid existence. Theoretical calculation results reveal that effective-directional transfer of electrons is obtained by Fe@OCN, building the formation of high electron density areas around Fe and O. The quenching tests display that O2•− and 1O2 are responsible for OI removal, and SO4•− and •OH only donate a very small contribution. The electron transfer between electron-rich Fe, O element and HSO5− cycles facilitate HSO5− activation to generate reactive oxygen species. After co-doping, DFT calculations confirm the stronger binding energy, greater charge transferability and longer OO bond length for PMS activation in Fe@OCN/PMS system. Our findings provide a valuable insight for the development of efficient catalysts for PMS activation via metal and nonmetal co-doping, which display a promising application for polluted aquatic environment.

Preparation of lanthanum silicate electrolyte with high conductivity and high chemical stability

Effects of dopant content and synthesis temperature on phase relations and conducting behavior of lanthanum silicate, La9.33+xSi6O26+1.5x (LSO) electrolytes were investigated. The La-excess-type Fe-doped LSO, La10(Si5.5Fe0.5)O26.75 synthesized at 1973 K showed lower grain boundary as well as grain interior resistances, and then, had high total conductivity (6.9 × 10−3 S cm−1 at 873 K and 3.6 × 10−5 S cm−1 at 573 K). In addition, the chemical instability owing to a high lanthanum activity in the La-excess-type LSO (x = 0.67) specimen could be eliminated by incorporating iron into the specimen. The synchrotron radiation microbeam X-ray diffraction technique revealed that this specimen contains a small amount of new secondary phase, which differs from the situation found in a highly conductive but chemically unstable Al-doped LSO specimen with the same x value and the same synthesis temperature.

Sequentially Deposited Antimony-Doped CH3NH3PbI3 Films in Inverted Planar Heterojunction Solar Cells with a High Open-Circuit Voltage

We introduce antimony-doped hybrid perovskite compounds in planar inverted solar cells. Here, we report in-depth and systematic studies on the formation of the perovskite layer through a modified two-step spin-coat method. In this method, the “loading time” of CH3NH3I on a “wet” PbI2 layer was varied in achieving a complete conversion to the perovskite material. The “loading time” that in turn also controlled morphology of the perovskite layer along with the antimony content in perovskite compounds was varied to optimize the solar cell performances. The effect of dopant content has affected the band diagram, which was drawn from density of states of the components as derived from their scanning tunneling spectroscopy. The solar cell parameters were then correlated with the experimental band diagram of the heterojunctions. In Cu@NiO|CH3NH3Pb0.92Sb0.08I3|PCBM p–i–n heterojunctions, we have achieved a high open-circuit voltage of 1.13 V with an energy conversion efficiency of 12.8%. The solar cell parameters have been correlated with junction properties, which have been studied through in-depth analysis of diode characteristics.

Kinetic modeling of sonocatalytic performance of Gd-doped CdSe nanoparticles for degradation of Acid Blue 5

CdSe and Gd-doped CdSe nanoparticles were synthesized using a simple hydrothermal method, and their catalytic activity was examined toward degradation of Acid Blue 5 (AB5) in the sonocatalytic process. The structure and morphology of as-prepared nanomaterials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Branauer, Emmett and Teller (BET) and Fourier infrared spectroscopy (FT-IR) techniques. Among the synthesized samples, 4% Gd-doped CdSe nanoparticles demonstrated the highest catalytic activity with band gap energy of 1.61eV. The effect of dopant content, initial dye concentration, catalyst dosage, ultrasonic power and inorganic radical scavengers on the degradation efficacy of AB5 was evaluated. The produced intermediates of AB5 degradation during sonocatalytic process were verified using gas chromatography–mass spectroscopy (GC–MS) technique. A novel intrinsic kinetic model for prediction of AB5 degradation efficiency was proposed. A good agreement was obtained between developed model and experimental data (R2>0.94).

High-performance pure and Fe3+-ion doped ZnS quantum dots as green nanophotocatalysts for the removal of malachite green under UV-light irradiation

The heterogeneous photocatalysis using UV-radiation and quantum dots (QDs) is an interesting method for the treatment of water polluted with the organic substances. In this study, ZnS QDs, as a pure and doped with Fe3+, were prepared for photodecolorization of malachite green (MG) as a model dye. The synthesis of QDs was carried out using a chemical precipitation method in aqueous solution, in the presence of 2-mercaptoethanol as a capping agent. The XRD patterns indicated that the doped nanoparticles are crystalline, with cubic zinc blend structure. The effects of dopant content, pH, nanophotocatalyst amount, irradiation time, and initial dye concentration on the removal efficiency of MG were studied. Results showed that the QDs presented high MG decolorization efficiency, and doping with Fe3+ promoted the dye removal. The maximum removal of dyes was obtained at 80mg/L of photocatalyst as an optimum value for the dosage of photocatalyst in pH of 8.0.

Effects of dopant content on optical and electrical properties of In2O3: W transparent conductive films

The In2O3: W (IWO) films with different W content were deposited on glass substrate using direct current sputtering method. The structure, surface morphology, and optical and electrical properties were investigated. Results showed that both the carrier concentration and carrier mobility were increased with the doping of W. The IWO film with the lowest resistivity of 1.0×10−3 Ω·cm, highest carrier mobility of 43.7 cm2·V−1·s−1 and carrier concentration of 1.4×1020 cm−3 was obtained at the content of 2.8 wt.%. The average optical transmittance from 300 nm to 900 nm reached 87.6%.

Relation between Seebeck Coefficient and Lattice Parameters of (Ca2−y Sr y CoO3) x CoO2

The effect of dopant content on the Seebeck coefficient of the Sr2+-doped (Ca2−ySryCoO3)xCoO2 (y = 0 to 0.4) system was investigated. This system can be described as a misfit layered structure of (CoO2) and (Ca2−ySryCoO3) layers, which have different b lattice parameters denoted by b1 and b2, respectively. Due to the solubility limit of Sr in (Ca2CoO3)xCoO2, systematic investigations were available only up to y = 0.2. Nevertheless, the structural uniqueness enabled partially quantitative analysis of the correlation between the crystal structure and Seebeck coefficient of the system. Substitution of Sr for Ca leads to lattice expansion which accompanies an anisotropic change of the lattice parameters. Among the lattice parameters considered, the increase in the lattice parameter b2 of the insulating layer was larger than the change of any other lattice parameter, which induced in-plane stress in the conducting layer. As a result, as the b1/b2 misfit ratio of (Ca2−ySryCoO3)xCoO2 is decreased, the Seebeck coefficient also decreases. Practical guidance for selecting dopants to enhance thermoelectric performance is proposed.

Improving humidity sensing properties of nanoporous TiO 2–10 mol% SnO 2 thin film by co-doping with La 3+ and K +

La 3+ and K + co-doped nanoporous TiO 2–10 mol% SnO 2 thin films have been prepared by sol–gel method with Pluronic P123 as the organic template on alumina substrates, and their humidity sensing properties have been investigated. It was found that the addition of rare earth ion La 3+, alkali ion K + and tri-block copolymer Pluronic P123 is beneficial for improving the humidity sensitive properties of the samples. The sensing behaviors of thin films were inspected at different sintering temperatures by constructing a humidity-impedance measuring system. It is found that nanoporous TiO 2–SnO 2 doped with 0.3 mol% La 3+ and 50 mol% K + sintered at 500 °C for 4 h shows the best humidity sensing properties. This thin film achieves a high sensitivity with the impedance changed five orders of magnitude from 10 9 Ω to 10 4 Ω with excellent linearity in the relative humidity (RH) range of 11–95% at 25 °C. The response and recovery time of this thin film are about 11 and 18 s, respectively. High sensitivity, narrow hysteresis loop, rapid response and recovery, prominent stability and good reproducibility are obtained. The effects of dopant content on humidity sensitivity have also been discussed in terms of segregation of rare earth ions at grain boundaries and granularity of crystals, and influence of K + on the decrease in the intrinsic resistance of the materials and direct contribution to the conduction.

Humidity sensing properties of La 3+ and K + co-doped Ti 0.9Sn 0.1O 2 thin films

The humidity sensing properties of La 3+ and K + co-doped Ti 0.9Sn 0.1O 2 thin films were investigated. The humidity sensitive thin ?lms were prepared by sol-gel method on alumina substrates. The sensing behaviors of thin ?lms were inspected at different sintering temperatures by constructing a humidity-impedance measuring system. It was found that the addition of rare earth ion La 3+ and alkali ion K + was beneficial for improving the humidity sensitive properties of the samples and La 0.003K 0.5Ti 0.9Sn 0.1O 2 sintered at 500 °C for 4 h showed the best humidity sensing properties. The impedance of this thin ?lm decreased from 10 9 to 10 4 Ω with excellent linearity in the humidity range of 11%–95%. Narrow hysteresis loop, prominent stability and high sensitivity were obtained. The effects of dopant content and doping mechanism on humidity sensitivity were also discussed in terms of segregation of rare earth ions at grain boundaries and granularity of crystalline and influence of K + on the decrease in the intrinsic resistance of the materials, and increase in the number of water adsorption sites.

Synthesis, characterization and evaluation of PrBaCo 2− xFe xO 5+ δ as cathodes for intermediate-temperature solid oxide fuel cells

Iron doped layered structured perovskites, PrBaCo 2− x Fe x O 5+ δ ( x = 0, 0.5, 1.0, 1.5 and 2.0), are evaluated as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The effects of dopant content are investigated on their structural and electrochemical properties including crystalline structure, oxygen nonstoichiometry, stability in presence of CO 2, compatibility with electrolytes, thermal expansion coefficient, electrical conductivity, and cathodic interfacial polarization resistance. The lattice parameter and oxygen nonstoichiometry content, δ, at room temperature increase, whereas the conductivity, thermal expansion coefficient, and cathodic performance decrease with increasing iron content, x. PrBaCo 2− x Fe x O 5+ δ exhibit excellent stability at 700 °C in atmosphere consisting of 3% CO 2 and 97% air, show good chemical compatibility with doped ceria electrolytes at 1000 °C, but react readily with yttria-stabilized zirconia at 700 °C. Even with a Co-free PrBaFe 2O 5+ δ as the electrode, a symmetrical cell demonstrates area specific resistance of 0.18 Ω cm 2 at 700 °C with samaria-doped ceria electrolyte. The resistance is lower than those for typical Co-free electrodes reported in the literatures, suggesting that PrBaCo 2− x Fe x O 5+ δ are potential promising cathode materials for IT-SOFCs.

Structure and properties of selenious acid doped polyaniline with varied dopant content

In this study, the effects of dopant content on the structure, especially crystalline structure, and properties of selenious acid doped polyaniline (PAni) were investigated. The structure and properties of PAni were characterized by X-ray diffraction, FTIR spectroscopy, UV–vis spectroscopy, DSC, and TGA. By varying the dopant/monomer molar ratio (D/M), the morphology as well as the crystalline structure of PAni was significantly changed. The presence of water in the crystalline structure of PAni prepared with a low D/M ratio caused a change in the d-spacing of the PAni crystalline structure. The oxidation level and doping degree of PAni were also changed by varying the D/M ratio. The electrical conductivity of PAni increased with increasing D/M ratio, and the thermal stability of PAni in the doped state was about 200 °C for different D/M ratios.

Si-doped mesoporous TiO 2 continuous fibers: Preparation by centrifugal spinning and photocatalytic properties

TiO 2 continuous fibers were prepared by a sol–gel method combined with centrifugal spinning without any template or binder polymer. The fibers were characterized using XRD, FT-IR, SEM, N 2 adsorption–desorption, and UV–vis DRS. The addition of silica was a crucial factor for obtaining long fibers because of the formation of Ti–O–Si networks. The effects of dopant contents and heat treatment temperatures were studied. It was found that the proper addition of silica into titania could improve the surface texture and enhance the thermal stability and crystal stability. When Si/Ti molar ratio was 0.15, mesoporous TiO 2 fibers with a BET surface area up to 127.7 m 2 g −1 were obtained after heat treatment at 700 °C. It displayed the highest photoactivity of all, and the degradation rate of X-3B in aqueous solution reached 99.6% after 75 min under UV irradiation. Furthermore, the degradation rate and the mineralization rate of X-3B were 94.7% and 58.9% after 3 h under solar irradiation, respectively. In addition, it was worthwhile to mention that the degradation efficiency was also more than 90% after 6 cycles.

Humidity sensitive properties of K+-doped nanocrystalline LaCo0.3Fe0.7O3

This paper reports the study of humidity sensitive properties of pure and K+-doped LaCo0.3Fe0.7O3 thick film sensors. The humidity sensitive thick films were prepared by screen printing on ceramic substrates with interdigitated electrodes. It was found that pure LaCo0.3Fe0.7O3 showed sensitivity only in the relative humidity (RH) above 54%. The addition of alkali ion K+ was beneficial for improving the humidity sensitive properties of the sample. The best results were obtained for 2 wt.% K2CO3-doped sample, which exhibited excellent linearity in the whole humidity range of 11–95%. A resistance variation of about four orders of magnitude, narrow hysteresis loop, and rapid response were obtained. The effects of dopant content on humidity sensitivity were also discussed.

Low Temperature Degradation of Yttria Stabilized Zirconia

This paper explores the effects of dopant content on the aging behavior of tetragonal zirconia polycrystal (TZP). TZP powders with varying Y2O3 content (1.75-3mol%) were synthesized by co-precipitation. After the green body of as-prepared TZP powders being isostatically pressed at 200 MPa and sintered at 14000C for 3 h in air, a range of TZP ceramics were fabricated. As-synthesized TZP ceramics annealed at relatively low temperatures with the presence of water or water vapor. XRD analysis was conducted for phase identification and determined a tetragonal to monoclinic transformation. Microscope imaging displayed the changes of aged TZP surface structure. It is believed that the degradation of TZP might be caused by the reaction between Y2O3 and H2O. The mechanism of low temperature degradation of TZP was discussed.

UV and electron radiation-induced luminescence of Cu- and Eu-doped lithium tetraborates

Cu- and Eu-doped Li 2B 4O 7 has been characterized using steady-state and time-resolved photoluminescence, radioluminescence and optical absorption techniques. The effect of dopant content (7.0×10 −4–5.0×10 −2 wt% for Cu and 1.6×10 −3–8.0×10 −3 wt% for Eu) and of host modification (single crystal, polycrystalline and glassy) has been investigated.