Effect Of Mg Doping Research Articles

CBD-synthesized Mg-doped CdS thin films for hybrid solar cells and self-powered photodetectors

Mg-doped CdS samples were deposited via chemical bath deposition onto fluorine-doped tin oxide slides with varying levels of Mg-doping. Structural analysis revealed improved crystal quality in CdS films upon Mg incorporation. Morphological examinations indicated a reduction in grain size alongside appearance of smooth, void-free surfaces particularly evident at 3 % Mg-doping. Mg-doping also resulted in enhanced transparency of CdS films, notably at 3 % and 5 % within the visible spectrum. Efficient exciton dissociation was observed in hybrid solar cells based on 1 % and 3 % Mg-doped CdS, as evidenced by photoluminescence. Top-performing solar cell achieved an efficiency of 0.220 %, nearly seven times that of control device. 5 % Mg-doped CdS-based photodetectors exhibited favorable photosensing characteristics: a responsivity of 0.011 A/W, detectivity of 4.4 × 108 Jones, external quantum efficiency of 3.1 %, and rise/decay times of 26/25 ms at zero bias. These findings underscore beneficial effects of Mg-doping on both hybrid solar cell and self-driven photodetector performance.

Effect of Mg-doping on electrochemical performance of PrBaFe2O5+δ cathode materials for solid oxide fuel cells

PrBaFe2O5+δ (PBF) is one of the promising cathode materials for intermediate-temperature solid oxide fuel cell (IT-SOFC) technology. However, as the operating temperature decreases, the electrochemical performance of this material deteriorates rapidly. To counter this, various doping strategies have been tested and reported in order to improve the electrochemical properties of this material at intermediate-temperatures. In this study, Mg-doping to partially substitute Fe of PBF was investigated. PrBaFe2–xMgxO5+δ (PBFMgx, x=0.1, 0.15, 0.2, 0.3) materials were successfully synthesized, and their electrochemical performance as IT-SOFC cathode was evaluated. It is shown that Mg-doping enhances the conductivity of PBF between 650–800 °C, impacts little on the area-specific resistance of oxygen reduction reaction at and above 700 °C, and, most significantly, improves the power density of the Ni-SDC/SDC/PBFMg0.15 single cell by 52% compared to the un-doped PBF. This enhanced electrochemical performance is attributed to the improvement in PBF conductivity by Mg-doping.

Research on the effect of mg doping on the properties of ZnO nanorods

Research on the effect of mg doping on the properties of ZnO nanorods

Enhanced photoluminescence characteristics in Mg doped Alq3: An insight into doping mechanism

The present paper deals with the investigations on the effect of Mg doping on the structural and photophysical properties of Alq3 thin films. Mg doped Alq3 powders, with varying Mg concentrations, are synthesized using co-precipitation method and their thin films are deposited using vacuum evaporation method. These films are subjected to different analytical analyses to study the effect of Mg doping on the structural and photophysical properties of Alq3. It has been observed that Mg is attached at the central part of the Alq3 molecules making bonds with Al, N and O atoms. In this process, Mg atoms transfer electrons to Alq3 molecules and increases the electron density in its highest occupied molecular orbital (HOMO). Increased HOMO electron density in Mg doped Alq3 results in the improvement in its photoluminescence characteristics. Highest photoluminescent characteristics are observed for Mg doped Alq3 having 1.5 % (by mole) Mg which shows almost 2-fold enhancement in photoluminescence quantum efficiency (PLQY) and 3-fold enhancement in radiative decay rate. The results obtained in this work suggest that Mg doped Alq3 films may be integrated in high performing organic light emitting devices.

Highly nanocrystalline Mg doped ZnFe2O4 powders for rapid and simultaneous adsorption of Lead, Copper, and Cadmium heavy metals ions in synthetic / sea waters

This research aims to investigate the effect of Mg doping on individual and simultaneous adsorption of Pb+2, Cu+2, and Cd+2 heavy metals in aqueous solution and in seawater samples, by Zinc ferrite nanoparticles. The Mg-doped Zinc ferrite nanoparticles are synthesized successfully by the sol-gel route and varying Mg concentrations. TEM, XRD, FTIR, Raman, and XPS characterizations confirm the cubic spinel structure of Zinc ferrite with a semi-spherical shaped nanosized particles (10-15nm) irrespective of Mg doping content. The BET surface area manifests a significant increase within Mg doping (39.3 m2/g) compared with the pure zinc ferrite (28.4 m2/g). Accordingly, Mg-doped Zinc ferrite powders demonstrate considerable adsorption capacities for Pb+2 (143.5mg/g), Cu+2 (117mg/g), and Cd+2 (77mg/g) within 2h under optimized experimental conditions. The prepared nanopowders exhibit high selectivity towards Pb+2 in simultaneous adsorption in aqueous solutions (85mg/g) and real seawater samples. Nonetheless, the selectivity of Pb+2 ions drops dramatically to 25mg/g within real seawater samples due to the strong ionic strength of high-salinity seawater. This study provides insights into the importance of doped spinel ferrite nanoparticles in highly efficient, rapid, and simultaneous adsorption of heavy metals. Besides, it reveals the challenge of performing the adsorption process in real seawater.

Understanding the electrochemical properties of Mg-doped Li2MnO3: first-principles calculations.

Non-transition metal doping, especially for Mg, has been gradually employed to optimize the electrochemical performance of Li-rich cathode material Li2MnO3. However, the effects of Mg doping on the electrochemical behavior of Li2MnO3 have not been studied extensively. In this work, we investigate the effect of Mg doping at both the 2b (in the Li/Mn mixed layer) and 4h (in the Li layer) Li sites on the electrochemical properties of Li2MnO3 through first-principles calculations and ab initio molecular dynamics simulations. The local lattice structure, electronic density of states, Bader charge, delithiation voltage, lattice oxygen stability and Li diffusion kinetics are examined. Electronic structure analysis shows that Mg can activate the electrochemical activity of surrounding Mn by charge transfer, making Mn participate in charge compensation at the initial delithiation stage. Mg doping can also cause an increase in the average oxygen vacancy formation energy and hence depress the oxygen release during the delithiation process. Molecular dynamics simulations show that the diffusion kinetics of Li ions in Mg2b-Li2MnO3 is enhanced with respect to the undoped one, whereas Mg doped at the 4h site cannot improve the diffusion kinetics of Li ions. Further studies found that Mg doped at the 2b site results in a decrease in the energy barrier for the intra-layer diffusion and an increase in the energy barrier for the inter-layer diffusion of the nearby Li vacancies.

Effects of Mg Doping to a LiCoO2 Channel on the Synaptic Plasticity of Li Ion-Gated Transistors.

Artificial synapses with ideal functionalities are essential in hardware neural networks to allow for energy-efficient analog computing. However, the realization of linear and symmetric weight updates in real synaptic devices has proven challenging and ultimately limits the online training capabilities of neural network systems. Herein, we investigate the effect of Mg doping on a LiCoO2 (LCO) channel in a Li ion-gated synaptic transistor, so as to improve long-term and short-term plasticity. Two transistor structures, based on a lithium phosphorus oxynitride electrolyte, were examined by using undoped LCO and Mg-doped LCO as the channel material between the source and drain electrodes. It was found that Mg doping increased the initial channel conductance by 3 orders of magnitude, which is probably due to the substitution of Co3+ by Mg2+ and the compensation of hole creation. It was further found that the doped channel transistor showed good retention characteristics and better linearity of long-term potentiation and depression when voltage pulses were applied to the gate electrode. The improved retention and linearity are attributed to an extended range of the insulator-to-conductor transition by Mg doping and Li-ion extraction/insertion cooperated in the LCO channel. Using the obtained synaptic weight update, artificial neural network simulations demonstrated that the doped channel transistor shows an image recognition accuracy of ∼80% for handwritten digits, which is higher than ∼65% exhibited by the undoped channel transistor. Mg doping also improved short-term plasticity such as paired-pulse facilitation/depression and Hebbian spike timing-dependent plasticity. These results indicate that elemental doping to the channel of Li ion-gated synaptic transistors could be a useful procedure for realizing robust neuromorphic systems based on analog computing.

Synergistic effects of Mg doping on TiO2 for improved toxic gas sensing performance at room temperature

The gas sensing characteristics of magnesium (Mg)-doped titanium dioxide (TiO2) films were investigated using a spray pyrolysis method. TiO2 Thin films with varying Mg doping concentrations (0, 2.5, and 5 weight percentages) were deposited and tested for their gas detection ability to organic compounds such as ethanol, butanol, toluene, xylene, and formaldehyde at room temperature. Results disclosed that introducing Mg into TiO2 enhanced the gas sensing characteristics, particularly for formaldehyde. Mg-doped TiO2 film improved the change in electrical resistance during gas adsorption, leading to an increased response in formaldehyde detection. Additionally, XRD revealed the crystal structure, while Raman spectroscopy provided insights into molecular vibrational modes of the fabricated films. FESEM allowed for high-resolution imaging of surface morphology, and atomic force microscope assessed surface roughness and other properties of the as deposited samples. UV-Vis spectroscopy was utilized to examine the optical characteristics. The collective results strongly indicated that the introduction of Mg significantly improved the gas-sensing capabilities of TiO2 films, making them highly promising for various gas-sensing applications.

Nanostructured Mg-doped Mn–Cr spinel oxide cathodes for solid oxide fuel cells with optimized performance

The cathode properties are critical for solid oxide fuel cells (SOFCs) performance and a major challenge for commercialization. This study employs the impregnation method to produce uniformly distributed Mg-doped manganese-chromium spinel oxide nanoparticles infiltrated into a network on the Gd0.1Ce0.9O1.95 (GDC) skeleton as SOFC cathodes. The effects of Mg doping on the performance of these nanostructured spinel oxides are investigated. Both experimental results and density functional theory (DFT) calculations demonstrate that Mg doping can optimize the electronic structure of the manganese-chromium spinel oxide, increase the oxygen vacancy concentration, and significantly enhance the electrical conductivity and oxygen reduction reaction (ORR) catalytic activity. The Mg-doped manganese-chromium spinel oxide cathode exhibits superior performance, with an area-specific polarization resistance of 0.33 Ω cm2 and a maximum power density of 976 mW cm−2 at 800 °C. Moreover, the nanostructures of the cathode barely change after 100 h of cell operation. These findings provide a new strategy for optimizing the performance of SOFC spinel oxide cathodes.

Ground state structural, electronic and magnetic properties of Mg-doped LaMnO[formula omitted] perovskite: GGA+U study

The effect of Mg doping on the ground state structural, electronic and magnetic properties has been investigated by means of GGA+U calculations. The inspection of the structure, magnetic moment data and density plots, show that by substituting La by Mg at the La site at a concentration of 0.25, the compound exhibits a Pbnm orthorhombic structure and a half metallic ferromagnetic behaviour with degenerated Mn-eg states. The corresponding average A-site cation radius 〈rA〉 value does not allow metallic-insulator phase transition in the compound. However, by doping Mg on Mn site with the same proportion, the resulting compound shows a Pbnm orthorhombic structure and a half metallic behaviour with degeneracy lifting in Mn-eg states. Our results obtained for LaMn0.75Mg0.25MnO3 agree more with experimental data than those obtained for La0.75Mg0.25MnO3, suggesting that Mg will prefer to substitute at the Mn site due to their close ionic radii.

Effect of Mg doping on carrier recombination in GaN

Time-resolved photoluminescence measurements have been performed on Mg-doped GaN for Mg concentrations in the low- to mid-1019 cm−3. As-grown and annealed (600–675 °C) samples were studied. In the as-grown samples, the nonradiative carrier lifetime was found to be about 200 ps and nearly independent of the Mg concentration. Upon annealing, the carrier lifetimes shorten to ∼150 ps but, again, show little dependence on the annealing temperature. The analysis of possible Shockley–Read–Hall recombination centers and their behavior during doping and annealing suggests that the main nonradiative recombination center is the Mg–nitrogen vacancy complex. The weak dependence of the PL decay times on temperature indicates that carrier capture into this center has a very low potential barrier, and the nonradiative recombination dominates even at low temperatures.

Tuning lattice defects and photocurrent response of ZnO thin films by Mg doping and Ar-H2 atmospheric plasma treatment

The effects of Mg doping and Ar-H2 atmospheric pressure plasma jet (APPJ) treatment on zinc oxide (ZnO) thin films were investigated. Mg doping has been demonstrated to facilitate the incorporation of atomic hydrogen in the ZnO lattice via Ar-H2 APPJ. The co-doping of Mg and H changed ZnO’s primary oxygen defect type from vacancy (VO) to interstitial (Oi), which reduced photocorrosion significantly. The dominance of interstitial defects (i.e., Zni and Oi) in the H-doped Zn0.9Mg0.1O thin film was confirmed by photoluminescence spectroscopy. Zni shallow donors improved light absorption at wavelengths > 650 nm, increasing the film’s photocurrent density. Without Mg, doping H via Ar-H2 APPJ was ineffective for pure ZnO thin film. The dominance of VO in pure ZnO thin film after APPJ, though enhanced light absorbance, gave rise to an erratic photocurrent response due to the instability of VO. The lack of acceptor states also led to severe photocorrosion.

Effect of Mg doping on dielectric properties of ZnO nanoparticles synthesized by microwave-assisted combustion route

The primary aim of this research work is to study the dielectric properties of nanoscale ZnO and Mg-doped ZnO nanoparticles (NPs). The microwave-assisted combustion technique was used to synthesize ZnO and Mg-doped ZnO NPs (2, 4, and 6 atomic % of Mg). XRD (X-ray diffraction), FTIR (Fourier transform infrared) and SEM (Scanning electron microscope) methods were used to characterize the materials. From the XRD pattern, the phase confirmation and crystallite size of ZnO and Mg-doped ZnO NPs were estimated. The study of dielectric properties such as dielectric loss and permittivity, impedance and AC conductivity were observed in the range of frequency (1–106 Hz). The permittivity of ZnO and 6% Mg-doped ZnO showed an enhanced dielectric property than other doped materials at higher frequency. The additional mobile carriers added to the material as a result of raising the percentage of doping resulted in an increase in the material's dielectric loss. The hopping and tunnelling mechanism, which may be attributed to the migration of electrons into the conductive network formed by the crystallites of 6% Mg-doped ZnO and ZnO NPs, caused progressively increase in the values of AC conductivity of doped nanoparticles as the frequency range was increased. The impedance (real and imaginary) was decreased with increase in the amount of Mg (in terms of atomic %).

Crystalline phase purity and twinning of Mg-doped zincblende GaN thin films

Zincblende (zb) GaN thin films doped with Mg were grown by molecular beam epitaxy on GaAs under Ga- and N-rich conditions and different Mg cell temperatures. X-ray diffraction and electron-backscatter diffraction determined the ideal orientation of the zb-GaN, its textural relationship to the substrate, wurtzite and twin content, and their interfaces with the GaN matrix. A comparison to pole figure simulations allowed a thorough description of orientation of wurtzite inclusions and twins, forming interfaces along the 〈111〉 directions of the matrix. The results revealed zincblende volumetric purities as high as 99.9 % and twinning as low as 1.3 %. Ga-rich conditions and lower doping cell temperatures led to the highest phase purities. Moreover, crystalline and surface quality are also deeply linked to the wurtzite inclusions and twinning obtained. Films with the least amounts of these displayed the highest quality. This is likely due to excess Ga atoms on the surface helping the Mg doping atoms incorporate more orderly into the growing film. The results from this investigation provide a deeper understanding of the effects of Mg doping on the crystalline structure of zb-GaN films, paving the way for practical applications of zincblende nitrides in modern optoelectronic devices.

Structural and physical properties of Mg-doped CuCoO2 delafossite thin films

In this work, Mg-doped CuCoO2 (CCO) delafossite oxide was synthesized by a low-cost technique, namely spray pyrolysis. We investigated the effects of Mg doping on the structure, morphology, chemical composition, and optical properties of CCO with different percentages (1%, 2%, 3%, 4%, 5%). Using X-ray diffraction analysis, we observed an excellent agreement without any impurities in the Mg-doped CuCoO2 delafossite structure. To analyze the variations caused by doping on the quality, we examined the morphology of the produced films using field emission scanning electron microscopy. The deposited samples exhibited different textures and surfaces that were evenly distributed throughout the substrate. Furthermore, we utilized a transmission electron microscope to examine the Mg-doped CuCoO2 films. The CuCo1-xMgxO2 with x = 0.01 delafossite displayed excellent crystallinity. The results indicated that the fringe distances of 0.23 nm, 0.85 nm, and 0.16 nm corresponded to the spacings of the CuCoO2 lattice planes (110), (222), and (332) respectively. Optical properties were measured using UV–Vis spectroscopy at room temperature, revealing weak visible light absorption. It was found that CuCo1−xMgxO2 could be transparent to photons with energies in the visible range. Additionally, the band gap decreased in parallel with increasing Mg doping until a percentage of 3% (0.03), where a value of Eg = 1.75 eV was obtained.

Impact of Mg-doping on the structural, optical, and magnetic properties of CuO nanoparticles and their antibiofilm activity

Doping in metal oxide systems is being chased by many researchers since it is enhancing their properties. In the present study, Cu1-xMgxO nanoparticles, capped with EDTA were synthesized by the chemical co-precipitation method, with x = 0.000, 0.005, 0.010, 0.015, and 0.020, and further characterized by different techniques. The impact of doping by Mg2+ ions on the structural, optical, and magnetic properties of CuO nanoparticles was investigated and the antibacterial activity of the synthesized nanoparticles was studied by antibiofilm screening. The x-ray Powder Diffraction (XRD) patterns show the formation of a pure CuO phase with a good incorporation of Mg-dopant into the CuO lattice due to the comparable ionic radii of Cu2+ and Mg2+ ions. The Mg-dopant increases the crystallite size from 25 nm (at x = 0.000) to 28.12 nm (at x = 0.020). The Transmission Electron Microscope (TEM) images reveal the effect of Mg-doping on the morphology of CuO nanoparticles by decreasing their agglomeration, resulting in more uniform spherical-shaped nanoparticles. Energy Dispersive x-ray (EDX) and x-ray Photoelectron Spectroscopy (XPS) confirm the purity and the successful development of Mg-doped CuO nanoparticles. The changes in the characteristic vibrational modes of CuO are studied by Raman spectra, upon Mg-doping. Furthermore, the optical properties explored by Ultraviolet-Visible (UV–vis) spectroscopy reveal a redshift of the absorption peaks of CuO nanoparticles due to the Mg-doping. The energy gap (Eg) is affected by Mg-doping, where its broadening is attributed to the quantum confinement effect in CuO. The magnetic properties were investigated by Vibrating Sample Magnetometer (VSM) at room temperature. Cu1-xMgxO nanoparticles have combined paramagnetic and weak ferromagnetic behaviors. Besides, Cu1-xMgxO nanoparticles exhibited significant antibiofilm effects. These results highlight the potential use of Mg-doped CuO nanoparticles as antibiofilm agents.

Effect of Mg Doping on the Structural, Optical and NO<sub>2</sub>-sensing Properties of ZnO Thin Films Prepared by Modified SILAR Method

In this report, we have prepared undoped and Mg-doped ZnO thin films by a modified successive ionic layer adsorption and reaction (SILAR) method. The structural, surface morphological, chemical compositional, and optical properties of pure and Mg-doped ZnO thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible (UV-VIS) spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. The XRD patterns of undoped and doped films have wurtzite crystal structures with preferential orientation along the (101) plane, without any secondary phases. Addition of Mg into host ZnO influenced surface morphology of the film. Predominant nanorods-like surface morphology of undoped ZnO turned to be predominant nanoflowers-like surface morphology after addition of Mg. UV-VIS spectra showed that the energy band gap of films increased with increase Mg doping concentration. EDS and FT-IR spectroscopy confirmed the successful Mg doping. Gas sensing properties of the undoped and Mg-doped ZnO thin films were tested based on the electrical resistance changes upon exposure to different concentrations of a NO2 gas at 200°C operating temperature. Mg-doped ZnO (3 wt%) showed higher response compared to other wt% and exhibited the highest responses of 2.95, 9.51, and 9.93 when exposed to 25, 50, and 100 ppm concentrations of the NO2 gas at 200°C, respectively. The response/recovery time of the Mg-doped ZnO thin film were 6/75, 14/88, and 14/89 s at 25, 50, and 100 ppm, respectively.

The Effect of Mg Content on the Physical Properties of ZnO Films Deposited by Ultrasonic Spray Pyrolysis

ZnO is a versatile material and tailoring its physical properties to the field of application is technologically crucial. Intentionally doping with a foreign element is the most common and useful method for that. In this presented work, ZnO films doped at different Mg concentrations (0%, 5%, 10%, and 15%) were deposited onto glass substrates by ultrasonic spray pyrolysis in order to investigate the effect of Mg doping. AFM and SEM images captured for the morphological investigations revealed that Mg doping deteriorated the surface of the films. The structural analysis showed that the Mg doping at 5% enhanced the structural properties, but the crystallization level was adversely affected at higher Mg concentrations. Optical band gap and Urbach energies increased from 3.30 eV to 3.45 eV and from 79.5 meV to 119.8 meV, respectively. The lowest electrical resistivity was noted as 8.72101 cm for Mg-doped ZnO films at 5%.

First principles study of the effect of (Mg, C) doping and Zn vacancies on the carrier activity, lifetime, visible light effect, and oxidation–reduction reaction of ZnO(0 0 1) monolayers

At present, some progress has been made in the study of Mg doping on the photocatalytic performance of ZnO monolayers. However, few studies on the effects of C impurities, Mg doping, and Zn vacancy coexistence on the electronic structure and photocatalytic performance of ZnO monolayers have been conducted. The preparation of ZnO through metal organic chemical vapor deposition growth technology inevitably generates C impurities, which are difficult to remove. To solve such problems, we investigated the effects of Mg doping and the coexistence of C impurities and Zn vacancies on the electronic structure and the photocatalysis of ZnO monolayers with a generalized gradient approximation plane-wave ultrasoft pseudopotential method based on the framework of density-generalized functional theory. Results showed that all doped systems had negative formation energy under O-rich conditions, indicating that the systems easily formed. The cohesion energy of Zn33CiCZnMgO36(Ci1−/2+/3+/4+,CZn2+) monolayers was relatively large, and the systems were stable. The absorption spectra of the doped systems red-shifted in a wavelength range of 425–800 nm compared with the absorption spectrum of the undoped Zn36O36 monolayer system. All doped systems were able to react with water to produce H2 and O2 at pH of 0 or 7. The Zn34CiCOMgO35 (Ci1−,CO2−) monolayer exhibited the strongest activity, the best absorption spectrum red shift, the smallest work function, the longest carrier lifetime, and the best HER ability. The Zn34CiCOMgO35 (Ci1−,CO2−) monolayer was considered a strong candidate for photocatalytic hydrogen production. Overall, this study has a theoretical reference value for the design and preparation of novel photocatalytic functional materials.

Effect of Mg-doping on the hydration reactivity of polycrystalline dicalcium silicate: A study explored by DFT simulation

Dicalcium silicate is widely used in belite-rich cement due to its lower Ca/Si ratio, energy consumption and CO2 emissions than tricalcium silicate, and its hydration reactivity plays an important role in the strength development of the cement. This work provides an atomic-scale understanding of the electronic structure on the hydration reactivity of C2S polycrystals and elucidates the effect of Mg-doping on their reactivity and intrinsic mechanisms. The results show that the hydration reactivity is more closely related to electrophilic attack due to the absolute numerical dominance of electrophilic active sites and the presence of steric hindrance. The hydration reactivity of α′L-C2S is mainly achieved by electrophilic attack, γ-C2S mainly by nucleophilic attack, and β-C2S by both electrophilic and nucleophilic attack. Among these three polymorphs, the order of hydration reactivity is β-C2S > α′L-C2S > γ-C2S. Mg-doping can change the crystal and electronic structure used to characterize the chemical reactivity of C2S, and the higher the hydration reactivity of intrinsic minerals, the greater the effect of Mg doping. Mg-doping causes irregular distortions in the overall structure and local coordination of α′L- and β- C2S, which coincide with the structural activation caused by impurities. The hydration hysteresis of Mg-doped α′L- and β- C2S is caused by the sharp decrease in the number of reaction sites and a more localization of the effective charge density. In contrast, the LDOS in Mg-doped γ-C2S shows slight change in both aspects, resulting small effect on its hydration activity. These insights should pave an effective way to regulate the hydration reactivity of cementitious materials by selecting suitable foreign ions.