Effect Of CuO Addition Research Articles

Synthesis and characterization of CuO/ZnO-doped (Zr0.8Sn0.2)TiO4 microwave ceramics

The (Zr0.8Sn0.2)TiO4 material (ZST), has been prepared by solid state reaction and characterized. The samples were sintered in the temperature range of 1050–1300 °C for 2 h. The effects of sintering parameters like sintering temperature and CuO addition (1–3 wt. %) on structural and dielectric properties were investigated. Bulk density increases from 4.4 to 5.2 g/cm3 with the increase of sintering temperature and adding elements. The effect of CuO addition is to lower the sintering temperature in order to obtain well sintered samples with high value of bulk density. The material exhibits a dielectric constant of 38.2 and high values of the Q.f product, greater than 60000, at microwave frequencies. The dielectric properties make the ZST material very attractive for microwave applications such as dielectric resonators, filters, dielectric antennas, substrates for hybrid microwave integrated circuits, etc.

Effect of CuO addition on electrochemical properties of AB 3-type alloy electrodes for nickel/metal hydride batteries

In order to improve overall electrochemical properties of AB 3-type hydrogen storage alloy electrodes, especially the cycling stability, CuO was added to the electrode. Electrochemical properties of the electrodes with and without additives were studied. Cyclic voltammetry and SEM results show that CuO is reduced to Cu during the charging process and the fine Cu particles deposit at surface of the alloy particles. The as-deposited Cu particles form a protective layer to increase electronic and heat conductivity of the electrodes and thus improve maximum discharge capacity, high rate dischargeability, cycling stability and dischargeability at high temperature of the electrodes. The maximum discharge capacity increases from 314 mAh g −1 (blank electrode) to 341 mAh g −1 (3.0 wt.% CuO) and the capacity retention rate at the 200th cycle increases from 71.6% to 77.2% (2.5 wt.% CuO).

Effect of CuO addition on sintering temperature and piezoelectric properties of 0.05Pb(Al0.5Nb0.5)O3−0.95Pb(Zr0.52Ti0.48)O3+0.7 wt.% Nb2O5 + 0.5 wt.% MnO2 ceramics

Effect of CuO addition on piezoelectric properties of 0.05Pb(Al0.5Nb0.5)O3−0.95Pb(Zr0.52Ti0.48)O3+0.7 wt.% Nb2O5 + 0.5 wt.% MnO2 (PAN-PZT) ceramics was studied to decrease the sintering temperature below 900°C for LTCC. The PAN-PZT ceramics sintered at 1200°C had piezoelectric properties of d33 = 340 pC/N, kp = 61.6%, Qm = 1,725, and density of 7.5 g/cm3. The addition of CuO significantly decreased the sintering temperature due to the formation of liquid phase containing a binary combination of PbO and CuO in grain boundary. Piezoelectric properties of d33 = 361 pC/N, kp = 57%, Qm = 145, and density of 7.8 g/cm3 were achieved at sintering temperature of 900°C. The CuO doped PAN-PZT ceramics show high density and d33 at low sintering temperature though its electromechanical quality factor abruptly decreases due to the CuO additive effect.

Effect of CuO additives on sintering and dielectric behaviors of CeO 2 ceramics

The effects of CuO addition (1 and 2 wt%) on microstructures and microwave dielectric properties of CeO 2 ceramics with CuO additions have been investigated. It is found that CeO 2 ceramics can be sintered at 1490 °C due to the liquid phase effect of CuO addition. At 1580 °C, CeO 2 ceramics with 1 wt% CuO addition possesses a dielectric constant ( ɛ r) of 21.7, a Q × f value of 50,000 (at 9GHz) and a temperature coefficient of resonant frequency ( τ f ) of −59 ppm/°C. A large sintering temperature reduction (about 200 °C) can be achieved by adding CuO to the CeO 2 ceramics. The CuO–added CeO 2 ceramics can find applications in microwave devices.

Effect of Small Amount CuO Doping on Microstructure and Properties of the Alkaline Niobate-Based Lead-Free Ceramics

Recently, it was reported that the alkaline niobate-based (K,Na,Li)(Nb,Ta,Sb)O3 (LF4) perovskite ceramics showed excellent piezoelectric properties and has been regarded as a new candidate of lead-free piezoelectric materials. However, the effects of additives on the piezoelectric property of LF4 have not been studied intensively so far. In this study, the effect of CuO addition to the LF4 was investigated. The sample showed a tetragonal phase at room temperature and also a second phase with low melt point. The Cu2 + can replace both A-site and B-site because of its radii. The mechanical quality factor (Q m ) increased from 26 to 137 as the CuO increased.

Effect of CuO Additives on Sintering and Microwave Dielectric Behaviors of 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 Ceramics

Microwave dielectric properties of the complex perovskite compound CuO-doped 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 ceramics have been investigated using the conventional solid state method. Copper oxide effectively lowers the sintering temperature of 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 ceramics as a sintering aid. Ordering of structures was not observed at sintering temperatures from 1240 to 1360°C. The dielectric constant (εr) saturated at a value of 38–40 from 1270 to 1360°C. The Q×f values of 15000–70000 (at 7 GHz) can be obtained in all cases when the sintering temperatures are in the range of 1240–1360°C. The temperature coefficient of the resonant frequency τf was independent of the sintering temperature. An εr value of 39.7, a Q×f value of 70000 (at 7 GHz), and a τf value of 17 ppm/°C were obtained for 1 wt % CuO-doped 0.95Ba(Zn1/3Nb2/3)O3–0.05BaZrO3 ceramics sintered at 1360°C for 2 h.

Microwave Dielectric Properties and Microstructures of CuO-Modified (1-x)(Mg0.95Co0.05)TiO3–xCaTiO3 Ceramic System

The effects of CuO additives on the microstructures and the microwave dielectric properties of (1-x)(Mg0.95Co0.05)TiO3–xCaTiO3 ceramics were investigated. The CuO additives can effectively reduce the sintering temperature of the ceramics to as low as 1175°C. With x = 0.08, at 1275°C, the 0.92(Mg0.95Co0.05)TiO3–0.08CaTiO3 ceramic possesses excellent microwave dielectric properties: a dielectric constant εr of 22.1, a Q×f value of 86400 GHz (at 7 GHz) and a τf value of 5.4 ppm/°C. Sintered ceramic samples were characterized by using X-ray diffraction pattern and SEM. Dielectric constants (εr) are not significantly affected by various additives and range from 20 to 23. By properly adjusting the x of (1-x)(Mg0.95Co0.05)TiO3–xCaTiO3 ceramics, small temperature coefficients (< ±3 ppm/°C) of resonant frequency (τf) are obtained for 0.93(Mg0.95Co0.05)TiO3–0.07CaTiO3 with 0.25 wt% CuO additives.

Characterization and dielectric behavior of CuO-doped ZnTa 2O 6 ceramics at microwave frequency

The effects of CuO addition on the microstructures and microwave dielectric properties of ZnTa 2O 6 ceramics were investigated. CuO was selected as a liquid-phase sintering aid to lower the sintering temperature of ZnTa 2O 6 ceramics. With CuO addition, the sintering temperature of ZnTa 2O 6 can be effectively reduced from 1350 to 1230 °C. The crystalline phase exhibited no phase difference and no second phase was detected at low addition levels (0.25–1 wt.%). The quality factors Q × f were strongly dependent upon the CuO concentration. A Q × f value of 65,500 GHz was obtained for specimen with 0.25 wt.% CuO addition at 1230 °C. For all levels of CuO concentration, the relative dielectric constants were not significantly different and ranged from 34.2 to 35.7. Tunable temperature coefficient of resonant frequency ( τ f ) can be adjusted to zero by appropriately turning the CuO content.

Effects of CuO addition on the structure and electrical properties of low temperature sintered Pb((Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80)O3 ceramics

Effects of CuO addition on the structure and electrical properties of low temperature sintered Pb((Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80)O3 ceramics

Effect of CuO on the properties of stannous chlorophosphate glasses

The effect of CuO addition on the properties of stannous chlorophosphate glasses has been studied. CuO addition improves the chemical durability of stannous chlorophosphate. Density, hardness, glass transition temperature and softening temperature increase, while thermal expansion coefficient and dissolution rate of the glasses decrease with increasing CuO content. The short-range structure of glasses was examined by X-ray photoelectron spectroscopy (XPS). O 1s and Cl 2p XPS spectra indicate that the relative amount of asymmetric bridging oxygen (P–O–Cu; P–O–Sn) increases, and that the concentration of non-bridging chlorine (P–Cl and Sn–Cl) decreases with increasing CuO content of the glasses. A structural model of Sn–(Cu)–P–O–Cl glasses is proposed to explain the property change due to composition variation.

Liquid Phase Sintering and Microwave Dielectric Properties of NdAlO3 Ceramics

The effects of CuO addition on the microstructures and microwave dielectric properties of NdAlO3 ceramics were investigated. CuO was selected as a liquid-phase-sintering aid to lower the sintering temperature of NdAlO3 ceramics. With CuO addition, the sintering temperature of NdAlO3 can be effectively reduced from 1650°C to 1410–1430°C. The crystalline phase exhibited no phase differences at a low addition level while Nd4Al2O9 and NdAl11O18 were presented as second phases at the addition level higher than 0.5 wt%. The quality factors Q×f were strongly dependent upon the CuO concentration. The Q×f value of 63000 GHz was obtained at 1410–1430°C with 0.25 wt% CuO. For all levels of CuO concentration, the relative dielectric constants were not significantly different and ranged from 21.5 to 22.6. The temperature coefficients varied from -30 ppm/°C to -45 ppm/°C. Results of X-ray diffraction analysis and scanning electron microscopy are also presented.

Structural Transition and Microwave Dielectric Properties of ZnNb2O6–TiO2 Sintered at Low Temperatures

The addition of CuO to ZnNb2O6–TiO2 significantly lowered the sintering temperature to ∼900°C in comparison to ∼1200°C for samples without CuO. The effect of CuO additions on the phase transitions and microwave dielectric properties of 0.42ZnNb2O6–0.58TiO2 has been investigated using X-ray powder diffraction and a network analyzer. The structural transition from columbite and rutile to ixiolite was influenced by both the sintering temperature as well as the amount of CuO. These influences, however, were competing. Therefore, it is assumed that the different constitutions of crystal structure of ZnNb2O6–TiO2 samples due to increase either the sintering temperature or the amount of CuO lead to considerable variation in the microwave dielectric properties. The τf was modified to ∼0 ppm/°C, as a result of the variation in phase constitutions as a function of composition.

Influence of Copper(II) Oxide Additions to Zinc Niobate Microwave Ceramics on Sintering Temperature and Dielectric Properties

The effect of CuO additions on the firing temperature of ZnNb2O6 ceramics was investigated using dilatometry, transmission electron microscopy, and X‐ray diffractometry. A 5 wt% CuO addition to ZnNb2O6 ceramics significantly lowered the firing temperature from 1150° to ∼900°C. The presence of a CuO‐rich intergranular phase in the specimen was observed and was evidence of the formation of a liquid phase during sintering. The composition of the liquid phase was (ZnCu2)Nb2O8. In particular, the low‐fired ZnNb2O6 ceramics had good microwave dielectric characteristics—Q×f= 59 500, ɛr= 22.1, τf=–66 ppm/oC. These properties were correlated with the formation of a second phase, (ZnCu2)Nb2O8.

The effect of CuO addition on the sintering of lime

The sintering of lime was carried out with 1–4 wt.% CuO in the temperature range 1500–1650°C. A double calcination process was adopted in the study. The result showed that without additive the densification was 88% and with additive it maximised to 93% of the theoretical value at 1550°C with 1 wt.% CuO. The density decreased due to the presence of large closed pores with a higher percentage of CuO. Hydration resistance was measured at 50 oC in 95% relative humidity through the weight gain after 3 h. Addition of CuO up to 2 wt.% improved the hydration resistance, but it was not significantly high in comparison to that of 1 wt.% CuO. The use of a higher level of CuO in lime did not show any further improvement in hydration resistance. The CaO forms a low melting compound (2CaO.CuO) with CuO which helps liquid phase sintering of lime. When the liquid content increased in the sinterred lime grain growth takes place simultaneously along with pore growth

Effect of CuO addition on the high-field and high-pressure behavior of microwave-prepared lead vanadate glasses

High-field and high-pressure behavior of microwave-prepared xCuO:(45−x) PbO: 55V2O5 (x = 0 to 20) glasses were investigated for the first time. It was found that the addition of CuO significantly alters the nonlinear I–V characteristics of these glasses; while the glasses with x = 10 exhibit a current-controlled negative resistance behavior associated with a memory type transition, glasses with x = 15 show a threshold-type behavior. Remarkable differences were also noticed in the high-pressure electrical resistivity behavior between the low- and high-CuO-containing glasses. Corroborative thermal, electrical, microscopic, and spectroscopic measurements were carried out to understand the structure–property relations. A structural model was proposed, which is based on the chemical nature of the constituents present in the glasses. The model accounts well for the various observed properties of these glasses.

Effect of CuO Addition on the Magnetic and Microwave Properties of YIG

The structure, magnetic and microwave properties of polycrystalline YIG prepared by a conventional ceramic method with the addition of a small quantity of CuO as a sintering agent, were studied using X-ray diffractometry, magnetometry and ferromagnetic resonance experiments. Samples sintered with the sintering agent consisted of mainly a cubic YIG structure. Small amounts of Cu ferrite and grain boundary phase were formed in specimens with CuO content above 1.5 wt% during sintering. Saturation magnetization and Curie temperature of specimens were almost independent of the content of CuO. Sintering temperature for YIG can be reduced by about 100 K by adding 0.5-1.0 wt% CuO without any change in saturation magnetization and Curie temperature. The specimen prepared with CuO showed improved microwave property.

Effect of CuO addition in Bi-Sr-Ca-Cu-O and Y-Ba-Cu-O ceramics

The effect of adding CuO matrix to Bi1·6Pb0·4Sr2Ca2Cu3Oδ and Y1Ba2Cu3Oδ superconductors was investigated through resistivity, XRD, SEM, thermoelectric power (TEP), and ac magnetization studies. Samples with as low as 20% (by weight) of the superconducting phase showed superconducting transition in resistivity-temperature (R-T), with the superconducting zero around 77 K in thermoelectric power, critical current (J c) values were evaluated by applying Bean’s critical state model. CuO could be added to the superconducting material without any significant deterioration in the quality of the samples, up to a concentration of as low as 40% (by weight) of the superconducting material.

Low-firing of CuO-doped anatase

The effect of CuO additions on the firing temperature of the anatase phase of TiO 2 has been investigated using X-ray diffraction, transmission electron microscopy, and dilatometry. It was found that the addition of 2 wt% CuO to TiO 2 anatase significantly lowered the sintering temperature to ∼900°C. The presence of a CuO-rich intergranular phase in the sample was observed and was attributed to the presence of a liquid phase during sintering. The addition of CuO to anatase phase TiO 2 lowered the phase transformation temperature as well as the temperature of a shrinkage anomaly. This shrinkage anomaly is apparent in a temperature region showing a reversal of the shrinkage rate. The low-firing of CuO-doped anatase was attributed to the association of two distinct mechanisms: the formation of CuO-rich liquid phase at higher temperatures and a shrinkage onset present at lower temperatures associated with the phase transformation.

Effect of CuO additives on the reversibility of zirconia crystalline phase transitions

We have studied the influence of the differents atmospheres on the sintering of CuO-doped-zirconia ceramics. After an annealing treatment in a reducing atmosphere, we have found nanoparticles of metallic copper in triple points and in the grains of the sintered zirconia. Furthermore, the influence of the intergranular Y2Cu2O5 phase on the tetragonal to monoclinic phase transition and the crystalline structure of zirconia is discussed with respect to results obtained from X-ray diffraction, differential thermal analysis, Raman spectroscopy and High Resolution Transmission Electron Microscopy.

Effect of CuO addition on the electrical and dielectrical properties of semiconducting barium titanate ceramics

A number of studies [1-5] on barium titanate ceramiccapacitors with grain boundary barrier layers (referred to as GBBL capacitors) have been made in order to produce materials with the large capacitances necessary for the miniaturization of electronic circuits. The GBBL capacitors, which may be characterized by the structure consisting of sintered conductive grains with highly insulating thin layers along the grain boundaries, have mainly been prepared in the following three ways: 1. sintering high purity BaTiO3 in a reducing ambient (hydrogen or nitrogen/hydrogen) atmosphere to obtain the semiconducting ceramic bodies, followed by back oxidation of the bodies in an oxidiizing ambient (oxygen or air) atmosphere to form oxidized intergranular barrier layers; 2. making v;dence-controlled semiconducting barium titanate ceramics using a conventional procedure for the preparation of ceramics and then forming an insulating barrier layer by a second firing of the ceramics with appropriate metal oxides painted on the ceramic surfaces; 3. using a single.fire process, in which both an n-dopant (Sb203 for instance) and a p-dopant (CuO for instance) are simultaneously doped in barium titanate host materials to produce semiconducting ceramic bodies with an insulating grain boundary phase formed by precipitation of the p-dopant during cooling of the sintering process. It should be important to clear the behaviour patterns of both the electrical and the dielectrical grain boundary properties in barium titanate GBBL ceramics from the view points of both theory and the application, though