Effect Of Cu Doping Research Articles

Multifunctional properties in both three and one-dimensional polycrystalline Cu-doped Co–Ni-Ga shape memory alloys

The effect of Cu doping on the microstructure and functional properties of polycrystalline Co–Ni-Ga-Cu shape memory alloy is investigated with the Cu composition ranging from 0.3 to 4.5 at.%. For the miniaturization applications in actuators and sensors, the alloy with 3 at.% Cu is selected to fabricate one-dimensional microwires. The results reveal that Cu promotes the growth of the γ phase precipitates, accompanied by the decrease of the martensitic transformation temperature in the bulk Co–Ni-Ga-Cu samples. At low Cu doping, a reversible strain of 4% is obtained. By increasing Cu to 4.5%, a compressive reversible strain can reach at least 2.5% at room temperature. During the compression process, the adiabatic elastocaloric effect of a 3.3 K temperature change is also achieved. Furthermore, the polycrystalline microwire displays a great tensile superelasticity with a larger reversible strain of 5% in a temperature range varying from 223 to 373 K, which is the best among Co–Ni-Ga polycrystalline alloys. The shape memory effect of the microwire with a 3% strain output ranging from 123 K to 353 K is achieved as well. The good multifunctional properties in the Co–Ni-Ga-Cu shape memory alloy bulks and microwires lay a foundation for their applications in sensing, actuating and solid-state refrigeration fields.

Evaluation of the Crystal Structure and Mechanical Properties of Cu Doped TiN Films

In this study, TiN films doped with different copper contents (TiCuN) were prepared by using direct current magnetron sputtering method. The effects of Cu doping on composition, structure, and mechanical properties of TiN films were studied by energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), a Vickers microhardnessmeter, and density functional theory (DFT). The results of experimental and DFT study showed that Cu mainly replaced Ti atoms in TiN to form replacement solid solution doping. When Cu replaced Ti in TiN, a weak Cu-N (bond population varied from 0.06 to 0.11) covalent bond formed; meanwhile, the bonding strength of Ti-N (bond population varied from 0.29 to 0.4) bond adjacent to Cu increased. When Cu content was low, a small number of weak Cu-N bonds were formed, with strengthened Ti-N bond near Cu atom, resulting in an increased hardness of Cu doped TiN films. According to the theory of weak bonds, when the Cu content was increased further, the number of weak Cu-N bonds increased and TiCuN hardness decreased. With an increase in Cu content, it was found the toughness of TiCuN also increased. The results of this study will provide a theoretical and experimental guidance for improving the toughness and deformation resistance of TiN, which has a potential application in the surface modification of medical devices.

Effect of Cu Doping on Structure and Physical Properties in the Antiferromagnetic Dirac Semimetal CaMnBi2.

The newly discovered AMnBi2 (A = Ca, Sr, Ba, Eu, and Yb) materials composed of two-dimensional Bi square nets provide an excellent platform to investigate the effect of magnetism on topological band structures. Effectively tuning the magnetic interaction in AMnBi2 is of great importance to advance this issue. Here, we describe an effective route to tune the magnetism in Dirac semimetal CaMnBi2 through Cu doping. Structural analysis on CaMn1-xCuxBi2 single crystals indicates that Cu atoms occupy the Mn sites randomly, with the maximum doping level of 25%. After Cu doping, the Bi square net in charge of the Dirac band is still retained, but the Bi-Bi bond distance is markedly shortened. The antiferromagnetic interaction of CaMnBi2 is strongly weakened in the Cu-doped crystals, with the transition temperature decreased from 260 to 85 K. On the contrary, the ferromagnetic component that originated from the canted AFM is enhanced, suggesting that the spin canting in this system is tunable. In addition, the magnetoresistance is decreased upon Cu doping, probably due to the disorder in structure. Our work suggests that the CaMn1-xCuxBi2 (0 ≤ x ≤ 0.25) system can offer a suitable playground to address the interplay between magnetism and the topological state.

Effects of Cu doping on electrochemical NOx removal by La0.8Sr0.2MnO3 perovskites

Electrochemical removal of nitrogen oxides (NOx) by perovskite electrodes is a promising method due to its low cost, simple operation and no secondary pollution. In this study, a series of La0.8Sr0.2Mn1-xCuxO3 (x = 0, 0.05, 0.1 and 0.15) perovskites are fabricated as the improved electrodes of solid electrolyte cells (SECs) for NOx removal and the effects of Cu doping are investigated systematacially. Multiple characterization methods are carried out to analyze the physicochemical properties of perovskites firstly. Then the performances of cells based on various perovskites are evaluated by the measurements of electrochemical properties and NOx conversions. The results show that the Cu-doped electrode has more surface oxygen vacancies and a better redox property, thus having a higher NOx conversion and smaller polarization resistance. The electrode based on La0.8Sr0.2Mn0.9Cu0.1O3 has the maximum 70.8% NOx conversion and the lowest 36.3 Ω cm2 Rp value in the atmosphere of 1000 ppm NO at 700 °C. First-principle calculation reveals that the Cu-doped electrode is easier to form surface oxygen vacancy, while the surface oxygen vacancy plays an important role on electron transfer between electrode and NOx molecule. This study not only provides a new strategy to enhance the electrode performance for NOx removal in SECs but reveals the fundamental effect of Cu doping on the properties of La0.8Sr0.2MnO3 perovskites.

The effect of Cu doping into Ag in ZnO/Ag/ZnO/SiO2 on reduction of the thermal effect of solar cells

The effect of Cu doping into Ag in ZnO/Ag/ZnO/SiO2 on reduction of the thermal effect of solar cells

Enhanced sintering and electrical properties of proton-conducting electrolytes through Cu doping in BaZr0.5Ce0.3Y0.2O3-δ

To obtain BaZrO3-based electrolyte materials with both good sinterability and high proton conductivity, a Cu-doped B-site BaZr0.5Ce0.3Y0.2-xCuxO3-δ (BZCYCux; x = 0, 0.05, 0.1) system is designed and synthesized. The effects of Cu doping on the crystal structure, sintering and electrical properties of BZCYCux are systematically investigated. The BZCYCu0.05 sample demonstrates the highest sintering density and total conductivity among the studied materials. BZCYCu0.05 can be densified at 1250 °C, which is 300 °C lower than that for unmodified BZCY. The calculated results suggest that the increased conductivity in BZCYCu0.05 benefits from a high apparent specific grain-boundary conductivity, which originates from a small space-charge potential and a large clean part of impurities in the electrolyte. A synthetic analysis based on impedance spectroscopy and distribution of relaxation time further confirms that BZCYCu0.05 is more conductive. A single cell built using the BZCYCu0.05 (∼46 μm) electrolyte shows an excellent power density of 258 mW cm−2 at 700 °C. These results indicate that BZCYCu0.05 is a potential proton conductor for use in protonic ceramic fuel cells.

The Effect of Cu Doping on the Piezoelectric Properties of Zno Systems: First-Principles Calculations

The Effect of Cu Doping on the Piezoelectric Properties of Zno Systems: First-Principles Calculations

Effect of Cu Doping on ZnO Nanoparticles as a Photocatalyst for the Removal of Organic Wastewater.

Environmental problems with chemical and biological water pollution have become a major concern for society. Providing people with safe and affordable water is a grand challenge of the 21st century. The study investigates the photocatalytic degradation capabilities of hydrothermally prepared pure and Cu-doped ZnO nanoparticles (NPs) for the elimination of dye pollutants. A simple, cost-effective hydrothermal process is employed to synthesize the Cu-doped ZnO NPs. The photocatalytic dye degradation activity of the synthesized Cu-doped ZnO NPs is tested by using methylene blue (MB) dye. In addition, the parameters that affect photodegradation efficiency, such as catalyst concentration, starting potential of hydrogen (pH), and dye concentration, were also assessed. The dye degradation is found to be directly proportional to the irradiation time, as 94% of the MB dye is degraded in 2 hrs. Similarly, the dye degradation shows an inverse relation to the MB dye concentration, as the degradation reduced from 94% to 20% when the MB concentration increases from 5 ppm to 80 ppm. The synthesized cost-effective and environmentally friendly Cu-doped ZnO NPs exhibit improved photocatalytic activity against MB dye and can therefore be employed in wastewater treatment materials.

Influences of Sn/Cu single doping and CO-doping on the structure and photocatalytic property of anatase/rutile mixed crystal TiO2 nanomaterials under UV-visible light

Anatase/rutile mixed crystal TiO2 nanomaterials were prepared by sol-gel method and modified by Sn/Cu single doping and co-doping. Sn doping promotes the transformation from anatase to rutile, while Cu doping inhibits the phase transformation. The inhibition effect of Cu doping on phase transition is stronger than that of Sn doping. Sn or Cu doping reduces the recombination rate, and co-doping produces a synergistic effect on the inhibition of recombination. The photocatalytic experiment results show that the photocatalytic activity of Sn-TiO2 is higher than that of pure TiO2 owing to higher quantum efficiency and light source absorption. The first order reaction rate constant increases from 0.00904 min-1 for pure TiO2 to 0.01476 min-1 for Sn-TiO2. Unexpected, the photocatalytic activities of Cu-TiO2 and Sn/Cu-TiO2 are lower than that of pure TiO2. Although Cu doping improves the quantum efficiency, it reduces the absorption of ultraviolet region significantly, which is the key reason for the decline of their photocatalytic performance.

Effect of Cu-doping and thermal treatment on antibacterial potential of ZnS nanoparticles

A zinc sulphide nanoparticle is important metal sulphide nanoparticles (NP) that have drawn much attention since last decades due to their properties which are tunable and thus their applications in various fields. The microorganisms have the ability to develop the drug degrading enzyme over the period of time. This is one of the biggest challenges for the researchers and scientist. ZnS NPs is a potential antibacterial material and thus can prevent the growth of various harmful microbes. We therefore have reported the annealing effect on synthesized Copper doped ZnS (Cu-ZnS) nanoparticles. We have investigated optical properties of Cu-ZnS nanoparticles with UV–Vis spectroscopy and Raman spectroscopy. XRD spectra and FESEM of synthesized sample have also been investigated. The particle size of synthesized nanoparticle that have been calculated by XRD analysis is about 2–18 nm. From UV– Vis spectra, the change in the energy of bandgap of Cu-ZnS NPs towards higher wavelength side observed due to the effect of annealing at different temperature. This research article provides the understanding of treatment of different temperature on Cu-doped ZnS nanoparticles. The synthesized materials exhibited good antibacterial properties against the tested bacterial strains like Escherichia Coli (Ec), Bacillus subtilis (Bs) and Staphylococcus aureus (Sa). We have reported that the antibacterial activity of Cu-ZnS NPs enhanced on increasing the annealing temperature, which make it potential candidate for antibacterial application.

Effects of Cu doping on thermoelectric properties of Al–Si–Ru semiconducting quasicrystalline approximant

We have attempted to improve the thermoelectric performance of an Al--Si--Ru semiconducting approximant through optimizing the carrier concentration. The effects of Cu doping on the thermoelectric properties of an Al--Si--Ru semiconducting quasicrystalline approximant with the nominal composition of ${\mathrm{Al}}_{69\ensuremath{-}0.75x}{\mathrm{Si}}_{7.5}{\mathrm{Cu}}_{x}{\mathrm{Ru}}_{23.5\ensuremath{-}0.25x}\phantom{\rule{4pt}{0ex}}(x=0,2,4,6,8)$ are investigated. At approximately room temperature, an increase of $x$ leads to a decrease of the Seebeck coefficient $S$ and an increase of the electrical conductivity. Density functional theory and the Boltzmann transport theory are used to calculate $S$ as the hole concentration and the band gap are varied. The temperature dependence of $S$ is quantitatively described by an increase of the hole concentration and narrowing of the band gap with increasing $x$. Cu doping is shown to increase the hole concentration and narrow the band gap. The maximum dimensionless figure of merit increases from 0.03 at 400 K for $x=0$ to 0.2 at 500 K for $x=4$. These results indicate that the semiconducting quasicrystalline approximant could be a suitable candidate as a thermoelectric material for low grade waste heat recovery.

Effect of Cu doping on the optical property of green synthesised l-cystein-capped CdSe quantum dots

Abstract In the present study, the synthesis of water-soluble copper-doped CdSe nanoparticles (NPs) via a low cost, facile, and environmentally benign method is reported. Simple reagents such as selenium powder, cadmium chloride, and copper sulphate were used as selenium, cadmium, and copper precursor, respectively, while l-cysteine was used as a capping ligand without the use of an additional stabiliser. The as-synthesised copper-doped CdSe NPs were characterised using ultraviolet (UV-Vis) absorption and photoluminescence (PL) spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. By varying the dopant concentration, the temporal evolution of the optical properties and the shape of the nanocrystals were investigated. The observation and the results showed that the colour of the solution changed rapidly from orange to black, and the PL shifted to a longer wavelength at the high dopant concentration. The micrographic images revealed that the as-synthesised materials are small and could be used for bio labelling.

The effect of Cu doping on optical and surface properties of ZnO thin films fabricated by thermionic vacuum arc (TVA) deposition

The effect of Cu doping on optical and surface properties of ZnO thin films fabricated by thermionic vacuum arc (TVA) deposition

H2S and SO2 adsorption on Cu doped MoSe2: DFT investigation

Hydrogen sulfide and sulfur dioxide are highly hazardous gases, thus, the development of highly sensitive and selective materials for their adsorption is desirable. The effect of Cu doping of MoSe2 on its adsorption for both H2S and SO2 gases is investigated in this work using first principles density functional theory (DFT) computations. The band gap, adsorption distance, adsorption energy, density of states, and charge transfer are examined in details. The results illustrate significant changes of the electronic properties as well as adsorption for H2S and SO2 gases of MoSe2 due to doping with Cu. The results reveal significant changes in the density of states and band gap upon doping with Cu that enhance the adsorption of both H2S and SO2 gases on MoSe2 system. Nevertheless, the Cu-modified MoSe2 system exhibits higher adsorption energy towards H2S thus higher sensitivity as compared with SO2. The results demonstrate that the Cu-modified MoSe2 system can be applied successfully for H2S gas sensor applications.

Highly Conductive Mn-Co Spinel Powder Prepared by Cu-Doping Used for Interconnect Protection of SOFC

Mn-Co Spinel is considered as one of the most promising materials for the interconnect protection of solid oxide fuel cells; however, its conductivity is too low to maintain a high cell performance as compared with cathode materials. Element doping is an effective method to improve the spinel conductivity. In this work, we proposed doping Mn-Co spinel powder with Cu via a solid phase reaction. CuδMn1.5−xCo1.5−yO4 with δ = 0.1, 0.2, 0.3, and x + y = δ was obtained. X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TG-DSC) were used to evaluate the Cu-doping effect. After sintering at 1000 °C for 12 h, the yield exhibited the best crystallinity, density, and element distribution, with a phase composition of MnCo2O4/CuxMn3−xO4 (x = 1, 1.2, 1.4 or 1.5). X-ray photoelectron spectroscopy (XPS) was used to semi-quantitatively characterize the content changes in element valence states. The areal fraction of Mn2+ and Co3+ was found to decrease when the sintering duration increased, which was attributed to the decomposition of the MnCo2O4 phase. Finally, coatings were prepared by atmospheric plasma spraying with doped spinel powders and the raw powder Mn1.5Co1.5O4. It was found that Cu doping can effectively increase the conductivity of Mn-Co spinel coatings from 23 S/cm to 51 S/cm. Although the dopant Cu was found to be enriched on the surface of the coatings after the conductivity measurement, which restrained the doping effect, Cu doping remains a convenient method to significantly promote the conductivity of spinel coatings for SOFC applications.

Effect of Cu doping on the secondary electron yield of carbon films on Ag-plated aluminum alloy

Reducing the secondary electron yield (SEY) of Ag-plated aluminum alloy is important for high-power microwave components. In this work, Cu doped carbon films are prepared and the secondary electron emission characteristics are studied systematically. The secondary electron coefficient δ max of carbon films increases with the Cu contents increasing at first, and then decreases to 1.53 at a high doping ratio of 0.645. From the viewpoint of surface structure, the higher the content of Cu is, the rougher the surface is, since more cluster particles appear on the surface due to the small solid solubility of Cu in the amorphous carbon network. However, from viewpoint of the electronic structure, the reduction of the sp2 hybrid bonds will increase the SEY effect as the content of Cu increases, due to the decreasing probability of collision with free electrons. Thus, the two mechanisms would compete and coexist to affect the SEY characteristics in Cu doped carbon films.

Bandgap Modulation of Cs2AgInX6 (X = Cl and Br) Double Perovskite Nano- and Microcrystals via Cu2+ Doping.

Recently, the double perovskite Cs2AgInCl6, which has high stability and low toxicity, has been proposed as a potential alternative to Pb-based perovskites. However, the calculated parity-allowed transition bandgap of Cs2AgInCl6 is 4.25 eV; this wide bandgap makes it difficult to use as an efficient solar absorber. In this study, we explored the effect of Cu doping on the optical properties of Cs2AgInCl6 double perovskite nano- and microcrystals (MCs), particularly in its changes of absorption profile from the ultraviolet (UV) to near-infrared (NIR) region. Undoped Cs2AgInCl6 showed the expected wide bandgap absorbance, but the Cu-doped sample showed a new sharp absorption peak at 419 nm and broad absorption bands near 930 nm, indicating bandgap reduction. Electron paramagnetic resonance (EPR) spectroscopy demonstrated that this bandgap reduction effect was due to the Cu doping in the double perovskite and confirmed that the Cu2+ paramagnetic centers were located on the surface of the nanocrystals (NCs) and at the center of the perovskite octahedrons (g∥ > g⊥ > ge). Finally, we synthesized Cu-doped Cs2AgInCl6 MCs and observed results similar to those of the NCs, showing that the application range could be expanded to multidimensions.

Investigation of spray pyrolyzed cubic structured Cu doped SnS films

Undoped and Cu doped SnS films were deposited onto glass substrates by spray pyrolysis technique in order to investigate the effect of Cu doping on their physical properties. Surface investigations showed that Cu doping reduced the surface roughness of SnS films from 36.5 to 8.8 nm. XRD studies revealed that all films have recently solved large cubic phase of SnS (π-SnS) with a-lattice of 11.53 Å and Cu doping led to a reduction in crystallite size from 229 to 198 Å. Additionally, all deposited films were found to be under compressive strain. Optical band gaps of SnS:Cu varied in the range of 1.83–1.90 eV. Hall-effect measurements exhibited that all films have p-type conductivity with low hole concentration (∼1011–1012 cm−3) and high electrical resistivity (∼104–105 Ωcm).

Effects of Cu doping on the phase transition and photocatalytic activity of anatase/rutile mixed crystal TiO2 nanocomposites

Pure and Cu doped anatase/rutile mixed TiO2 nanomaterials were fabricated through sol-gel method. The obtained photocatalysts were characterized by XRD, SEM, TEM, XPS, PL and DRS, and the influences of Cu doping on the structure and photocatalytic property were studied. The results show that when the molar ratios of Cu/Ti are 1% and 2%, Cu doping promotes anatase → rutile phase transformation. When the molar ratio of Cu/Ti is 4%, the phase transformation is inhibited. Cu element coexists in the form of Cu+ and Cu2+, and Cu doping facilitates the separation of photogenerated electrons and holes. TEM image shows that copper oxides are dispersed on TiO2 particles surface, which significantly reduces the optical absorption of ultraviolet region. The photocatalytic experiment results show that the photocatalytic activity of Cu–TiO2 is lower than pure TiO2, and the higher doping concentration, the lower photocatalytic activity.

Magnetic properties evolution with grain boundary phase transformation and their growth in Nd-Fe-Cu-Ga-B sintered magnet during post-sinter annealing process

The formation of Nd6Fe13Ga phase promoted the continuity and non-ferromagnetism of grain boundary (GB) phases of Nd-Fe-Cu-Ga-B magnets during proper post-sintering annealing process. The coercivity increased dramatically with a decrease of remanence. After further annealing at the sintering temperature, the remanence recovered with a drop of coercivity. It indicated that Nd2Fe14B phase decomposed with the formation of Nd6Fe13Ga phase. Overextending the annealing time led to the gradual decrease of coercivity as the growth of Nd6Fe13Ga phase weakened the continuity of GB phases. Increasing the annealing temperature to the optimum temperature for Nd6Fe13Ga phase can aggravate the decrease of coercivity and remanence. Owing to the intensifying segregation of Ga and Fe in GB phases with the formation of Nd6Fe13Ga phase by dehydrogenation (HD) at 560 °C, high coercivity can be obtained by annealing at a lower temperature or for shorter time compared with HD at 480 °C. The enrichment of Cu in Nd-rich phase ensured its wettability and non-ferromagnetism when the diffusion of Fe and Ga became more local with the formation of Nd6Fe13Ga phase. Therefore, the combined effect of Cu doping and reasonable high temperature HD was conducive to obtain high coercivity in a larger range of annealing time and temperature for Nd-Fe-Ga-B magnet, which was a potential method for its mass production.