Effect Of CuO Addition Research Articles

Influence of CuO addition on the sintering temperature and giant dielectric properties of (In0.5Nb0.5)0.05Ti0.95O2 ceramics

Co-doped TiO2 ceramics exhibit great potential as high-performance giant dielectric materials. However, their excessively high sintering temperature renders them unsuitable for economical industrial production. The giant permittivity of these ceramics is closely correlated with the concentration of Ti3+ ions present. Adding a sintering aid to the ceramics is an effective method to reduce the sintering temperature. CuO, a common sintering aid, not only reduces the sintering temperature but also potentially enhances the Ti3+ ions concentration through the multivalence of Cu element, further optimizing their giant dielectric properties. Therefore, the effects of CuO addition on the sintering condition, microstructure, and dielectric properties of In and Nb co-doped TiO2 ceramics were investigated. The results indicate that CuO effectively lowers the sintering temperature of the ceramics. However, the presence of a large number of Cu+ ions inhibits the formation of Ti3+ ions, resulting in the disappearance of their giant dielectric properties. Upon annealing at 1150 °C for 2 h in air, the Ti3+ ions concentration significantly increases in the ceramics, consequently restoring their giant dielectric properties. Additionally, a new dielectric relaxation appears around 100 kHz, likely arising from the conductivity difference between the shallow layers and cores of grains induced by annealing. Furthermore, annealing enhances the grain boundary resistance, thereby reducing the low-frequency dielectric loss of the ceramics.

Effect of CuO addition on the structural, electrical and dielectric properties of the sodium borate glasses

The sodium borate glasses doped with different CuO content (70B2O3˗30Na2O˗xCuO with x = 0, 2, 4, 6 and 8 mol%) have been prepared using the conventional melt-quenching technique. The amorphous nature of the prepared samples has been identified by X-ray diffraction (XRD). The experimental and theoretical density, the molar volume, and the oxygen packing density have been defined. The effect of CuO incorporation into the 70B2O3˗30Na2O glass base on the electrical and dielectric properties has been studied. The D.C. electrical parameters have been measured in the temperature range 323˗483 K, while the dielectric parameters have been measured in the temperature range 333˗483 K and the frequency range 10−1˗ 107 Hz. The D.C. electrical conductivity increases while the activation energy decreases by increasing CuO content (mol%). The conduction type is ionic which CuO inserts into the glass structure as a glass modifier. The A.C. study reveals that all investigated glasses obey the correlated barrier hopping model (CBH). Moreover, the dissipation factor peaks indicate the glasses' relaxation nature which has been further analyzed from the real and imaginary parts of the electric modulus.

Effect of CuO addition on the performance of V2O5-based oxygen carriers for chemical-looping oxidation of H2S for efficient sulfur recovery from natural gas

Integrating Chemical-Looping process with Selective Oxidation of H2S (CLSO) at low temperature is a novel method to achieve efficient desulphurization and sulfur recovery from nature gas. In CLSO process, a reducible catalytic oxygen carrier (COC) is need to cyclically transport oxygen from air to H2S in gaseous fuels. For energy saving, it must have adequate catalytic sites that can selectively convert H2S to elemental sulfur at temperature as low as possible, meanwhile COCs do not combust nature gas, and for continuously operation the reduced COCs can be fully regenerated with air. COC development is key issue for the successful deploying CLSO process. Based on CLSO concept given by previous work (Kane, 2019), this study developed various V2O5-based COCs with and without CuO addition using TiO2- and Al2O3- supports of stableporousstructures, trying to improve the overall performance of COCs. By cyclic CLSO experiments, the desirable features of the new COCs were examined, and the effects of CuO addition on oxygen transport, catalytic behaviors, and chemical stabilities were specially assessed. This study also revealed the selective oxidation reaction mechanisms of H2S with these V2O5-based COCs, and identified the roles of CuO in catalytic redox reaction. It is demonstrated that the reactivities of V2O5 phase was greatly promoted as supported on porous supports; CuO phase enhanced significantly oxygen transport capacities of COCs as it was reduced to metallic copper in selective oxidation of H2S. Elemental sulfur deposition, H2S adsorption, and metallic sulfide formation put impacts to selectivity, and further study to improve COC selectivity is needed.

Evolutions in the microstructure and ionic conductivity of CuO-doped yttria-stabilized zirconia

The effect of CuO addition on the microstructure and ionic conductivity of 8 ​mol% yttria-stabilized zirconia (8YSZ) were investigated. Undoped and 1 ​mol%, 1.5 ​mol%, 2 ​mol%, 2.5 ​mol% and 3 ​mol% CuO-doped 8YSZ bulks were prepared by sol-gel synthesis, cold pressing forming, and high-temperature sintering. The microstructure, phase composition, and ionic conductivity of the samples were characterized in detail to determine whether it could be used as alternative electrolyte material for the intermediate and low temperature solid oxide fuel cells. The results reveal that all samples present cubic zirconia. With increasing the CuO-doping content, the lattice parameter of the samples decreases, while the relative density of the samples increases from 66 to 85%, and the mean grain size increases from 0.90 to 2.63 ​μm. Furthermore, it is found that 2 ​mol% CuO doped 8YSZ possesses the minimum activation energy of 0.945 ​eV and the maximum AC ionic conductivity of 5.75 ​× ​10−2 ​S·cm−1 measured at 750 ​°C. The change in the ionic conductivity with the CuO-doping content is closely related to microstructural evolution and defect association in the materials.

Effect of Cuo Addition on the Performance of V2o5-Based Oxygen Carriers for Chemical-Looping Oxidation of H2s for Efficient Sulfur Recovery from Natural Gas

Effect of Cuo Addition on the Performance of V2o5-Based Oxygen Carriers for Chemical-Looping Oxidation of H2s for Efficient Sulfur Recovery from Natural Gas

The incorporation of Cu into the clinker phases.

The effect of CuO addition on the phase composition of clinker and the Cu incorporation into the structure of clinker phases was monitored under laboratory conditions. Separate synthesized CuO-doped clinker phases as well as clinkers with different CuO content up to 4 wt.% were characterized by XRD, optical and electron microscopy with EDS analysis. It has been found that Cu tends to form a separate phase or a double oxide with Ca and incorporates in the clinker phases to a limited extent, except for C4 AF. With increasing CuO content in clinker, its phase composition changes, and the size of alite crystals increases.

Multi‐technical study of copper oxide on graphitic carbon nitride and its role in the photocatalytic reactions

AbstractBased on a facile three‐step preparation method, CuO/g‐C3N4 photocatalysts have been successfully synthesized by exfoliation of a bulk graphitic carbon nitride and subsequent hydrothermal decoration with CuO nanoparticles. Several advanced scientific tools were used to characterize crucial features of the prepared materials, in particular, to understand the role of copper oxide in photocatalytic reactions. CuO/g‐C3N4 reached a remarkably increased light‐induced photocatalytic reduction of water to hydrogen as well as oxidation of formaldehyde to CO2, in comparison with a neat g‐C3N4. The presence of CuO co‐catalyst resulted in more than 10 times higher H2 production rate. The increase of photocatalytic efficiency was observed also in the case of HCHO oxidation, but the effect of CuO addition was less impressive. Moreover, it has been evidenced that the durability of photocatalyst raised with an increasing amount of copper oxide. Simultaneously, the copper modified composites exhibited an improved photoelectrocatalytic (PEC) performance, confirmed by the photocurrent density measurements. In the following paper we described our findings concerning the role of copper oxide in CuO/g‐C3N4 composites.

Effects of CuO addition on the sinterability and electric properties in PbNb2O6-based ceramics

PbNb2O6 (PN)-based ceramics with tungsten bronze structure are promising piezoelectric materials in high-temperature devices such as piezoelectric vibration transducers. However, the PN-based ceramics usually exhibit a low bulk density, which greatly limits their practical applications. In this work, CuO was used as the sintering aid to form a liquid-phase bridge, leading to an obvious increase of the bulk density of PN-based ceramics by 11% (from 5.25 to 5.85 g cm−3) and the improvement of the piezoelectric constant (d33) (from 168 to 190 pC/N) and the Curie temperature (TC) from 367 to 395 °C. The positive influence of CuO on densification has been proved by SEM and fracture toughness. The XRD patterns confirmed that there was no secondary phase introduced by CuO addition. The Raman spectra revealed that part of Cu2+ ions has probably diffused into host lattice of the PN and preferred to occupy on A-sites. These results not only demonstrate the high potential of the CuO added PN-based ceramics for high-temperature piezoelectric applications, but also reveal the corresponding structure-properties relationship as well as provide a way to improve the sinterability, d33, and TC simultaneously.

The effects of CuO additives as the dendrite suppression and anti-corrosion of the Zn anode in Zn-air batteries

The new copper oxide-zinc composites (CuO–Zn) can be used to relieve the dendrite formation, corrosion reaction, and increase the reversibility of Zn anode. CuO–Zn composites were produced by mixing Zn and additive powders to prevent dendrites and the Zn corrosion and can be easily manufactured technically by simply adding it. To confirm the dendrite suppression, an electrodeposition method was conducted. Surface of Zn anode was analyzed by FE-SEM images and CuO showed a more controlled dendrite morphology than other Cu compounds. After the CuO–Zn electrodes were produced using 0.1, 0.5, 1.0, and 3.0wt.% CuO in Zn, an H2 gas evolution test was adapted to examine the anti-corrosion. The 0.5wt.% CuO electrode exhibited the lowest H2 gas evolution. To assess the improved performances, several electrochemical measurements like cathodic overpotential, tafel polarization, cyclic voltammetry, and DC-cycling test (full cell test) were conducted and the 0.5wt.% CuO mixed Zn electrode showed the best reversibility of all samples and longer cycle life until 19 cycles than 13 cycles of pristine Zn.

The Effect of CuO on the Thermal Behavior of the High-Energy Combustion Agent of the Al/MnO2 System

In this work, the effect of CuO addition into the high-energy combustion agent of Al/MnO2 system was studied. First, the combustion experiments of five samples with different contents had been carried out, in which CuO was found capable of influencing the flame ejection to a great extent. Then, in order to find out the underlying reasons, CuO effects on the thermal behavior of Al/MnO2 system were analyzed via theoretical calculations of Gibbs free energy and enthalpy changes. In addition, field emission scanning electron microscopy (FE-SEM) that could characterize the mixture morphology and thermogravimetric-differential scanning calorimetry (TG-DSC) that could indentify the exothermic and endothermic reactions and measure mass change were carried out. Finally, on the basis of all experimental findings, it was suggested that addition of CuO into Al/MnO2 system could result in dramatic increase of gas content throughout the reaction and the consequent high pressure. Also, speed of flame injection and heat released in the high-temperature area would thus be conducive to the continuous exothermic behavior of the reaction.

Effect of CuO additives on the formation of SnO2-rich layers in Ag-SnO2 materials

In order to investigate the effect of CuO additives on the formation of SnO2-rich layer in Ag-SnO2 contact materials, the laser rapid melting experiment was carried out on Ag-SnO2 contact materials for the purpose of simulating the rapid melting process of an instantaneously arc melted surface layer during arc erosion. The microstructure of laser melted and arc eroded Ag-SnO2 materials were investigated using scanning electron microscopy (SEM). The experimental results were also theoretical analyzed with two models dealing with the particle-dendrite interaction during solidification process. It was found that the Ag-SnO2 materials with CuO additives have found no SnO2-rich layer in the re-melted area and the SnO2 particles still stayed in Ag matrix because of the increasement of dragging force between Ag matrix and SnO2 particle. As the dragging force increase, the advance speed of SnO2 particles in front of S/L interface was lowered and SnO2 particles were apt to be engulfed by Ag matrix during solidification, so the CuO doped SnO2 particles were more difficulty to be pushed out of the Ag matrix than pure SnO2 particles. These results indicated that the effect of CuO additives on the formation of SnO2-rich layer in Ag-SnO2 contact materials was enhanced the wettability of SnO2 particles in Ag melt pool and restrained the SnO2 particles rise to the contacts surface.

Studies on effect of CuO addition on mechanical properties and in vitro cytocompatibility in 1393 bioactive glass scaffold

Copper doped bioactive glasses have been reported as the potential biomaterial for diseased or damaged bone repair and act as stimulants to new bones formation. In the present manuscript, we have synthesized 1393 derived glass based scaffold with the general formula of (54.6 − X)SiO2·6Na2O·7.9 K2O·7.7 MgO·22 CaO·1.74 P2O5·XCuO (all are in mole%; where X = 0,1,2,3) through traditional melt-quench route and the samples were designated as 1393, 1393-1Cu, 1393-2Cu and 1393-3Cu respectively. Polymer foam with interconnected pores has been used on later stage to prepare porous (porosity > 50%) bioactive scaffolds. The addition of CuO in glass scaffolds was to ensure its cytocompatibility, ability to enhance cell proliferation and improvements in mechanical properties. Increasing trend of CuO in the 1393 glass scaffold has resulted in increasing compressive and flexural strength and elastic modulus of the scaffolds.In-vitro cellular growth inhibition and cell viability assay of CuO incorporated 1393 glass scaffolds demonstrated that it did not inhibit proliferation and viability of human squamous carcinoma cell (SCC-25) at low materials concentration. The materials caused moderate level of apoptosis at higher concentrations and were also tolerated by human RBC as studied by hemolytic assay. The results indicated that CuO incorporated 1393 scaffolds could be a potential biomaterial for neobone tissue engineering application.

Effect of CuO-addition on the Dielectric Parameters of Sodium Zinc Phosphate Glasses

The dielectric properties of sodium zinc phosphate glasses doped with copper oxide have been investigated over a frequency range of 1.05–100 kHz in a vacuum medium (10−5 torr). Some dielectric parameters, such as dielectric constant e′, dielectric loss e′′, dielectric loss tangent (tan δ) and AC conductivity, have been estimated. It is observed that the dielectric constant is strongly dependent on the CuO concentration in the investigated phosphate glasses. The AC conductivity measurements show that these phosphate glasses are good electronic conductors. With the aid of transmission spectra of these glasses, the absorption coefficient and the optical direct bandgap are estimated. The optical bandgap is found to decrease with increasing CuO content indicating the formation of non-bridging oxygens.

Effect of CuO Addition on Thermal Properties of Diopside-Based Glass-Ceramics for LED Packaging

Effect of CuO Addition on Thermal Properties of Diopside-Based Glass-Ceramics for LED Packaging

Optimized sintering properties and temperature stability of MgZrTa2O8 ceramics with CuO addition for microwave application

Microwave dielectric ceramics CuO–modified MgZrTa2O8 were synthesized by the conventional solid-state reaction method. The effects of CuO additives on the sintering characteristics and microwave dielectric properties have been investigated. With CuO addition, the sintering temperature of MgZrTa2O8 ceramics can be effectively lowered from 1475 to 1375 °C without decreasing its dielectric properties obviously and the temperature coefficient of the resonant frequency of MgZrTa2O8 ceramics have been optimized to near-zero. The crystalline phase exhibited a wolframite crystal structure and no second phase was detected at low addition levels. The grain growth of CuO–modified MgZrTa2O8 ceramics was accelerated due to liquid phase effect. The relative dielectric constants (er) were correlated with apparent density and were not significantly different for all levels of CuO concentration. The quality factors (Q × ƒ) and temperature coefficient of resonant frequency (τƒ), which were strongly dependent on the CuO concentration, were analyzed by the grain size and the dielectric constant respectively. A best Q × ƒ value of 116400 GHz and τƒ value of −6.19 ppm/℃ were obtained for specimen with 0.05 wt% CuO addition at 1375 °C.

Effect of CuO addition on crystallization and thermal expansion properties of Li2O–ZnO–SiO2 glass-ceramics

A Li2O-ZnO-SiO2 (LZS) glass system was modified with CuO, and its phase development, microstructure evolution, crystallization kinetics and thermal expansion properties were investigated as a function of heat treatment temperature. As a result of the X-ray diffraction study and microstructure observation, lithium zinc silicate formed as the first crystalline phase with increasing heat treatment temperature. Silica polymorph developed as minor crystalline phase at higher temperatures. From the X-ray diffraction patterns, CuO addition led to a decrease in both the crystallization temperature of lithium zinc silicate phase and the volume fraction of quartz phase. According to the crystallization kinetics, the crystallization activation energy for lithium zinc silicates is almost equal to the diffusion activation energy of Zn2+ in glass, it suggests that the diffusion of network modifier Zn2+ dominates the crystallization of lithium zinc silicates. Additionally, CuO addition caused the transition of Zn2+ from network modifiers to network formers. From the thermal expansion coefficient measurements, two abrupt changes in slope of the thermal expansion curves were observed and attributed to the phase transitions of cristobalite and lithium zinc silicate, respectively. Comparison of the thermal expansion coefficient of two types of glass-ceramics revealed that CuO addition in the LZS system can partly inhibit the formation of cristobalite at high temperatures.

Effect of CuO on microstructure and conductivity of Y-doped BaCeO3

Effect of CuO additions on sinterability and conductivity of BaCe0·85Y0.15O2.925 was studied. Two different amounts, 0.75 and 1.5wt% with respect to the pure powder, were considered. Microstructural characterization showed that for smaller additions Cu was completely incorporated on B-site of the perovskite, while formation of the secondary phase Y2BaCuO5 was detected when higher amount of CuO was added. Enhanced cations diffusivity at grain boundary is responsible for a pronounced reduction of sintering temperature and grain growth. Density as high as 96–97% of theoretical value was obtained when sintering at 1000°C for 2h.As long as Cu is incorporated in the perovskite, higher conductivity and lower activation energy of grain core were found. In addition, total conductivity of 0.75wt% doped material was limited by fine grain size that resulted in apparent poor conductivity of the grain boundary.On the contrary when Cu segregates in the Y2BaCuO5 phase, overall conductivity increased mostly because of the contribution from the electronic conductivity of that phase.

Photocatalytic oxidation and simultaneous removal of arsenite with CuO/ZnO photocatalyst

Abstract We investigated the photocatalytic oxidation and simultaneous removal of arsenite in synthetic aqueous As solution with high concentration. The process was performed by using CuO/ZnO nanoparticles under UV irradiation at around neutral pH. The effects of CuO addition, initial arsenite concentration and photocatalyst loading on the treatment efficiency were investigated. Adsorption of arsenic onto catalytic surface was evaluated with fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Batch results showed it that CuO has a significant effect on the photocatalytic performance of ZnO. The rate constant of photocatalytic oxidation with CuO(20%)/ZnO was 4 times better than those obtained with pristine ZnO. The removal amount (mg g −1 ) of arsenic increased with an increase in initial arsenic concentration. As(III) solution of 30 mg L −1 could be completely removed with photocatalyst of 0.67 g L −1 during 10 h of irradiation time. The maximum As(III) removal amount by photocatalytic oxidation and simultaneous removal was 6.5 times larger relative to that observed in the adsorption in dark. The excellent photocatalytic oxidation and high uptake performances make CuO/ZnO a potentially attractive candidate for the removal of As(III) from highly arsenic contaminated water.

저온소결 (Na,K,Li)(Nb,Sb,Ta)O3계 세라믹스의 미세구조 및 압전특성

In this paper, piezoelectric ceramics with the composition of (Na0.525K0.4425Li0.0375)(Nb0.8975Sb0.065Ta0.0375)O3 + 0.3 wt% CoO + x CuO (0.005≤x≤0.025) (abbreviated to NKL-NST) were fabricated for ultrasonic sensor application. The effects of CuO addition and sintering on the microstructure and the piezoelectric properties of the NKL-NST ceramics were systematically studied. Excellent piezoelectric properties such as electromchanical coupling factor(kp) = 0.415, piezoelectric constant (d33) =166 pC/N and piezoelectric figure of merit d33*g33= 5.47 pm/N were obtained from the 2.5 mol% CuO doped NKL-NST+0.3 wt%CoO ceramics sintered at 1,000°C for 3 h.

Effects of CuO additives and sol–gel technique on NiNb2O6 dielectric ceramics for LTCC application

The effects of CuO additives and sol–gel method synthesis on the sintering behavior, microstructure and the microwave dielectric properties of NiNb2O6 ceramics were investigated systematically. The NiNb2O6 ceramics were synthesized with traditional solid state method and sol–gel method, and the CuO additives were used in the solid state method for comparison. The sintering temperature of NiNb2O6 ceramics with the highest densification can be effectively reduced from about 1275 °C to 1050 and 1100 °C respectively by using CuO additions and sol–gel technique. To study their applicability in low temperature co-fired ceramic technology, dielectric properties have been characterized. The dielectric properties exhibited a significant dependence on the sintering condition, composition and crystal structure of the ceramics. In particular, the 2.5 wt% CuO-doped NiNb2O6 ceramics sintered at 1050 °C have excellent microwave dielectric properties: er = 21.45, Q × f = 23,531 GHz, τf = −27.9 ppm/°C. While the NiNb2O6 ceramics prepared by sol–gel method obtain microwave dielectric properties as: er = 19.16, Q × f = 11,149 GHz, τf = −27.3 ppm/°C after sintered at 1100 °C for 2 h.