Substitution Of Zn For Cu Research Articles

Substitution of Zn for Cu in Mg–Y–Zn alloys designed for fracturing ball

The microstructure, mechanical properties and degradation behaviour of Mg95Y3Zn2 (MYZ), Mg95Y3Zn1Cu1 (MYZC), and Mg95Y3Cu2 (MYC) (at.-%) alloys have been studied. All the alloys mainly contain α-Mg matrix and LPSO phase. By substituting Zn for Cu, the composition of the LPSO phase transformed from Mg–Y–Zn to Mg–Y–Zn–Cu, and then to Mg–Y–Cu. The ultimate compressive strength is 227, 231 and 238 MPa, respectively. The MYC alloy exhibited much higher degradation rate than MYZC and MYZ alloys. The strong galvanic coupling effect between LPSO phase and the matrix, the grain size refinement and the weak protection from the corrosion product layer are responsible for the high degradation rate. It is suggested that the newly developed MYC alloy is promising for fracturing ball application.

The Effect of Partial Substitution of Non-Magnetic Impurity Zn on the Magnetic Moments of Eu<sub>1.88</sub>Ce<sub>0.12</sub>Cu<sub>1-y</sub>Zn<sub>y</sub>O<sub>4+α-δ</sub>

Structure and magnetic properties of electron-doped superconducting cuprates have been investigated in order to study the effect of magnetic impurity to its physical properties. Here, we reported structure and magnetic properties of Eu1.88Ce0.12Cu1-yZnyO4+α-δ (ECCZO) with y = 0 and 0.03. The properties of ECCZO have been studied from X-ray diffraction data and temperature dependence of magnetic susceptibility data, to elucidate the effect of partial substitution of non-magnetic impurity Zn for Cu to its structure, Tc and the value of magnetic moments per unit volume extracted from susceptibility data in normal state. Magnetic-susceptibility measurements were carried out down to 2 K on-field cooling at 5 Oe for Eu1.88Ce0.12Cu1-yZnyO4+a-d with y = 0 and 0.03. For ECCZO sample with y = 0 and d = 0.0669 indicated the change of magnetic behavior from paramagnetic to diamagnetic below 12 K which is addressed to the Tc onset of this samples. Diamagnetic behavior is observed starting from about 12 K. Above 12 K, all samples show paramagnetic behavior with the values of the magnetic moment in every volume unit increased with increasing Zn.

Study of transport and magnetic properties of electron-doped superconducting cuprates Eu1.85Ce0.15Cu1-yZnyO4+α-δ

Transport and magnetic properties of electron-doped superconducting cuprates Eu1.85Ce0.15Cu1-yZnyO4+α-δ (ECCZO) with y = 0, 0.01, 0.02 and 0.05 have been studied from electrical resistivity and magnetic susceptibility measurements, in order to elucidate the effect of partially Zn-substitution for Cu to its superconductivity and localization of electron in normal state. It has been found that the onset of the critical temperature (Tc) from electrical resistivity and magnetic susceptibility measurements was observed at 13 K for y = 0 and δ values of 0.095. With increasing Zn concentration, the onset of Tc disappeared, indicating the destruction of superconductivity properties by Zn. Moreover, 0.01 of Zn substitution for Cu decreased radius of localization of electron (r) in normal state at low temperatures that may related to the evident of stripe-pinning effects by Zn in electron-doped system of ECCZO. Analysis of magnetic susceptibility data in normal state found a Zn-induced local moments in electron-doped high-Tc superconducting cuprates of ECCZO as observed in hole-doped cuprates.

Study of structure and resistivity of electron-doped superconducting cuprates Eu1.85Ce0.15Cu1-yZnyO4+α-δ

Partially Zn-substituted for Cu in electron-doped superconducting cuprates of Eu1.85Ce0.15Cu1-yZny4+α-δ (ECCZO) with y = 0, 0.01, 0.02, 0.05 and various δ values have been studied in order to elucidate the effect of nonmagnetic impurity of Zn to their structure and resistivity properties in the electron-doped cuprates. It has been found that the main peaks of T’ structures are clearly observed in all samples. Superconductivity disappeared with Zn substitution for Cu in electron-doped system of ECCZO.

Structural and Magnetic Properties of Ba3[Cu0.8−xZnxMn0.2]2Fe24O41 Z‐Type Hexaferrites

We report on the synthesis and characterization of Ba3[Cu0.8−xZnxMn0.2]2Fe24O41 (x = 0.0, 0.2, 0.4, 0.6, and 0.8) barium hexaferrites. The samples were prepared by high‐energy ball‐milling technique and double‐sintering approach. The effects of Zn substitution for Cu on the structural and magnetic properties of the prepared samples were investigated using X‐ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). XRD patterns of the samples revealed the presence of a major Z‐type hexaferrite phase, together with secondary M‐type and Y‐type phases. The magnetic results indicated that the saturation magnetization increased slightly with increasing the Zn content, while the coercivity and magnetocrystalline anisotropy field exhibited a decreasing tendency with the increase of Zn content. The thermomagnetic curves revealed the complex magnetic structure of the prepared samples and confirmed that the Curie temperature of the magnetic phases decreased with increasing x as a result of the reduction of the strength of the superexchange interactions.

Glassy behavior of diluted Cu-Zn ferrites

The magnetic behavior of Zn substituted Cu-Zn spinel ferrites having chemical formula Cu1−xZnxFe2O4 (x = 0.7, 0.8, 0.9 and 1.0) has been studied by SQUID magnetometry, by means of magnetic hysteresis, field-cooled (FC) and zero-field-cooled (ZFC) magnetization, memory effect and low field ac susceptibility measurements. These measurements suggest that the ferrimagnetic phase of the x ≤ 0.8 samples is gradually turned into a spin glass (x ≥ 0.9). The compound with x = 0.9 exhibits the typical dynamical behavior of spin glasses, with indication of aging, rejuvenation and memory effects. The evolution of the magnetic properties of Cu-Zn spinel ferrites with substitution of Zn for Cu is discussed.

The Effect of Microalloying Additions in Aluminum Alloys on Intermetallic Electrochemistry and Dissolution Behavior

Advances in aluminum alloy processing have enabled more reliable control of low-level alloying additions. Small alloying additions, often referred to as “microalloying” have been reported to affect strengthening mechanisms, intergranular corrosion resistance, stress corrosion cracking resistance, and other properties [1,2]. In some cases, notable improvements in resistance to corrosion and stress corrosion cracking have been reported. Microstructural characterization has shown that some low-level alloying additions can be dissolved into intermetallic compounds that form during natural or artificial aging. This raises the possibility that alloying alters intermetallic electrochemistry and intermetallic dissolution behavior. For example, MgZn2 dissolves Cu as aging time of 7XXX alloys increases [3]. Potentiodynamic polarization measurements of bulk synthesized Mg(Zn,Cu)2 with Cu concentrations of up to 17 wt.% show that dissolution kinetics are significantly ennobled and the breakdown potential of the phase is increased. Similar effects are observed when Cu is added to Al3Mg2. Zn additions to Al2CuLi result in an isomorphic substitution of Zn for Cu in the structure of the intermetallic compound and a decrease in the reactivity of the phase. The changes in intermetallic electrochemical behavior due to microalloying have not yet been linked to overall alloy corrosion rates or modes and detailed characterization of the relationships between alloy chemistry, alloy processing, intermetallic chemistry and dissolution behavior and overall alloy corrosion behavior are warranted. In this presentation, the effect of microalloying on the dissolution behavior of MgZn2, Al2CuMg is reported. Bulk crystals of pure MgZn2, Al2CuMg and were synthesized then remelted with low-level alloying additions (< 1 at.%) followed by heat treating to form the desired phases. Transition and rare-earth metals typically have low solubility in Al, resulting in these elements incorporating into existing intermetallics or forming alternate phases. These alternate phases may also result in suppressing the formation of Al2CuMg and MgZn2 by arranging into more energetically favorable phases. Zn additions do not readily incorporate into bulk Al2CuMg, instead forming particles of Al0.38Cu0.46Mg0.16 containing 1-5%Zn and increasing the corrosion rate of the particle by an order of magnitude. Conversely, Cu additions to MgZn2 showed significant incorporation of Cu on Zn sites in the MgZn2 structure, as well as more noble corrosion behavior. Furthermore, this project explores the effect of other elemental alloying additions whose microstructural effects have been studied in literature, such as Ag and Ce, to see what corrosion effects may also take place. Phase identification was based on structural and chemical characterization. Powder x-ray diffraction (XRD) was used to confirm structure and energy dispersive spectroscopy (EDS) was used to characterize chemistry. Electrochemical characterization was carried out using open circuit potential and potentiodynamic polarization measurements performed with an electrochemical microcell. In this presentation, the effect of Cu microalloying on the structure and electrochemistry of MgZn2 and Zn microalloying on Al2CuMg will be summarized. How microalloying affects dissolution rates and modes of corrosion will be described. How changes in intermetallic electrochemistry affect alloy corrosion behavior will also be discussed.

New data on hemihedrite from Arizona

AbstractHemihedrite from the Florence Lead-Silver mine in Pinal County, Arizona, USA was first described and assigned the ideal chemical formula Pb10Zn(CrO4)6(SiO4)2F2, based upon a variety of chemical and crystal-structure analyses. The primary methods used to determine the fluorine content for hemihedrite were colorimetry, which resulted in values of F that were too high and inconsistent with the structural data, and infrared (IR) spectroscopic analysis that failed to detect OH or H2O. Our reinvestigation using electron microprobe analysis of the type material, and additional samples from the type locality, the Rat Tail claim, Arizona, and Nevada, reveals the absence of fluorine, while the presence of OH is confirmed by Raman spectroscopy. These findings suggest that the colorimetric determination of fluorine in the original description of hemihedrite probably misidentified F due to the interferences from PO4and SO4, both found in our chemical analyses. As a consequence of these results, the study presented here proposes a redefinition of the chemical composition of hemihedrite to the ideal chemical formula Pb10Zn(CrO4)6(SiO4)2(OH)2. Hemihedrite is isotypic with iranite with substitution of Zn for Cu, and raygrantite with substitution of Cr for S. Structural data from a sample from the Rat Tail claim, Arizona, indicate that hemihedrite is triclinic in space groupP1,a= 9.4891(7),b= 11.4242(8),c= 10.8155(7) Å, α = 120.368(2)°, β = 92.017(3)°, γ = 55.857(2)°,V= 784.88(9) Å3,Z= 1, consistent with previous investigations. The structure was refined from singlecrystal X-ray diffraction data toR1= 0.022 for 5705 unique observed reflections, and the ideal chemical formula Pb10Zn(CrO4)6(SiO4)2(OH)2was assumed during the refinement. Electron microprobe analyses of this sample yielded the empirical chemical formula Pb10.05(Zn0.91Mg0.02)∑ = 0.93(Cr5.98S0.01P0.01)∑ = 6.00Si1.97O34H2.16based on 34 O atoms and six (Cr + S + P) per unit cell.

Tunable electronic properties and low thermal conductivity in synthetic colusites Cu26−xZnxV2M6S32 (x ≤ 4, M = Ge, Sn)

We have first synthesized Cu26−xZnxV2M6S32 (x ≤ 4, M = Ge, Sn) with the cubic colusite structure and measured the thermoelectric properties. For both M = Ge and Sn, the samples with x = 0 show moderately large thermopower of +27 μV/K at 300 K. The metallic conduction of p-type carriers and Pauli-paramagnetic behavior are consistent with the electron-deficient character expected from the formal charge Cu261+V25+M64+S322−. The substitution of Zn for Cu results in significant increases in both the electrical resistivity and thermopower. The resistivity of the samples with x = 4 displays a three-dimensional variable-range hopping behavior at low temperatures. These facts indicate that the doped electrons fill the unoccupied states in the valence band and thereby the Fermi level moves to the localized electronic states at the top of the band. The lattice thermal conductivity is as low as ∼1 W/Km at 300 K for all samples. The structural and thermoelectric properties of the colusites are discussed in comparison with those of doped tetrahedrite Cu12−xZnxSb4S13.

Thermoelectric properties of Cu2Ga4Te7 based compounds with Zn substitution for Cu and Ga

We present two series of Cu2Ga4Te7‐based compounds with Zn substituting for Cu (Cu‐poor) and Ga (Ga‐poor), and have observed enhanced thermoelectric performance. Generally, the Seebeck coefficient (α) and lattice thermal conductivity (κL) increase and electrical conductivity (σ) decreases with the Zn content increasing. The variation in electrical properties might be mainly due to the formation of antisite defects ( and ), the acceptors. The defects increase the local density of states (DOS) near the Fermi level and effective mass, leading to the increase in α, while on the other hand, they widen the bandgap (Eg) leading to the degradation of the electrical conductivity. The gradual enhancement in κL is attributed to the reduced phonon scattering resulting from the decrease in vacancy concentration. As a result, we attained the maximum ZT value of 0.46 for Cu‐CGT and 0.47 for Ga‐CGT at ∼770 K with a proper Zn content, which is about 20–22% higher than that of intrinsic Cu2Ga4Te7.

Effects of Zn doping on crystal structure, Raman spectra and superconductivity of SmBa2Cu3O7−δ systems

Abstract Polycrystalline SmBa 2 Cu 3− x Zn x O 7− δ (SBCZO) ( x = 0.0–0.4) samples are prepared by the usual solid-state reaction technique. The effects of Zn doping on the structure, the grain morphology, Raman spectra and electronic transport properties of SBCZO systems have been investigated. The orthorhombic structure of the samples does not change remarkably. The samples become denser and grain boundary becomes unclear with the increase of Zn content. Raman spectra exhibit different features with increasing Zn content which shows that Zn ions act as strong scattering centers to the charge carriers in the CuO 2 planes, enhance the disorder of the CuO 2 planes and increase oxygen depletion in Cu O chains. The measurements of the resistivity show that the superconducting transition temperature T c decreases rapidly and the superconducting transition width increases gradually with increasing Zn contents. Furthermore, the changes of the samples’ normal state resistivity from metallic to semi-conducting behavior show the increase of heterogeneities with increasing Zn content which causes inter-grain or intra-grain disorders. All the results suggest that lattice disorder in the CuO 2 planes, the oxygen content change in Cu O chains and local weak superconductivity regions due to the substitution of Zn for Cu are related to the suppression of T c in the SBCZO systems.

The effect of heat treatment on superconductivity of Zn‐doped YBa2Cu3‐xZnxO7‐y

AbstractYBa2Cu3‐xZnxO7‐y compounds with x = 0, 0.05, 0.15, and 0.30 have been synthesized by standard solid state reaction method. The crystal structure, lattice parameters, and oxygen content are not changed by the substitution of Zn for Cu since both valence state and ionic radius are almost identical for Zn and Cu elements in YBa2Cu3‐xZnxO7‐y. However, the superconducting transition temperature Tc decreases with the increase of Zn content, reflecting the Tc‐suppression effect of Zn substitution. Heat treatment experiments indicate that the heat treatment at low temperature is beneficial to improve the superconductivity of the sample. But Tc decreases with the increase of annealing temperature when the treatment temperature is above 300°C, and finally the superconductivity disappears at approximately 920°C, 700°C and 550°C for the samples with x = 0.0, 0.05 and 0.15, respectively. Our experiments indicate that the superconductivity of the sample with higher Zn content is more sensitive to the oxygen content, and a small decrease in the oxygen content can lead to a considerable decrease of Tc.

Development of Cu-spin correlation in Bi1.74Pb0.38Sr1.88Cu1−yZnyO6+δhigh-temperature superconductors observed by muon spin relaxation

A systematic muon-spin-relaxation study in Bi-2201 high-Tc cuprates has revealed for the first time that the Cu-spin correlation (CSC) is developed at low temperatures below 2 K in a wide range of hole concentration where superconductivity appears. The CSC tends to become weak gradually with increasing hole-concentration. Moreover, CSC has been enhanced through the 3% substitution of Zn for Cu. These results are quite similar to those observed in La-214 high-Tc cuprates. Accordingly, it has been suggested that the intimate relation between the so-called spin-charge stripe correlations and superconductivity is a universal feature in hole-doped high-Tc cuprates. Furthermore, apparent development of CSC, which is suppressed through the Zn substitution oppositely, has been observed in non-superconducting heavily overdoped samples, being argued in the context of a recently proposed ferromagnetic state in heavily overdoped cuprates.

How the substitution of Zn for Cu destroys superconductivity in YBCO system?

Understanding the mechanism of suppression of superconductivity in perovskite cuprates is as important as to discover the cause of its evolution. Substituting Zn for Cu is known to rapidly suppress the superconductivity in these perovskites but the mechanism is still not understood. To throw some light on this, polycrystalline YBa 2(Cu 1− x Zn x ) 3O 7− δ samples ( x = 0.0–0.06) were synthesized and investigated using X-ray diffraction, titration, resistivity, magnetization, X-ray absorption and photoemission measurements. Results show that their oxygen stoichiometry ( δ) changes on Zn substitution affect their normal state resistivity as well as their T c . However, the observed changes cannot be accounted for solely on the basis of changes in δ. Zn cation is found to act as strong scattering centre in the lattice that causes local lattice distortion (LLD). It also induces local magnetic moment as evidenced from our magnetization results. It is concluded that a combination of Δ δ, LLD and magnetic pair breaking effect is responsible for the observed rapid suppression of superconductivity.

Effect of Zn substitution for Cu on Ca2-xNaxCuO2Cl2 near the hole concentration of 18 per Cu

A weakening of superconductivity upon substitution of Cu by Zn (0.5–1%) is observed in a high-Tc cuprate, Ca2-xNaxCuO2Cl2, near the hole concentration of 18 per Cu. The superconducting transition temperature and its volume fraction, estimated by magnetic susceptibility, exhibit a sizable anomaly for x=0.12–0.14, where the slowing down of Cu spin fluctuations below 5 K is demonstrated by muon spin relaxation experiments. These observations are in close resemblance to other typical cuprates including YBa2Cu3O7-δ, and Bi2Sr2Ca1-xYxCu2O8+δ, providing further evidence that Zn-induced “stripe” correlation is a universal feature of high-Tc cuprate superconductors common to that of La2-xAxCuO4 (A=Ba, Sr).

Effects of substitution on quantum spin system having a nearly non-magnetic state and antiferromagnetic long-range order

The cuprate Cu2CdB2O6 has two Cu sites (Cu1 and Cu2). Cu1 spins are in a nearly non-magnetic state because of formation of AF dimers, while Cu2 spins form antiferromagnetic (AF) long-range order. We investigated effects of substitution of Zn for Cu on magnetism of this cuprate. The reduction in AF transition temperature per Zn is small in comparison with other quasi-one-dimensional antiferromagnets. We consider that the system of the Cu2 spins is a two-leg ladder.

Heat capacity proportional toT2induced by Ru substitution inCaCu3(Ti4−xRux)O12(x≈0.5)

The effect of Ru substitution for Ti on the ground-state properties of three-dimensional antiferromagnet (AF) ${\text{CaCu}}_{3}{\text{Ti}}_{4}{\text{O}}_{12}$ is studied by means of magnetic susceptibility and heat-capacity measurements. A small amount of Ru substituted for Ti suppresses AF long-range order and induces a new intermediate state with ${T}^{2}$-proportional heat capacity, which shows a clear contrast to a simple spin-dilution effect demonstrated by the Zn substitution for Cu. Ru substitution also creates a finite density of state at the Fermi level while keeping nominal valence of Cu ions to be $2+$, which is essential to a novel insulator-to-metal crossover driven by an isovalent substitution of ${\text{Ru}}^{4+}$ for ${\text{Ti}}^{4+}$.

Substituted M[sub x]Cu[sub 6−x]Sn[sub 5] Compounds (M=Fe, Co, Ni, Zn) Designing Multicomponent Intermetallic Electrodes for Lithium Batteries

A strategy to exploit substituted M x Cu 6-x Sn 5 (M = Fe, Co, Ni, Zn) electrodes with NiAs-type structures that transform on electrochemical lithiation in lithium cells to intermediate face-centered-cubic Li 2 Cu 1-y M y Sn structures before Li z Sn alloys (1 < z < 4.4) are produced is discussed. Zn substitution for Cu is possible only to x as 1 before the onset of secondary phases, whereas Co and Ni substitution appears to maintain the NiAs-type structure for the whole range of x (0 ≤ x ≤ 5). Substituted electrodes provide higher rechargeable capacities than Cu 6 Sn 5 . The results of the study have implications for tailoring and optimizing (i) the design of multicomponent intermetallic electrode structures containing elements that are either active or inactive towards lithium, (ii) electrode compositions, and (iii) the reversibility of lithium insertion/metal displacement reactions in intermetallic electrode systems.

Effects of Zn doping on YBaCuO superconductor

AbstractIn this work we present a study of Zn impurity effects on the YBa2Cu3O7–δ high Tc superconducting ceramics prepared by the solid state reaction method. X‐ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal analysis (DTA) techniques, and resistivity measurements are used to characterize the YBa(Cu1–xZnx)3O7–δ samples. The obtained results show that, for example, the value of the transition critical temperature is decreasing up to 80 K caused by the substitution of Zn for Cu in the interval 0 ≤ x ≤ 0.01. Also, the peritectic transformation of superconducting phase undergoes a displacement to lower temperatures compared with pure YBaCuO. On the basis of the obtained results, the effects of Zn doping on the structural and electronic properties are explained. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Hole Doping Effects on Spin-gapped Na2Cu2TeO6 via Topochemical Na Deficiency

We report the magnetic susceptibility and NMR studies of a spin-gapped layered compound Na2Cu2TeO6 (the spin gap $\Delta\sim$ 250 K), the hole doping effect on the Cu2TeO6 plane via a topochemical Na deficiency by soft chemical treatment, and the static spin vacancy effect by nonmagnetic impurity Zn substitution for Cu. A finite Knight shift at the $^{125}$Te site was observed for pure Na2Cu2TeO6. The negative hyperfine coupling constant $^{125}A_{tr}$ is an evidence for the existence of a superexchange pathway of the Cu-O-Te-O-Cu bond. It turned out that both the Na deficiency and Zn impurities induce a Curie-type magnetism in the uniform spin susceptibility in an external magnetic field of 1 T, but only the Zn impurities enhance the low-temperature $^{23}$Na nuclear spin-lattice relaxation rate whereas the Na deficiency suppresses it. A spin glass behavior was observed for the Na-deficient samples but not for the Zn-substituted samples. The dynamics of the unpaired moments of the doped holes are different from that of the spin vacancy in the spin-gapped Cu2TeO6 planes.