Doping Type Research Articles

Effects of amorphous phase and yttrium on flash sintering and microstructures of ZrO2–SiO2 ceramic nanocomposites

AbstractFlash sintering has been used to consolidate a wide range of ceramics and ceramic composites. However, flash sintering of ceramic nanocomposite with a substantial amorphous phase is rarely studied. Meanwhile, the effects of yttrium addition on the flash sintering behaviors and microstructures of ZrO2‐based ceramic nanocomposite remain unknown. Herein, ZrO2‐SiO2 crystalline‐amorphous ceramic nanocomposites (CACNs) with different contents of amorphous phase and two types of yttrium dopants were sintered by flash sintering. Results showed that the content of amorphous phase (SiO2) had significant effects on the flash sintering behavior. The CACN with 65 mol% SiO2 was nonflash sinterable due to the high electric resistivity of SiO2, whereas, the CACN with 45 mol% SiO2 can be flash sintered to high densification within 35 seconds. The flash‐sintered CACNs consisted of ZrO2 nanocrystallites distributed in an amorphous SiO2 matrix. Flash sintering enhanced the tetragonal‐to‐monoclinic phase transformation of ZrO2. In addition, influences of yttrium dopant on CACNs were also investigated. Yttrium dopants can rapidly dissolve in ZrO2 lattices and show a tetragonal phase stabilization effect during flash sintering. Firework‐like ZrO2 microcrystallites formed by dendritic growth were observed close to the cathode region, which was attributed to athermal electric field effects and the formation and aggregation of oxygen vacancies at the cathode region. The results would provide guidance for fabricating CACNs via flash sintering.

P‐215: Emission Mechanism‐Tunned Fused Indolo[3,2,1‐jk]carbazole‐based Multiple Resonance Emitters for Long Device Operational Lifetime

In blue organic light‐emitting diodes (OLEDs), the importance of terminal emitters, which determine device operational characteristics, has been grown. Although multiple resonance (MR) type emitters can provide high color purity and high device efficiency, the high triplet energy (ET) of emitters often cause issues on long‐term device operation. In this work, as a solution to implementing stable operation of blue OLEDs, novel emission‐mechanism‐tuned MR type emitters were developed based on fused indolo[3,2,1‐jk]carbazole framework. The molecular structural changes effectively stabilized the ET while maintaining the narrow emission bandwidth. The fabricated blue fluorescent OLED recorded a highquantum efficiency in deep‐blue region of CIEy of 0.075 and device lifetime twice longer than a typical boron type dopant based device. This research establishes the emitter design strategy for extended blue OLEDs.

The promotion mechanism of different nitrogen doping types on the catalytic activity of activated carbon electro-Fenton cathode: Simultaneous promotion of H2O2 generation and phenol degradation ability

Doping with nitrogen atoms can improve the catalytic activity of activated carbon cathodes in electro-Fenton systems, but currently there is a lack of understanding of the catalytic mechanism, which limits the further development of high-performance activated carbon cathodes. Here, a multi-scale exploration was conducted using density functional theory and experimental methods to investigate the mechanism of different nitrogen doping types promoting the redox performance of activated carbon cathodes and the degradation of phenol. The density functional theory results indicate that the introduction of nitrogen atoms enhances the binding ability between carbon substrates and oxygen-containing substances, promotes the localization of surrounding electrons, and makes it easier for O2 to bind with protons and catalyze the hydrogenation reaction of *OOH. Due to its weak binding ability with oxygen-containing substances, AC is difficult to form H2O2, resulting in a tendency towards the 4e−ORR pathway. The binding energy between graphite-N carbon substrate and pyridine-N carbon substrate with *OOH is closer to the volcano top, so graphite n and pyridine n can better promote the selectivity of activated carbon for 2e-ORR. In addition, the calculation results also indicate that pyrrole-N and graphite-N are more capable of catalyzing the reaction energy barrier between ·OH and phenol. Finally, the simulation results were used to guide the modification of nitrogen doped activated carbon and experimental verification was carried out. The degradation results of phenol confirmed the efficient synergistic effect between different types of nitrogen doping, and the NAC-800 electrode exhibited efficient and stable characteristics. This work provides a guiding strategy for further developing stable and highly selective activated carbon cathode materials.

Investigation of Doping Effects on the Local Electrochemical Activity of Transition Metal Dichalcogenides 2D Materials

AbstractFinding strategies to enhance catalysts’ electrochemical activity is based on controlling the material design. Bidimensional materials (2DM) such as MoS2 are explored as catalysts for the hydrogen evolution reaction (HER). A comprehensive study of the effects of doping 2D materials with transition metals based on theoretical predictions in tandem with experimental investigation correlates the doping type to the changes in the electronic and electrochemical activity. Localized electrochemical maps obtained by scanning electrochemical cell microscopy (SECCM) reveal that Ti‐doping induces a heterogeneous increase in 2H‐MoS2 basal plane electrochemical activity, while Ni‐doping induces a homogeneous decrease. Additionally, Kelvin probe microscopy provides insight into Ti‐doping, showcasing a decline in the 2H‐MoS2 work function, therefore confirming the predictions from density functional theory simulations. In essence, the findings underscore the potential of transition metal coordination on the 2H‐MoS2 surface as an attractive method for locally doping 2D materials with minimal damage to the crystalline lattice, consequently enhancing the electrochemical activity on the material's basal plane.

C2H2 selective hydrogenation over metal-doped CeO2 catalysts: Unraveling the role of metal and surface frustrated Lewis acid-base pair in tuning catalytic performance

Doping the second metal into CeO2 is used as a generally regarded strategy to promote C2H2 selective hydrogenation. This work employs DFT calculations and microkinetic modeling to explore the performance of CeO2 doped with different Cu, Ni, Pd, Pt, or Co atom towards C2H2 selective hydrogenation. The results show that the doped metal not only promotes the formation of surface oxygen-vacancy, but also generate different types of FLPs with surface O atom. FLPs promote H2 heterolytic dissociation to produce Ce-H/M-H and O-H species. Different forms of surface H species affect the performance of C2H2 selective hydrogenation. C2H4 selectivity follows a U-shaped dependence on surface Ce atom charge transfer amount. The screened catalyst Co/CeO2 presents excellent C2H4 production activity and selectivity, which could well prevent the generation of green oil. This work provides new insights for designing highly efficient metal-doped CeO2 catalysts by tuning the doped metal type.

Changes in crystal morphology induced by lanthanide doping into diacetylene lamellar crystals

In this study, we show that doping lanthanides into lamellar crystals reorganizes the lamellar structure and dramatically changes the crystal morphology. Azo-DA, a compound with azobenzene derivatives and carboxylic acids at both ends of the diacetylene moiety, formed plate-like lamellar crystals. The doping of holmium (Ho), a lanthanide, into the film obtained by stacking Azo-DA lamellar crystals, promoted a dramatic change in crystal morphology, resulting in the formation of an Azo-DA/Ho film with a radial lamellar crystal structure. A detailed investigation of the crystal growth process revealed that Azo-DA/Ho, which is slightly formed in the solution phase during Ho doping, acts as a pseudonucleating agent and dramatically changes the morphology of the lamellar crystals. Additionally, the morphological changes in the lamellar crystal films significantly changed the surface properties of the films, such as their appearance and water repellency. Similar morphological changes in lamellar crystals were induced when other lanthanide elements were used instead of Ho, and the type of lanthanide dopant can affect the magnetic properties of the films.

OPTIMIZATION OF GEOMETRY OF PIEZORESISTIVE EFFECT ON THE EXAMPLE OF CUBIC CRYSTALS

On the example of semiconductor crystals Ge, Si, PbTe, PbS, InSb with different levels of doping and different types of conductivity, the geometry of the piezoresistive effect was optimized, namely, such directions of voltage measuring and uniaxial pressure applying were determined, which ensure the maximum achievable value of the effect. The optimization is based on an approach using the construction and analysis of extreme surfaces that represent all possible maxima of the objective function (the magnitude of the effect) under different spatial orientations of interacting factors. The optimization parameters were the angles that determine the directions of the unit vectors of the directions of current and uniaxial pressure applying. The directions of the radius vectors of the points on the extreme surface coincide with the ones in which the electric voltage is measured, and the length of this radius vector for each point was determined by setting such optimization parameters for which the magnitude of the effect for a given direction of voltage measuring would be maximal. It is shown that the optimal interaction geometry in most of the studied cases is longitudinal, and only for n-PbTe, p-InSb crystals it is transverse (although not identical), and the optimal directions for the studied crystals are <100>, <110> or <111> depending on the composition of the crystal and the type of doping. Despite the fact that all investigated crystals belong to the same point symmetry group (m3m), the shapes of the extreme surfaces for them are significantly different, which is caused by different ratios between the piezoresistive coefficients. Typical forms of extreme surfaces have been identified, and in order to explain the obtained results, an analysis of limiting cases that differ in the ratio of piezoresistive coefficients has been carried out. Based on this analysis, four main types of extreme surfaces were established. A scheme has been built that allows, in the case of cubic crystals, to estimate the type of extreme surface and the corresponding optimal directions of voltage measuring, current density (for cubic crystals, these directions coincide) and uniaxial pressure applying. On the basis of this scheme, the forms of extreme surfaces obtained for the investigated crystals are explained.

Fabrication of penetrating pores in epitaxial Ge-on-Si through preferential etching along threading dislocations

Epitaxial Ge-on-Si possesses a high density of threading dislocations (TDs) due to the lattice mismatch and difference in thermal expansion coefficient. By employing the lattice distortion at the TDs, we demonstrate that penetrating pores along TDs can be formed in both p- and n-type heteroepitaxial Ge layers through a preferential etching. It has been found that the preferential etching at TD sites takes place in the porosification process of Ge-on-Si samples and is independent of the doping type and concentration. The penetrating pores follow the path of the TD lines and can penetrate the entire Ge layer of 1.3 μm to further porosificate the Si substrate. The effects of anodic current density and total etching duration have been thoroughly investigated on forming penetrating pores at TD sites. The dissolution mechanism in the porosification process has been revealed by dissolution valence calculation and recorded potential curves. Our findings shed light on Ge perforation in both p- and n-type Ge-on-Si and show great potential in Si-based integrated photonics and microelectronics.

Uniform Tendency of Surface Dipoles Across Silicon Doping Levels and Types of H‐Terminated Surfaces

AbstractThe termination of surface‐dangling bonds on silicon through hydrogen atoms, also known as Si–H, can achieve chemical passivation and reduce surface states in the electronic bandgap, thus altering electronic properties. Through a comprehensive study of doping levels (1014–1020 cm−3) and types (n and p), a consistent surface dipole trend induced by Si–H termination is discovered. It is achieved by redistributing surface charges and establishing thermal equilibrium with the chemical bond. To resolve this, the surface work function, surface electron affinity, and the energy difference between the valence band and the Fermi level are measured by employing the Kelvin probe, X‐ray photoelectron spectroscopy, and photoelectron yield spectroscopy methods. These findings are further validated through ab initio simulations. This finding has immense implications not only for eliminating electronic defects at semiconductor interfaces, which is crucial in microelectronics but also for developing and engineering hybrid interfaces and heterojunctions with controlled electronic properties.

Effects of graphene doping and gas adsorption on the peak positions of graphene plasmon resonance and adsorbate infrared absorption

The peak positions of graphene plasmon resonance can be controlled to overlap with those of the infrared absorption spectra of gas molecules, allowing highly sensitive detection and identification by graphene nanoribbons. In this study, we investigate the adsorption of gas molecules, including SO2, SO3, H2S, and NH3, on graphene and characterize its effects on the relative positions of the two peaks using density functional theory and the finite difference time domain method. It is demonstrated that the binding energies are stronger, and the amounts of charge transfer are greater in the case of SO2 and SO3 adsorbed on n-doped graphene than in other cases. Electron acceptance by SO2 and SO3 adsorbates on n-doped graphene redshifts the graphene plasmon resonance peaks and their stretching and wagging infrared absorption peaks. However, the former is significantly further redshifted, leading to narrower peak-position-matching ribbon widths in n-doped graphene than in p-doped graphene. The amounts of charge transfer are relatively small regardless of the doping type in the case of NH3 and H2S, mitigating the doping-type dependence compared to SO2 and SO3. The wagging peaks of NH3 on n-doped graphene are shown to be further blueshifted than on p-doped graphene, rendering their peak-position-matching ribbon widths further closer to each other. These results suggest that the effects of doping and adsorption on the two types of peaks should be considered to optimize the performance of graphene plasmon-based gas sensing and identification.

Type-dependent hot carrier behavior in photoelectrochemical reduction and oxidation of Au/GaN junction photoelectrodes

In junctions with semiconductors, plasmonic metal nanoparticles (NPs) can be utilized to efficiently harness solar energy by collecting hot carriers. However, the behavior of hot carriers at the interfaces between semiconductors with opposite doping types is not fully elucidated. Here, Au NPs are attached to n-doped (Au/n-GaN) or p-doped gallium nitrides (Au/p-GaN) to examine the photoelectrochemical performance regarding hot carrier behavior. Direct surface potential measurements revealed that electrons are collected in n-type GaN (n-GaN) when illuminated, while hot holes remain in Au NPs for oxidation reactions via the plasmonic process. Conversely, holes are collected in p-type GaN (p-GaN), thereby promoting the reduction reaction by the electrons left in Au NPs. Specifically, the change in surface potential difference induced by green light illumination in Au/p-GaN is four times greater than that observed in Au/n-GaN. Conversely, the changes in open-circuit potential and photocurrent density under light illumination are approximately six times more significant in Au/n-GaN compared to Au/p-GaN. This difference in efficiency can be attributed to the more favorable oxidation reaction occurring in Au NPs at the interface with GaN materials, as opposed to the reduction reaction, due to the difference in band alignment between the Au/GaN junction systems.

High content pyridine nitrogen-doped carbon nanosheets derived from ZIF-L as anode materials of lithium-ion batteries with excellent capacity and rate performance

The precise control of nitrogen doping types in carbon materials is crucial for optimizing energy storage devices. In this study, we synthesize nitrogen-doped carbon nanosheets (NCS) using ZIF-L as a precursor. Comparatively, the two-dimensional crystal structure of ZIF-L provides several advantages over ZIF-8 as a precursor in terms of nitrogen doping efficiency, achieving a higher doping level (14.56 %) and an increased ratio of pyridinic nitrogen (53.60 %). Consequently, NCS display a greater capacity for pseudocapacitive lithium storage. Furthermore, by adjusting the carbonization temperature, we precisely tailor the graphite-nitrogen doping level of NCS within the range of 16.80–31.22 %. Remarkably, when employed as an anode material in lithium-ion batteries, NCS-800 demonstrates exceptional cycling stability, with a capacity retention of 1078 mAh g−1 after 500 cycles at a current density of 0.5 A g−1, as well as excellent rate capability (735 mAh g−1 at 5 A g−1). This study not only compares the impact of precursor crystal structure modifications on nitrogen doping and lithium storage performance but also introduces a novel synthesis methodology for highly nitrogen-doped carbon materials, offering new avenues for future research in this field.

Effect of films thickness and hydrogen annealing on passivation performance of plasma ALD based Hafnium oxide films

We investigate the silicon surface passivation property of Plasma Atomic Layer Deposited (PALD) hafnium oxide thin films and study its dependence on silicon (Si) doping type, film thickness, and post-deposition annealing conditions. Our results demonstrate that as-deposited HfOx films exhibit poor passivation quality that can be improved by performing post-deposition annealing at 450 °C in hydrogen ambient. We demonstrate that the films can effectively passivate p-Si surfaces as compared to n-Si, where the surface passivation quality of the films improves with increasing film thickness for both silicon doping types. The best performance with a minority carrier lifetime of 1.7 ms, corresponding surface recombination velocity (SRV) ∼10 cm s−1, is achieved for HfOx films thickness ∼23 nm deposited on the p-Si substrate. The Capacitance-Voltage (C–V) measurements give an insight into the passivation mechanism of the studied films. Field effect passivation is found to be an important passivation mechanism in PALD-deposited HfOx films, as revealed by C–V measurements. The films are also characterized using Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS), which reveals the chemical passivation provided by hydrogen ambient annealing. Overall, the impact of hafnium oxide film thickness and hydrogen ambient annealing conditions on silicon surface passivation is investigated. Our findings will help in utilizing plasma ALD process based HfOx films for silicon solar cell device application.

Growth and superconductivity of the Kagome metal CsV3(Sb1-xSex)5 single crystals

In this Letter, CsV3(Sb1-xSex)5 (0 ≤ x ≤ 0.1) crystals were grown using a Sb-rich self-flux method, and studied by XRD, Laue Diffraction, SEM, EDS, and magnetization measurements. It was found that at low doping concentration (x≤ 0.08), the crystal has good quality, and the nominal and actual components are basically consistent. At x = 0.1, the crystal quality decreases, and the actual doping amount starts to be slightly lower than the nominal value. Se doping suppresses superconducting transition due to its band filling effect and negative chemical pressure effect on CsV3Sb5. In addition, Se doping also has an inhibitory effect on the CDW transition in CsV3Sb5. Compared with hole type dopants, this electronic type dopant has a weaker inhibitory effect on TCDW, indicating an asymmetric response of electronic characteristics to carrier charge symbols in the system.

Enhancing piezoelectric performance of CNTs through B and N substitution under combined mechanical loads: insights from MD simulations

The piezoelectric properties of carbon nanotubes (CNTs) doped with boron (B) and nitrogen (N) were studied using the classical molecular dynamics (MD) simulation software package large scale atomic/molecular massively parallel simulator. The interactions among the nanotube atoms C, N, and B were calculated using the Tersoff potential. MD simulations were performed to observe the changes in the piezoelectric coefficient of the doped CNTs under loading conditions like tension, torsion, and a combination of both. We considered a wide range of chirality to determine the influence of structural variation on the piezoelectric effect. The study revealed that B-CNTs exhibit superior piezoelectric coefficients compared to N-CNTs, indicating the significant role of dopant type. Moreover, under tensile loading, zigzag-oriented B-CNTs showed higher piezoelectric coefficients with a maximum e33 = 0.2441 C m−2, whereas under torsional loading, armchair-oriented B-CNTs showed enhanced response with a maximum e36 = 0.0564 C m−2. A notable observation was that under combined loading conditions (tensile and torsional), the piezoelectric behavior of the B-CNTs was dependent on the nanotube’s chirality and did not yield a linear additive response. The polarization induced under combined loading in most of the doped CNTs is significantly higher than the sum of polarization generated under tensile and torsional loading conditions. This behavior suggests that the overall piezoelectric effect under combined loading can be enhanced, which emphasizes the need for an approach to optimize the mechanical loading condition. The results showcase the potential of B-/N-CNTs to be engineered for efficient performance by demonstrating that tailored mechanical loading can enhance the piezoelectric responses in doped CNTs, opening a pathway for highly functional and efficient nanoscale piezoelectric devices.

Development of a novel fluorescence spectroscopy based method using layered double hydroxides to study degradation of E. coli in water

Layered double hydroxides (LDHs) belong to a class of 2D nanomaterials having metallic ions of varying valences and interlayer spacing as in brucite. Since their discovery, they are being used everywhere. However, their biomedical properties are the most explored as they exhibit advantages like biodegradability, biocompatibility, and ease of making composites. In this research, two types of LDHs i.e. MgAl and ZnAl LDHs are synthesized via hydrothermal route. Two types of doping; Gd and Yb, are done to create GdMgAl, GdZnAl, YbMgAl and YbZnAl. After synthesis, LDHs are characterized by X-ray Diffraction, Scanning Electron Microscopy, Dynamic Light Scattering, Energy dispersive X-ray Spectroscopy, and UV–vis spectroscopy. Average length for LDHs was found out to be in the range of 275–467 nm whereas thickness was in between 67 nm and 135 nm via SEM. Hydrodynamic size came out to be between 331 nm and 1720 nm for all samples. Absorption wavelength for all samples was between 251 and 261 nm. A novel antibacterial approach utilizing LDHs was introduced, employing antibacterial photodynamic treatment. The results were quantified using fluorescence spectroscopy, taking tryptophan peak as bacterial indicator at 270 nm excitation. Spectra recorded in 285–550 nm range showed considerable bacterial degradation, notably with YbZnAl LDHs. The efficacy was further tested with Colony Forming Units. Notably, all synthesized particles outperformed UV light alone, demonstrating their versatility as photocatalysts for bacterial inactivation. This pioneering method provides a unique and effective strategy for antibacterial treatment.

Fabrication of flexible paper-based conducting molecularly imprinted polymer as analytical devices: Electrochemically assisted solid phase microextraction and selective flexible sensor for determination of naproxen

An electrochemical method is presented for the preparation of paper-based conductive molecular imprinted polymer (CMIP) film as a recognition element of a sensor and a selective absorber in separation methods. The paper became conductive by chemically incorporating polypyrrole (PPy) doped with anion dopant. The effects of the anion dopant and oxidant type on the conductivity of the modified paper were studied. Afterward, a CMIP film based on PPy and an anionic drug as a template was electrochemically synthesized on conductive paper surface, which was then utilized as a selective sorbent for electrochemically assisted solid phase microextraction (EC-SPME) and a recognition element in fabricating flexible drug-selective sensor. Factors affecting the performance of the paper-based EC-SPME device were studied in naproxen (NAP) analysis. All quantitative analytical parameters in the EC-SPME device were obtained by UV–vis absorption spectroscopy. Under the optimal conditions, linearity was achieved within the range of 2.0 × 10−7–2.0 × 10−5 mol/L with determination coefficient (R2 = 0.99) and the limit of detection (LOD) was 0.6 × 10−7mol/L. Moreover, a fabricated paper-based NAP-selective sensor, showed Nernstian response slopes of −61.6 ± 0.5 mV decade−1 over the linear range of 4.0 × 10−7–1.0 × 10−2 mol/L and LOD was 2.0 × 10−7 mol/L. The applicability and efficiency of the paper-based analytical devices were investigated for NAP determination as a model drug in human serum samples. The recoveries were obtained in the range of 90.0–103.0 %. Accordingly, paper-based CMIPs were found to be a novel fabrication method for efficient, selective, flexible and cost-effective material for analytical devices.

Synthesis of N-doped graphene film with tunable graphitic and pyridinic doping content

Nitrogen-doped (N-doped) graphene films with up to a 17.39 at.% doping level were synthesized with the chemical vapor deposition growth method. An extensive range of tunable nitrogen doping levels was achieved by selecting organic molecules as precursors grown at a wide temperature range of 300 to 1000 °C. The benzene rings in the precursor significantly reduced the energy requirements of N-doped graphene. The incorporation of bridgehead nitrogen and amino groups ensured a high nitrogen doping level and offered the tunable modulation of nitrogen dopant concentrations. The influence of temperature on the nitrogen content was investigated, distinguishing the graphitic and pyridinic dopant types, each demonstrating unique trends considering the dopant stability and growth mechanism. Specifically, the proportion of graphitic doping could be modulated from 40 % to 100 %. Notably, the pyrrolic type was absent at lower temperatures and was nearly negligible at elevated temperatures. Therefore, we developed a synthesis method for N-doped graphene growth that allowed for the selective and prioritized tuning of nitrogen dopant types. This method is particularly favorable when specific nitrogen dopants at certain doping levels are required for electrical and chemical catalytic applications.

Gamma-ray shielding effectiveness, thermal, and dielectric properties of filler-reinforced high-density polyethylene/boron carbide composites

The present research prepared samples of pure high-density polyethylene (HDPE)/boron carbide reinforced with iron dioxide, aluminum dioxide, iron, and aluminum. The effectiveness of the prepared samples as a shielding material against gamma-rays and their thermal and dielectric properties have been evaluated. The shielding characteristics of the prepared composites were investigated theoretically using the Phy-X/PSD program and experimentally for gamma-rays emitted from 131Cs and 60Co radioactive isotopes. The shielding evaluation included the mass attenuation coefficient (μ/ρ), half value layer (HVL), mean free path (MFP), atomic and electronic cross-sections (σa&σe), effective atomic number and electron density (Zeff &Neff), and exposure build-up factor (EBF). The EBF peaks of samples containing Fe and Fe2O3 are 103 times lower than pure HDPE. The results indicate that samples C2 and C3 have a higher ability to protect against gamma radiation than that of the other investigated samples. X-ray diffractometer (XRD) spectrum shows that adding B4C, Fe, Fe2O3, Al, and Al2O3 to HDPE caused an increase in its full width at half maximum (FWHM) value and a decrease in its average crystallite diameters (D) at its primary characteristic scattering angle of 21.49°. Adding multiple types of fillers to HDPE results in a minor shift in the melting temperature of the hosting matrix as proved from differential scanning calorimetry (DSC) data. The composite of HDPE/B4C/Al2O3 60/10/30 demonstrated the most significant values of dielectric parameters in comparison with the other composites, in good accord with the XRD results. The ac conductivity relied on the dopant type in the hosting matrix; the highest value was observed for HDPE/B4C/Al2O3 composite.

Effects of transition metals (Nb, Mo and Cd) and main group metals (In, Ge and Sb) on mechanical properties of Al2Cu: A first-principles study

It is well known that two significant ways to influence the properties of Al-Cu alloys are strengthening phases and doping. In order to investigate the effect of doped atomic types on the performance of reinforced phase θ (Al2Cu), first-principles calculations based on density-functional theory are used to investigate the elastic constants and electronic structures of the Al-Cu-X (X= Nb, Mo, Cd, Ge, In, and Sb) doped systems. The results show that, different types of doped atoms have different effects on the mechanical properties and bonding characteristics of Al2Cu. The transition metals (Nb, Mo, and Cd) cause Al2Cu to form metallic bonding. Due to the physical properties of the metallic bonding, the doped structures have better plasticity than the θ phase. On the contrary, the main group metals (In, Ge and Sb) cause Al2Cu to form strong covalent bonding. Due to the physical properties of the covalent bonding, the strength of the doped structures is better than the θ phase.