Effect Of Aluminum Doping Research Articles

Effect of doping and preparation parameter on AC conductivity and dielectric modulus formalism of Al doped DLC thin films

Here, we report the composite effect of aluminum doping on the dielectric response of Diamond-Like Carbon (DLC) thin films. In addition, the contribution from preparation parameters like acetylene flow rate is also considered to understand sample behavior. AC conductivity study shows the existence of a nonlinear increase of conductivity with frequency leading toward the Jump Relaxation Model (JRM). The transition frequency (ft) is observed, which increases with conductivity. The study reveals that dielectric response is influenced by space charge conductivity, prompting us to adopt the modified Debye law. Deviation from ideal Debye behavior is also confirmed in dielectric modulus analysis. The deviation is frequency-dependent, and a higher deviation is observed in the high-frequency region. Plotting of the Master curve shows the presence of different relaxation dynamics in different samples. A current-voltage (I-V) study of different samples is also undertaken, showing higher values (greater than unity) of the ideality factor.

Phase Engineering via Aluminum Doping Enhances the Electrochemical Stability of Lithium-Rich Cobalt-Free Layered Oxides for Lithium-Ion Batteries.

Lithium-rich, cobalt-free oxides are promising potential positive electrode materials for lithium-ion batteries because of their high energy density, lower cost, and reduced environmental and ethical concerns. However, their commercial breakthrough is hindered because of their subpar electrochemical stability. This work studies the effect of aluminum doping on Li1.26Ni0.15Mn0.61O2 as a lithium-rich, cobalt-free layered oxide. Al doping suppresses voltage fade and improves the capacity retention from 46% for Li1.26Ni0.15Mn0.61O2 to 67% for Li1.26Ni0.15Mn0.56Al0.05O2 after 250 cycles at 0.2C. The undoped material has a monoclinic Li2MnO3-type structure with spinel on the particle edges. In contrast, Al-doped materials (Li1.26Ni0.15Mn0.61-xAlxO2) consist of a more stable rhombohedral phase at the particle edges, with a monoclinic phase core. For this core-shell structure, the formation of Mn3+ is suppressed along with the material's decomposition to a disordered spinel, and the amount of the rhombohedral phase content increases during galvanostatic cycling. Whereas previous studies generally provided qualitative insight into the degradation mechanisms during electrochemical cycling, this work provides quantitative information on the stabilizing effect of the rhombohedral shell in the doped sample. As such, this study provides fundamental insight into the mechanisms through which Al doping increases the electrochemical stability of lithium-rich cobalt-free layered oxides.

Promotional effect of aluminum doping on the sulfated Fe2O3 catalyst in selective catalytic reduction of NO with NH3

Promotional effect of aluminum doping on the sulfated Fe2O3 catalyst in selective catalytic reduction of NO with NH3

Synergistic effects of aluminum doping and amino functionalization to enhance adsorption capacity of ultrathin-nanosheet-assembled calcium silicate hydrate architectures for effective removal of Pb2+ and Cu2+ from aqueous solution

This study demonstrates for the first time the potential of the novel combination of aluminum (Al) doping and amino functionalization to drastically enhance the adsorption capacity of nanosheet-assembled hierarchical calcium silicate hydrate (CSH) architectures for heavy metal Pb2+ and Cu2+ ions in aqueous solution. The designed and prepared amino-functionalized Al-doped CSH (CASH-NH2) exhibits excellent adsorption capability to adsorb Pb2+ and Cu2+ ions. The maximum adsorption capacity of Pb2+ and Cu2+ ions is 911 and 509 mg g−1, respectively, which is much higher than that of pure CSH and other relative CSH-based adsorbents. The experimental measurements of cation exchange capacity (CEC) and surface composition discover that the adsorption of Pb2+ and Cu2+ ions on CASH-NH2 is preponderantly achieved by the cation exchange and surface complexation, in which Al doping substantially enhances the exchange capacity between Ca2+ of CSH and Pb2+ or Cu2+, and the functional amino groups chelate Pb2+ or Cu2+ to realize surface complexation of CASH architectures. Thereby the excellent adsorption performance of CASH-NH2 is attributed to the significant enhancement in the CEC between Ca2+ of CASH and Pb2+ or Cu2+, and the amino functionalization-induced surface complexation of the CASH, which are achieved by the synergistic effect of Al doping and amino functionalization. This work opens a new way for simultaneously exploiting metal doping and amino functionalization to boost the adsorption performance of other adsorbents to achieve highly efficient removal of toxic cationic species from polluted water.

Crystal Structure of Bismuth-Containing Samarium Iron–Aluminium Borates Sm1−xBixFe3−yAly(BO3)4 (x = 0.05–0.07, y = 0–0.28) in the Temperature Range of 25–500 K

Structural features of new mixed bismuth-containing samarium iron–aluminium borate single crystals Sm1−xBixFe3−yAly(BO3)4 (x = 0.05–0.07, y = 0–0.28) were studied using X-ray diffraction analysis based on aluminium content and temperature in the range 25–500 K. The crystals were grown using the solution-in-melt technique with Bi2Mo3O12 in a flux. The composition of the single crystals was analyzed using energy-dispersive X-ray fluorescence and energy-dispersive X-ray elemental analysis. Temperature dependencies of Sm1−xBixFe3−yAly(BO3)4 unit-cell parameters were studied. Negative thermal expansion was identified below 100 K and represented by characteristic surfaces of the thermal expansion tensor. (Sm,Bi)–O, (Sm,Bi)–(Fe,Al), (Fe,Al)–(Fe,Al), and (Fe,Al)–O interatomic distances decreased with the addition of aluminium atoms. An increase in the (Fe,Al)–(Fe,Al) intrachain bond length at low temperatures in the magnetically ordered state weakened this bond, whereas a decrease in the (Fe,Al)–(Fe,Al) interchain distance strengthened super-exchange paths between different chains. It was found that the addition of aluminium atoms influenced interatomic distances in Sm1−xBixFe3−yAly(BO3)4 much more than lowering the temperature from 293 K to 25 K. The effect of aluminium doping on magnetoelectric properties and structural symmetry of rare-earth iron borates is also discussed.

Study on the different effects of aluminum doping on Fe-Mn and Ni-Mn based compounds as cathode material for sodium-ion batteries

Al-doped Fe-Mn and Ni-Mn based materials with P2-type layered structure has been synthesized and tested as a positive electrode material for rechargeable sodium batteries. The modification mechanisms of Al doping in Fe-Mn and Ni-Mn based materials have been discussed. The synthesized Al-doped Ni-Mn based material Na0.67Mn0.8Ni0.16Al0.04O2 delivers a reversible capacity of 135.1 mAh g−1, which corresponds to 92.1% of the initial capacity with excellent cyclability for 200 cycles. What’s more, it can still remain a capacity of 96.2 mAh g−1 at a current density of 2000 mA g−1. When the voltage range increase to 1.5 – 4.3 V, its initial discharge capacity can reach 190.3 mAh g−1.

Dielectric properties and conduction mechanism of La0.7Sr0.25Na0.05Mn0.95Al0.05O3 perovskite manganite

The present paper reports on the effects of Aluminum-doping on the micro-structural and dielectric properties of La0.7Sr0.25Na0.05Mn0.95Al0.05O3 ceramics. The analyses of the X-ray diffraction data by the Rietveld refinement technique confirmed the formation of a rhombohedral phase in the R 3 ¯ c space group. The dielectric properties were analyzed by the complex impedance spectroscopic techniques in a wide temperature extent and a spectral range between 2 kHz and 1 MHz. The Nyquist diagram with a single semicircular arc is explained by the contribution of two conducting phases associated with the effects of grains and grain boundaries. The conductivity spectrum obeyed Jonscher’s power law and the conduction mechanism was attributed to the correlated barrier hopping mechanism. The dielectric parameters such as the dielectric constant (ε″) showed a compositional dependence, indicating the prevalence of inter-grain conductive contribution and microstructural features which can be interpreted by the Maxwell–Wagner process.

Effect of aluminum doping on the structural, optical and electrical properties of ZnO thin films processed under thermal shock conditions

The structural, morphological, optical, and electrical properties of Al-doped ZnO thin films annealed under thermal shock conditions were studied. The films were prepared using the sol–gel method and deposited on glass substrates by dip-coating technique. The effects of varying the concentration of aluminum (Al) were analyzed using X-ray Diffraction (XRD), scanning electron microscope (SEM), UV–Vis, and the 4-point probe method. The XRD data demonstrated a degradation in the crystalline structure of the films and the emergence of other preferred directions (100) and (101), which supported the creation of a hexagonal wurtzite structure. The SEM images supported the findings of the XRD analysis. The best electrical and optical performance was obtained for an Al concentration of 1 at%, where the resistivity value was 0.191 Ω.cm and the band gap was 3.26 eV, with a high transmittance greater than 90%.The findings of this study render the developed thin-film architecture a viable candidate for high-performance optoelectronic applications.

Preparation of aluminium doped Ta3N5 films via nitridation of sputtered tantalum oxide films

A multi-step synthetic method is presented for the synthesis of novel aluminium doped Ta3N5 films. Two mechanisms for the incorporation of aluminium into Ta3N5 are proposed and the effect of aluminium doping on the as-deposited tantalum oxides and annealed Ta3N5 films is investigated with XRD, EDS, SEM and SIMS analysis. These results are contrasted with previous work detailing the incorporation of Cr into Ta3N5 and it is observed that aluminium does not reach a solubility limit in Ta3N5 under the conditions explored. The preferred processing regimes for synthesizing Al–Ta3N5 films as p-type Ta3N5 photo-electrode candidates are outlined.

Atomistic Insights into Aluminum Doping Effect on Surface Roughness of Deposited Ultra-Thin Silver Films.

Ultra-thin and continuous metallic silver films are attracting growing interest due to the applications in flexible transparent conducting electrodes. The surface morphology and structure of silver film are very important for its electrical resistivity and optical loss. Therefore, roughness control is essential for the production of ultra-thin metallic electrode film. We have investigated the effect of aluminum doping on the improvement of surface morphology of ultra-thin silver films using molecular dynamics simulations. Al-doped silver films showed smaller surface roughness than pure silver films at various substrate temperatures. When the temperature of the substrate was 600 K, the roughness of Al-doped silver film first decreased, and then increased with the increase of the incident velocity of silver atoms. Silver atoms were more likely to agglomerate on the surface of the substrate after adding aluminum atoms, as aluminum dopants promoted the immobilization of silver atoms on SiO2 substrate due to the anchoring effect. The smoother surface could be attributable to the reduced mean free path of silver due to the cage effect by the aluminum dopant.

Thermoelectric, Electronic, and Optical Response of Nanostructured Al‐doped ZnO @ 2D‐TiC Composite

AbstractZnO is one of the sought‐out materials for thermoelectricity. This study investigates the effect of aluminum doping, and titanium carbide (TiC) modification on the thermoelectric properties of ZnO through the synthesis of undoped ZnO, Al‐doped ZnO (Al‐ZnO), and TiC modified Al‐doped ZnO (TiC@Al‐ZnO) nanocomposite by the hydrothermal method and mechanical alloying. XRD, TEM, and SEM were used for structural and morphological studies. The electrical and thermal conductivity measurements on the nanocomposite were obtain using Van der pauw 4 probe collinear method. A decrease in thermal conductivity of ZnO from 7.62 to 5.75 W/cm K is observed after been modified with Al and TiC. TiC@Al‐ZnO nanocomposite exhibits the lowest thermal conductivity and highest power factor than Al‐doped ZnO. Furthermore, the impact of TiC and Al revealed an enormous effect on the Seebeck coefficient of ZnO reaching 105 μV K−1 AT 960 K, and a figure of merit value of 0.28 at 960 K. The increase in negative Seebeck coefficients suggests that the amount of active charge carrier, with significant energy, was temperature and structure depend. The experimental data obtained in this work showed the effect of both Al concentration and TiC nanosheet reinforcement on the thermoelectric properties of ZnO.

An in-depth understanding of the effect of aluminum doping in high-nickel cathodes for lithium-ion batteries

High-nickel layered oxides, LiNixM1-xO2 (x ≥ 0.6), are regarded as highly promising materials for high-energy-density Li-ion batteries, yet they suffer from short cycle life and thermal instability. Tuning these cathodes for improved performance via elemental doping is an effective approach, and Al has proven to be the most popular and commercially successful of all the dopants. Despite the popularity of Al doping, the practical effects of varying Al content on high-nickel cathodes are still unknown. Herein, a series of high-Ni cathodes, LiNi0.85Co0.15-xAlxO2 (NCA, x = 0, 0.023, 0.056, 0.096, and 0.15), are synthesized and investigated. It is found that the cycling, air stability, lattice structure, and interphase stability of NCA are gradually improved with increasing Al content from 0 to 5.6%. Further increase in Al content beyond 5.6% triggers adverse effects, including significantly increased residual lithium on the cathode surface and compromised initial capacity resulting from the formation of impurity phases (LiAlO2 and Li5AlO4). A 5.6% Al doping is suggested to be optimal, which suppresses the secondary-particle pulverization and reduces residual lithium species as well as enhances the electrode/electrolyte interphases, thereby improving both rate capability and cycling performance at ambient and high temperatures. Overall, this study delivers fundamental insights into Al doping and provides guidance for the optimal use of Al dopants in developing advanced cathodes.

Chemical bath deposition of aluminum doped zinc sulfide thin films using non-toxic complexing agent: Effect of aluminum doping on optical and electrical properties

Zinc sulfide (ZnS) and aluminum doped zinc sulfide (ZnS:Al) thin films have been prepared by chemical bath deposition onto glass substrates at 85 °C using non-toxic complexing agents by varying the Al concentration between 0 wt. % and 18 wt. %. The ZnS and ZnS:Al thin films exhibited a hexagonal wurtzite crystal structure and showed (008) preferential orientation. The Field Emission Scanning Electron Microscope (FESEM) images of the film showed that the glass substrate was nicely covered by compact and dense mosaic like nanostructures. The elemental composition of ZnS and ZnS:Al thin films was measured by energy dispersive x-ray spectroscopy. X-ray photoelectron spectroscopy (XPS) demonstrates the doping of Al into ZnS. From the XPS spectra, the binding energy (BE) values were observed to shift toward the lower BE side for increasing aluminum content. Raman spectra were obtained for the undoped and Al doped ZnS films, which exhibit first-order phonon modes at 328.33 cm−1 and 341.66 cm−1 for the A1/E1 longitudinal optical phonons, and the bands at 253.33 cm−1 and 263.33 cm−1 revealed longitudinal optical phonon–plasmon coupled modes. UV–visible spectrophotometric measurement showed that approximately 70%–80% transmission happened in the visible to near infrared region, with a direct allowed bandgap in the range of 3.52 eV–3.76 eV. A maximum transmittance of 80% was observed for 6 wt. % Al doped ZnS thin films, and the absorption edge shifted toward the blue spectrum region. ZnS and ZnS:Al thin films showed n-type electrical conductivity with carrier concentrations varying from 1.55 × 1017/cm3 to 3.13 × 1017/cm3. Resistivity of the ZnS:Al thin films was decreased with the increase in Al concentration.

The Effect of Doping on the Structure of Zinc Oxide Obtained by Atomic Layer Deposition

Zinc oxide (ZnO) is an interesting inexpensive transparent conductive oxide for use as a transport layer in multilayer solar cells. We present the results of a study of the effect of aluminum doping on the structure of 50-65 nm thin films of zinc oxide obtained by atomic layer deposition (ALD) on different substrates (glass, sapphire with a-plane and c-plane orientations). Analysis of thin films by IR spectra and X-ray diffraction showed the effect of doping on the crystallographic texture of films grown by the ALD method by comparing substrates of simple glass, c-plane Al2O3 and a-plane Al2O3. We found that when doping zinc oxide, the orientation of the substrate plays a substantial role, which affects the mechanism of interaction of zinc oxide with a doping agent, leading to changes in the structure and properties of ZnO due to the interaction between ZnO molecules and water to form a Zn-O-H bond. Doping with aluminum leads to a strain stress, resulting in distortion of the structure and a decrease in the concentration of oxygen vacancies. This is turn facilitates the flow of water molecules into the interlayer space and an increase in the density of the positive charge on the metal cation, which leads to an increase in the coordination number, i.e. to an increase in the number of hydroxyl groups.

Effect of Aluminum Doping on the Performance and Microstructure of Methyl-Modified SiO2 Sol

With methyltriethoxysilane as hydrophobic precursors and aluminum isopropoxide as the aluminum source, the Al2O3/SiO2 sols and their gel materials were prepared. The effects of aluminum content (nAl) on the viscosity (η), density (ρ), reaction rate constant (k), Gibbs energies of activation for viscous flow (ΔG*), particle size of Al2O3/SiO2 sols were studied. And the high temperature calcined materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The results show that, with the increase of nAl, the η, n and ΔG* values of the Al2O3/SiO2 sols decrease while the k and ρ values and average particle sizes increase. There is strong intermolecular interaction between the Al2O3 and SiO2 sol molecules. The Al-O-Si bond exists in the Al2O3/SiO2 materials before and after calcination at 350 °C. Calcination at 350 °C in N2 atmosphere can change the phase structure of Al2O3/SiO2 sample greatly, which can make the γ-AlOOH in the Al2O3/SiO2 gel material convert to γ-Al2O3 through dehydration.

Structural, electrical, optical and morphological properties of aluminum-doped TiO2 thin films deposited by spray pyrolysis method

In this research, highly transparent thin films of pure and doped titanium dioxide (TiO2) with various amount of aluminum (0–5 mol%) were prepared by sol–gel method and were coated on a FTO substrate at 500 °C by spray pyrolysis. Thermogravimetry and differential thermal analysis were employed to study the thermal transformation behavior of the xerogel. The effects of aluminum doping on structural, morphological, optical, and electrical properties of TiO2 samples were evaluated using X-ray diffraction (XRD), field emission scanning electron microscopy, atomic force microscopy, UV–Vis absorption spectroscopy, ellipsometry and four point probe techniques. XRD results reveal that all thin films have anatase crystal structure and it can be seen that the preferred growth orientation of the TiO2 thin films depends on the Al doping levels. The results show that by increasing the amount of aluminum dopant (0 to 5 mol%), the grain size, crystalline plane distance and roughness are decreased, as well the resistivity of the TiO2 layers decreases until it reaches to a minimum value at 3 mol% of aluminum. On the other hand, the band gap rises from 3.28 to 3.39 eV. The ellipsometry measurements demonstrate that the refractive index of TiO2 thin films decrease from 1.96 to 1.89 at 632.8 nm and the extinction coefficient increase with Al doping content.

Effect of Aluminum doping on potential barrier of gold-ZnO-Si Schottky barrier diode

In the present work, two different heterojunctions layered Schottky barrier diodes have been fabricated at 100 °C. First is Au/ZnO/p-Si Schottky barrier diode and second is Au/Al-ZnO/p-Si Schottky barrier diode where Aluminum doped ZnO has been used. Thin films of ZnO and Al-ZnO have been first analyzed using AFM, EDX, and XRD. Then potential barrier of the diodes have been evaluated by I-V characteristics to find out effect of Aluminum doping in ZnO on the barrier potential of Schottky diode.

Impact of Al Doping and Surface Coating on the Electrochemical Performances of Li-Rich Mn-Rich Li1.11Ni0.33Mn0.56O2 Positive Electrode Material

Li and Mn-rich positive electrode materials, Li[LixTM1−x]O2 (TM = Ni, Co, and Mn), with a single-phase layered structure have been considered for use in next-generation Li-ion batteries for electric vehicles and many advanced applications. Despite their high specific capacity >250 mAh g−1, the commercialization of these materials is hindered by poor rate capability and voltage decay originating from transition metal migration to the lithium layer. Herein, the effect of aluminum doping and aluminum oxide surface coating on the structural and electrochemical performances of Co-free Li1.11Ni0.33Mn0.56O2 was studied. All synthesized materials were single phase with a similar morphology and amount of Ni in the Li layers. Even though the discharge capacity and capacity retention were slightly improved, there was no significant impact of the addition of Al on the rate of voltage fading during charge-discharge cycling as previously reported.

Dual Effect of Aluminum Doping and Lithium Tungstate Coating on the Surface Improves the Cycling Stability of Lithium-rich Manganese-based Cathode Materials

Dual Effect of Aluminum Doping and Lithium Tungstate Coating on the Surface Improves the Cycling Stability of Lithium-rich Manganese-based Cathode Materials

Aluminium doping in iron oxide nanoporous structures to tailor material properties for photocatalytic applications

In this study, metal doping of iron oxide nanostructures grown by anodization is successfully achieved by the simple cost effective technique of electrochemical doping. Structural and morphological characterizations of all the samples are done using X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy in conjunction with field-emission scanning electron microscopy, respectively. A detailed analysis of the X-ray photoelectron spectra is done for all the samples to obtain the effect of aluminium doping on the multiplet peak positions of Fe 2p and different species of oxygen. Analysis of the valence band X-ray photoelectron spectra (VB XPS) reveals a displacement of ‘valence band edge’ towards higher energy on doping. The VB XPS coupled with optical data is used for evaluating the shift in the Fermi level towards the conduction band minimum, which indicates the formation of donor defect level on doping. The reduction in band gap from 1.96 to 1.72 eV and enhanced electrical conductivity on doping are observed to produce an improvement in the photo catalytic activity for aluminium-doped nanostructures compared to undoped.