Increasing CuO Content Research Articles

Gamma Ray Irradiation Effects on the Mechanical and Chemical Properties of CuO–Bi<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> Glasses

The effect of gamma radiation on the mechanical and chemical properties of x CuO, (70-x) Bi₂O</sub>3<sub>, 20SiO₂,10 Na₂O, where 0 ≤ x ≤ 30 weight % were carefully studied in order to obtain information about the changes that appear in the structure of the glass matrix with the doping of copper ions. The glass matrix was fabricated by melt-quenching technique. The results showed that, the glass system has good durability, density and mechanical properties with increasing CuO content at the expense of Bi₂O₃, and that the effect of irradiation with gamma dose is very small. UV-VIS absorption spectra for all glasses have a single asymmetric band, which corresponds to a BiO₃→BiO₆ transition of the Cu²⁺ ions in octahedral symmetry with an elongated tetragonal distortion. These measurements indicate the presence of Cu²⁺ ions in the glasses. Furthermore, it has good water resistance ability with increasing copper oxide. So, it can be used as a container for keeping radioactive waste and radioactive sources.

Dielectric and optical properties of CuO containing sodium zinc phosphate glasses

Dielectric and optical properties of 45 P2O5-34 ZnO-(20?x)Na2O-1 Al2O3-xCuO glasses (0?x?5) were investigated. The frequency and composition dependencies of the dielectric parameters were analysed and discussed. The values of real part of dielectric constant (RPDC) lie between 748 to 1169 for RPDCMax, and 654 to 1031 for RPDCMin. The range of values of imaginary part of dielectric constant (IPDC) extends from 39.4 to 57.5 for IPDCMax and from 27.3 to 40.1 for IPDCMin. It was observed that each of these parameters begins to decrease with increasing CuO content, but further addition of CuO causes their rise. Thus, small amount of CuO causes a decrease in both RPDC and IPDC until CuO content reaches 2mol%, thereafter, they nearly return to their original values at 5mol% of CuO. Similar behaviour was observed for AC conductivity. Transmittances of the investigated glasses were also measured and used to estimate their optical absorption coefficients and optical band gaps. The optical energy gap is ~4 eV for the samples with up to 4mol% CuO, while it is somewhat higher (~5 eV) for the glass with 5mol% CuO.

Structural and optical properties of CuO in zinc phosphate glasses and effects of gamma irradiation

Collective optical and infrared measurements have been employed to investigate the state of increasing copper ions in host 0.5ZnO–0.5P2O5 glass composition. The same spectral measurements were repeated after gamma irradiation with a dose of 20 and 80 KGy. Optical absorption spectra reveal strong UV absorption due to trace ferric ions present as unavoidable impurities within the chemicals used in the preparation of the glasses. Copper containing glasses show an additional broad visible-near infrared band due to distorted octahedrally coordinated Cu2+ ions which at high CuO contents exhibit splitting to several component absorption peaks. Gamma irradiation causes several variations between the response of the base host zinc phosphate glass and effect of increasing CuO. These changes are correlated with both the formation of induced defects through suggested photochemical reactions in the UV region and some shielding effects with increasing CuO in the visible-near infrared spectrum. Infrared absorption spectra reveal repetitive vibrational bands due to phosphate groups mainly from metaphosphate units and the spectra show some variations with the increase of CuO content visualize by the increase of the intensity of the mid broad band extending in the range 800–1500 cm−1.

Electric transport property and temperature stability of magnetoresistance in La0.6Dy0.1Sr0.3MnO3/x(CuO)

The samples of La0.6Dy0.1Sr0.3MnO3/x(CuO)(x=0.00, 0.08, 0.12, 0.16, 0.20) were prepared by the solid-state reaction method. Electric transport property and temperature stability of magnetoresistance of the samples were studied through X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) photograph, resistivity–temperature (ρ–T) curves in zero field and in applied magnetic field, and magnetoresistance–temperature (MR–T) curves. With the increase of CuO content, resistivity increases, and ρ–T curves exhibit a peak near 320K, which is induced by double exchange. In the meantime, ρ–T curves exhibit a “shoulder peak” in the temperature range of 250–220K, which is induced by boundary effect. MR–T curves exhibit a sharp peak at high temperature, MR increases continuously with temperature decreasing in low temperature range, and MR exhibits a platform in the intermediate temperature range, then the temperature stability of magnetoresistance appears. For the sample with x=0.16, magnetoresistance keeps at 9.0±0.2% without change in the temperature range of 222–272K in the magnetic field of 0.8T. The intrinsic magnetoresistance and extrinsic magnetoresistance of samples have been discussed, and the mechanism of temperature stability of magnetoresistance is provided.

Effect of copper oxide on structure and physical properties of lithium lead borate glasses

Copper-doped Lead lithium borate glass samples with the composition of (35-x) Pb3O4–xCuO–65Li2B4O7, where x = 5, 10, 15 or 20 mol%, have been prepared by melt quenching technique. Glass-forming ability, density, electrical conductivity, magnetic susceptibility and structural properties of lead lithium borate glasses have been investigated. IR spectroscopic data show that the copper ions play the role of glass modifier. Addition of CuO influences BO3 ↔ BO4 conversion. Density is expressed in terms of the structural modifications that take place in glass matrix. The increase in Tg reflects an increase in bond strength, and samples obtain more rigid glass structure. Electrical conductivity and magnetic susceptibility χ data show a variable behavior with the increase in the copper content in two valance states Cu+ and Cu+2. In addition, optical properties depend on the change of the role of copper ions in the samples’ structure. Optical energy band gap E opt and Urbach energy E tail are determined. The increase in E opt and UV cutoff with an increase in CuO content is due to the decrease in non-bridging oxygen concentration. The decrease in E tail at higher concentrations is attributed to the copper ion accumulation in the interstitial positions and to the formation of orthoborate groups. These samples are suitable for the green light longpass filters.

Reducing the optical band gap of polyvinyl alcohol (PVA) based nanocomposite

Optical properties of pure polyvinyl alcohol (PVA) and PVA based nanocomposite films have been investigated. The nano-composite samples were prepared by the well known solution cast method. The experimental results shows that the absorption and absorption coefficient parameters are greatly affected by variation of copper oxide (CuO) nanoparticles concentration. The absorption versus wavelength for the doped samples is exponential while the absorbance of pure PVA is sharply varied with wavelength. An obvious surface plasmonic resonance peaks for the nano-composite samples were appeared. The absorption edge was greatly shifted to lower energy for the PVA doped samples. It was observed that optical band gap of pure PVA is significantly reduced upon the addition of CuO nanoparticles. The increase of refractive index with increasing CuO concentration is an evidence for the formation of new energy states and thus decreasing the energy band gap of PVA. The increase of optical dielectric constant was observed upon the addition of CuO nanoparticles. The optical dielectric loss peaks are shifted to higher wavelength with increasing the CuO concentration. The optical conductivity is increased upon the addition of CuO nanoparticles. The dispersion region in the refractive index spectra are well obeyed the single oscillator of the Wemple–Didomenico model for all the samples.

UV Emission of Gd³⁺ in the Presence of Cu²⁺ : Towards Luminescence Quenching through Quantum Cutting?

The first investigation into the ultraviolet (UV) photoluminescence of gadolinium(III) in the presence of copper(II) is reported. A melt-quenched barium phosphate glass was used as a model matrix. The optical spectroscopy assessment shows that with increasing CuO concentration the Cu(2+) absorption band grows steadily, whereas the UV emission from Gd(3+) ions is progressively quenched. The data, thus, suggests the existence of a Gd(3+) →Cu(2+) energy-transfer process ocurring through quantum cutting. A downconversion/cross-relaxation pathway proceeding through a virtual state in Gd(3+) is proposed. These findings suggest gadolinium(III) could potentially be used in the optical sensing of copper(II).

High piezoelectricity in low-temperature sintering potassium–sodium niobate-based lead-free ceramics

Here we have realized three goals in a new potassium–sodium niobate material using CuO as sintering aid, such as low temperature sintering, the suppression in the loss of alkali metals, and attaining a high d33. Low-temperature sintered 0.96(K0.46Na0.54)Nb0.95Sb0.05O3–0.04Bi0.5(Na0.82K0.18)0.5ZrO3 ceramics were made conducting by adding CuO using an ordinary ceramic fabrication technique. The sintering temperatures drop from 1095 °C to 950 °C when the CuO content is increased from 0 to 2.5 wt%, and the K and Na loss could be also prevented under a low processing temperature. In addition, the ceramics undergo a phase transition with increasing CuO content, such as from a rhombohedral–tetragonal phase coexistence to the mixture of both rhombohedral–orthorhombic and orthorhombic–tetragonal phase boundaries. The inhomogeneous Cu2+ distributions become more obvious as the CuO content rises, i.e., the excess Cu2+ aggregates at the small grains region for a low CuO content (x ≤ 1.5), and at the small and large grains zones for x = 2.5. The dielectric constant gradually decreases as the CuO increases, and the dielectric loss is lowered by adding CuO content. A well polarization vs. electric field (P–E) loop is seen in the ceramics with x ≤ 2.5, and those with x = 2.5 possess a high d33 of 310 pC N−1 even if the sintering temperatures drop down to 950 °C. As a result, it is an efficient way to promote the piezoelectricity of copper oxide-modified alkaline niobate ceramics using a low-temperature sintering technique.

Optical properties of lithium lead borate glass containing copper oxide for color filter and absorption glass

Lithium lead borate glass samples containing copper oxide are prepared using the normal melt-quenching technique. The optical constants are investigated and discussed with the substitution of $$\hbox {Pb}_{3}\hbox {O}_{4}$$ for CuO. The UV/VIS/NIR absorption spectra have been recorded at room temperature. The optical energy band gap $$\hbox {E}_{\mathrm{opt}}$$ and Urbach energy $$\hbox {E}_{\mathrm{tail}}$$ was determined. The increase of $$\hbox {E}_{\mathrm{opt}}$$ and UV cut off are due to the decrease of nonbridging oxygen concentration with increase of CuO content. The decrease of $$\hbox {E}_{\mathrm{tail}}$$ at higher concentrations is attributed to the copper ion accumulation in the interstitial positions and to the formation of orthoborate groups. Refractive index (measured and calculated), molar refraction and polarizability are correlated with the composition of the glasses. And produce a longpass filters with cutoffs in the range of 190–400 nm.

Characterization of aqueous interactions of copper-doped phosphate-based glasses by vapour sorption

Owing to their adjustable dissolution properties, phosphate-based glasses (PGs) are promising materials for the controlled release of bioinorganics, such as copper ions. This study describes a vapour sorption method that allowed for the investigation of the kinetics and mechanisms of aqueous interactions of PGs of the formulation 50P2O5–30CaO–(20–x)Na2O–xCuO (x=0, 1, 5 and 10mol.%). Initial characterization was performed using 31P magic angle spinning nuclear magnetic resonance and attenuated total reflectance–Fourier transform infrared spectroscopy. Increasing CuO content resulted in chemical shifts of the predominant Q2 NMR peak and of the (POP)as and (PO−) Fourier transform infrared absorptions, owing to the higher strength of the POCu bond compared to PONa. Vapour sorption and desorption were gravimetrically measured in PG powders exposed to variable relative humidity (RH). Sorption was negligible below 70% RH and increased exponentially with RH from 70 to 90%, where it exhibited a negative correlation with CuO content. Vapour sorption in 0% and 1% CuO glasses resulted in phosphate chain hydration and hydrolysis, as evidenced by protonated Q0(1H) and Q1(1H) species. Dissolution rates in deionized water showed a linear correlation (R2>0.99) with vapour sorption. Furthermore, cation release rates could be predicted based on dissolution rates and PG composition. The release of orthophosphate and short polyphosphate species corroborates the action of hydrolysis and was correlated with pH changes. In conclusion, the agreement between vapour sorption and routine characterization techniques in water demonstrates the potential of this method for the study of PG aqueous reactions.

Copper-containing mesoporous bioactive glass coatings on orbital implants for improving drug delivery capacity and antibacterial activity

Anophthalmic orbit restoration with artificial implants is usually accompanied with the risks of bacterial penetration and implant exposure. Here, we develop a facile evaporation-inducing self-assembly approach to modify the porous hydroxyapatite (pHA) orbital implants by using sol-gel derived CuO-containing mesoporous bioactive glass (Cu-MBG). The Cu-MBG coatings with 0-5 mol% CuO were prepared in the pore wall of pHA by immersion-evaporation-ageing route in the sol precursor of Cu-MBG. Brunauer-Emmett-Teller and Barrette-Joyner-Halenda analyses showed that the specific surface area and pore volume were slightly decreased with increasing CuO content, while the Cu-MBG-modified pHA maintained a sustained release of ofloxacin and significantly inhibited the bacterial viability (Staphylococcus aureus and Escherichia coli). These studies demonstrate that the Cu-MBG modification provides an effective and facile strategy to endow combined biological performances of pHA orbital implants and potentially reduce implant-related side effects.

Preparation of Nanoporous Pd/CuO by Dealloying and Their Electrocatalysis for Methanol in Alkaline Condition

A novel and simple approach for fabrication of nanoporous Pd/CuO catalysts is reported. The nanoporous Pd/CuO catalysts were successfully prepared by chemical dealloying Ti-Cu-Pd amorphous alloy in a 1.25 M HCl solution. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) tests homogeneous nanoporous structures are formed. The Pd: CuO ratio of the catalysts could be controled by adjusting the original composition of the alloy. Cyclic voltammetry (CV) and chronoamperometry (CA) were used to measure the electrocatalytic activities of the Pd/CuO catalysts. It was found that the catalytic activity was improved firstly and then depressed by increasing Pd content within both EASA and methanol electro-oxidation region. The catalyst prepared by Ti30Cu60Pd10 ribbon showed the best catalytic activity due to appropriate Pd: CuO ratio. The peak current densities in the CV curves were increased with the increase of the methanol concentration, and the catalysts maintained good electrocatalytic activities in the solution with high methanol concentration (4 M). In addition, the charge transfer resistance tested by electrochemical impedance spectroscopy (EIS) decreases with the increase of CuO content, this indicates Pd : CuO ratio plays very important role in the electro-catalytic process and confirms the bifuntional mechanism of CuO.

Enhancement in dielectric, ferroelectric, and electrostrictive properties of Pb(Mg1/3Nb2/3)0.9Ti0.1O3 ceramics by CuO addition

Effects of CuO on dielectric, ferroelectric and electrostrictive properties of Pb(Mg1/3Nb2/3)0.9Ti0.1O3(PMNT) ceramics were studied. The PMNT/xCuO (with x=0, 0.2, 0.4, 2.0 and 4.0mol.%) ceramics were prepared by using solid state reaction and sintering process. It was found that the pseudo-cubic lattice parameter, a, gradually increased while the angle α decreased with increasing CuO content. Maximum dielectric constant showed a decreasing trend with increasing CuO with an abrupt increase in value at x=2.0mol.%. The temperature of maximum dielectric constant and depolarization temperature tended to increase while the diffuseness of dielectric peak decreased with increasing CuO concentration. Remanent polarization and coercive field of pure PMNT sample were ∼1.8μC/cm2 and 0.6kV/cm, respectively, which were increased to ∼3.5μC/cm2 and 1.8kV/cm when x=0.2mol.%. With x>0.2mol.%, coercive field gradually decreased with increasing CuO content while remanent polarization did not significantly change. With x⩽2.0mol.%, induced strain and electrostrictive coefficient tended to increase with increasing CuO content, with maximum values of 0.09% (at 10kV/cm) and 19.90×10−16m2/V2, respectively, for the PMNT/2.0mol.% CuO sample. An enhancement in polar order of PMNT ceramics due to an addition of CuO was observed.

Copper ions influence on lead–phosphate glass network

The structure of xCuO·(1−x)[2P2O5·PbO] glass system with 0⩽x⩽50mol% was investigated by Raman spectroscopy. The characteristic bands of these glasses were identified and analyzed by increasing CuO content. A deconvolution of each Raman spectrum was made in order to make a better identification and assignment of all bands which appear in these spectra Thus, by determining the number of all independent components it was possible to carry out a quantitative analysis of the spectra and also to find the concentration distribution of these components across the investigated glass system. By adding CuO, the symmetric vibration of POP bond in Q2 groups shifts to higher frequencies due to the depolymerization of long phosphate chains and the bands attributed to (PO2)asym. stretching and (PO)sym. stretching vibrations shift to lower frequencies due to the linking of PO bond to cooper ions. The UV–visible optical absorption results suggest that Cu ions act as a modifier in the studied glasses and may have a possible former role over 20mol%. Beside this, cooper can be considered as a color center in this glass system.

Gamma rays interaction with copper doped lithium phosphate glasses

Undoped and copper-doped lithium phosphate glasses were prepared. CuO-doped glasses possess characteristic greenish color which deepens with the increase of CuO content. Experimental optical absorption spectra of the undoped lithium phosphate glasses reveal strong ultraviolet absorption bands and no visible bands are observed. These strong UV bands are assumed to originate from unavoidable trace iron ions contamination within the chemicals used for the preparation of the glass. The optical absorption spectra of the CuO-doped phosphate glasses reveal the same UV absorption as observed in the undoped samples beside an extra broad visible absorption band which splits to some component peaks. Such visible spectra are related to the presence of divalent copper (Cu2+) ions in distorted octahedral coordination. Gamma irradiation of the undoped sample produces induced defects generated through the liberation of pairs of electrons and positive holes. CuO-doped glasses show some shielding behavior towards successive gamma irradiation especially at high CuO contents. FTIR absorption spectra of the studied glasses indicate the appearance of characteristic vibrational bands due to phosphate groups. Gamma irradiation causes minor effects on the FTIR spectra, but the bands due to water molecules are strongly affected by gamma irradiation because of loose bonding within the glass network.

Parameters of TSMG Process for Y1.5Ba2Cu3O x System with CeO2 Addition

The TSMG process of YBCO bulk superconductors with Y1.5Ba2Cu3Ox composition and 1 wt% CeO2 addition has been studied. It is shown that the window for isothermal growth of single-crystalline sample grown from Sm123 seed is between 988 ∘C and 1003 ∘C. At lower temperatures of this window, Y123 crystals grow with higher growth rate but the quality of crystals is worse due to the formation of steps at the growth front. During an isothermal dwell at the optimized temperature, the growth of Y123 single-crystal stops due to decreasing peritectic temperature with increasing CuO concentration in the melt. Additional slow cooling 1 ∘C/hour from the temperature of isothermal growth leads to epitaxial growth of Y123 crystal over the entire sample. Only very narrow part at the rim of the sample contains CuO phase and blocky Y123 crystals are formed there due to self-nucleation.

Effects of CuO nanoparticles addition on properties of PMNT ceramics

This research investigates the role of CuO nanoparticles addition on properties of 0.9PMN–0.1PT (PMNT) ceramics. Phase purity, density, microstructure, dielectric and ferroelectric properties of the ceramics were investigated. The density of the ceramics reaches a maximum when 0.5wt% of CuO is added into the ceramics while grain size of the ceramics tends to increase with the increase in CuO content. εmax of the ceramics tends to increase with increasing CuO concentration. The improvement of Pr of the ceramics is observed in the ceramic incorporated with over 0.1wt% of CuO.

Influence of Y2O3 and CeO2 additions on growth of YBCO bulk superconductors

The Top-Seeded Melt-Growth process for preparation of bulk YBCO single-grain samples from the nominal composition 1mol YBa2Cu3Ox, 0.25mol Y2O3 and 1wt% CeO2 was analysed by optical and electron microscopy, EDAX microanalyses and thermal analyses. It is shown that 4.2wt% of CuO is formed after reaction of constituents. During an isothermal dwell at the optimised temperature, the growth of Y123 single-crystal stops due to decreasing peritectic temperature with increasing CuO concentration in the melt. The growth at furnace cooling leads to trapping of droplets of melt into the growing crystal, which finally epitaxially crystallises on Y123 as BaCu2O2 phase. The last part of the sample solidifies as Y123 elongated spheroids with Y211, BaCu2O2 and CuO phases. Additional slow cooling 1°C/h from the temperature of isothermal growth leads to epitaxial growth of Y123 crystal over the entire sample. Only very narrow part at the rim of the sample contains CuO phase and blocky Y123 crystals are formed there due to self-nucleation.

Effects of V2O5 doping on the structure and properties lead-free KNN–LS–BF piezoelectric ceramics

(0.95Na0.5K0.5NbO3-0.05LiSbO3)-x mol% CuO (KNN-LS-xCuO) lead-free piezoelectric ceramics have been fabricated by a conventional solid-state reaction route at a lower sintering temperature and the effects of CuO-dopant on structure and properties of KNN-LS ceramics have been studied. It is found that the addition of CuO significantly improves the sinterability and properties of KNN-LS ceramics. X-ray diffraction data shows that a small amount of CuO does not change the phase structure of KNN-LS and a dense microstructure with smaller and more uniform grains is developed, probably due to liquid-phase sintering. With the increase of CuO content x, the relative density, d 33 , k p , tanδ and Q m have been improved obviously when x < 0.45 due to the presence of the liquid phase and the refined grains, but excessive CuO would degrade the comprehensive properties of KNN-LS-xCuO ceramics. The best specimen with a high relative density of 98.53 % was fabricated when x = 0.45 at 1,060 °C, relating constants respectively are: d 33 = 175pC/N, k p = 0.46, e r = 551.23, tanδ = 1.41 %, Q m = 41.5.

Thermal, structure and morphological properties of lithium disilicate glasses doped with copper oxide and their glass–ceramic derivatives

This research aims to investigate and compare the structural and the morphological properties of both lithium disilicate glasses doped with copper oxide and their glass–ceramic derivatives. Density measurements were measured for all samples by Archimedes method at room temperature. Differential scanning calorimetric analysis was used to determine the glass transition temperature (Tg) and crystallization temperature (Tc) for all glasses. The glass transition temperature was observed to decrease with increasing CuO concentration indicating the formation of non-bridging oxygen bonds in the glass network. X-ray analysis patterns reveal the appearance of crystalline lithium metasilicate phase as the main phase within the glass–ceramic derivatives, and their crystallite sizes were observed to decrease as the CuO increased. Experimental infrared absorption data indicate the existence of characteristic vibrational bands due to structural building SiO4 units in resemblance to the same vibrations observed from traditional crystalline silicates. Scanning electron microscopic investigations show the vitreous nature for lithium disilicate glasses and the distinct crystalline morphological features for the corresponding glass–ceramic derivatives.