Impurity Cu2 Research Articles

Trace Metal Impurities Effects on the Formation of [64Cu]Cu-diacetyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM).

[64Cu]Cu-diacetyl-bis(N4-methylthiosemicarbazone) ([64Cu]Cu-ATSM) is a radioactive hypoxia-targeting therapeutic agent being investigated in clinical trials for malignant brain tumors. For the quality management of [64Cu]Cu-ATSM, understanding trace metal impurities' effects on the chelate formation of 64Cu and ATSM is important. In this study, we conducted coordination chemistry studies on metal-ATSM complexes. First, the effects of nonradioactive metal ions (Cu2+, Ni2+, Zn2+, and Fe2+) on the formation of [64Cu]Cu-ATSM were evaluated. When the amount of Cu2+ or Ni2+ added was 1.2 mol or 288 mol, equivalent to ATSM, the labeling yield of [64Cu]Cu-ATSM fell below 90%. Little effect was observed even when excess amounts of Zn2+ or Fe2+ were added to the ATSM. Second, these metals were reacted with ATSM, and chelate formation was measured using ultraviolet-visible (UV-Vis) absorption spectra. UV-Vis spectra showed a rapid formation of Cu2+ and the ATSM complex upon mixing. The rate of chelate formation by Ni2+ and ATSM was lower than that by Cu-ATSM. Zn2+ and Fe2+ showed much slower reactions with the ATSM than Ni2+. Trace amounts of Ni2+, Zn2+, and Fe2+ showed little effect on [64Cu]Cu-ATSM' quality, while the concentration of impurity Cu2+ must be controlled. These results can provide process management tools for radiopharmaceuticals.

Theoretical studies on the local structure and spin Hamiltonian parameters for Cu2+ ions in LiTaO3 crystal.

The local structure and spin Hamiltonian parameters (SHPs) g factors (gx , gy , gz ) and the hyperfine structure constants (Ax , Ay , Az ) for Cu2+ doped in the LiTaO3 crystal are theoretically investigated by the perturbation formulas for a 3d9 ion under rhombically elongated octahedral based on the cluster approach. The impurity Cu2+ was assumed to occupy the host trigonally-distorted octahedral Li+ site and experience the Jahn-Teller (JT) distortion from the host trigonal octahedral [TaO6 ]10- to the impurity rhombically elongated octahedral [CuO6 ]10- . Based on the calculations, the impurity-ligand bond lengths parallel and perpendicular to the C2 -axis are found to be R|| (≈ 2.305 Å) and R⊥ (≈ 2.112 Å) for the studied [CuO6 ]10- cluster, with the planar bond angle θ (≈ 78.2°). Meanwhile, the ground-state wave function for Cu2+ center in LiTaO3 was also obtained. The calculated SHPs based on the above local lattice distortions agree well with the experimental data, and the results are discussed.

Mechanism of ultrasound-assisted copper cementation in zinc sulfate solution

The ultrasound-assisted copper cementation in zinc sulfate solution was investigated from microscopic and macroscopic views. The effect of ultrasound on the morphology of cemented product and Cu2+ removal efficiency under different conditions was analyzed by SEM with EDS, optical microscopy (OM), XRD and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The results show that the ultrasound has a thermal effect on the solution, and higher temperature can promote copper cementation obviously. It revealed a definite correlation between the morphology of cemented product and the removal of impurity Cu2+ in the solution. The increased power of ultrasound can promote Cu cementation, and Cu removal can be up to >99 % when the ultrasound power reaches 1500 W, suggesting that the powerful ultrasound strengthens diffusion in the bulk solution and through the porous product layer with a dendrite structure. The kinetics fitted results and the calculated activation energy (Ea = 10.86 kJ/mol) from the double exponential model indicated that the diffusion step governs ultrasound-assisted cementation, and the diffusion rate k2 increases with the power of the ultrasound field. However, the ultrasound also enhances the hydrogen evolution reaction between zinc and proton in the solution with a low pH level at the same time, leading to excessive zinc consumption and precipitation of basic zinc sulfates. It was actually unfavorable to economical purification for zinc electrowinning.

Studies on the EPR parameters and local angular distortion for the tetragonal Cu2+ center in CaWO4 crystal.

The electron paramagnetic resonance (EPR) parameters-g factors gi (i = || and ⊥) and hyperfine structure constants Ai (M) and Ai (N), with M and N belonging to isotopes 63 Cu2+ and 65 Cu2+ -and local structure of Cu2+ ion occupying W6+ site in CaWO4 crystal are theoretically studied based on the perturbation formulas of these parameters for a 3d9 ion under tetragonally elongated tetrahedra. In these formulas, the ligand orbital (LO) and spin-orbit coupling (SOC) contributions are included due to the shorter impurity-ligand distance R (≈1.83 Å) and hence the strong covalency of the studied [CuO4 ]6- cluster, and the related molecular orbital coefficients are quantitatively determined from the cluster approach in a uniform way; meanwhile, the required crystal field (CF) parameters for the tetragonally distorted tetrahedron (TDT) are estimated from the superposition model and the local structure of the impurity Cu2+ center. According to the calculation, the bond angle θ between the four equivalent Cu2+ -O2- bonds and the C4 axis in the CaWO4 :Cu2+ is found to be about 2.1° smaller than that (θ0 ≈ 54.74°) for an ideal tetrahedron due to the Jahn-Teller (JT) effect and the size mismatch. The fitted results agree well with the observed values, and the validity of the present assignment for the local structure of the Cu2+ center is also discussed.

Studies of the EPR parameters and tetragonal distortion for the Cu2+ center in aluminium oxide

The electronic paramagnetic resonance (EPR) parameters (g factor gi , and hyperfine structure constants Ai , with i = || and ⊥) and tetragonal distortion of the Cu2+ center in Al2O3 are unified interpreted from the perturbation formulas for a 3d9 ion in tetragonally elongated octahedral. In the calculations, the impurity Cu2+ is found to occupy the host trigonally-distorted octahedral Al3+ site with the tetragonal elongation distortion due to the Jahn–Teller effect, despite the original trigonal distortion of the host cation site. The contributions to EPR parameters from both the spin–orbit coupling of the central ion and that of the ligands are taken into account. The defect structure of the Cu2+ center (characterized by the relative tetragonal elongation ratio η ≈ 4.3% along the C 4 axis) was determined from the calculation. Furthermore, the calculated results agree well with the experimental data and need fewer adjustable parameters than the previous studies.

Studies of the Local Distortions for Cu2+ in Ba2Zn(HCOO)6·4H2O Single Crystal

The high-order perturbation formulas of the electron paramagnetic resonance (EPR) parameters for an orthorhombically elongated octahedral 3d9 cluster are adopted to analyze the local distortions of divalent copper in Ba2Zn(HCOO)6·4H2O (BZFA). The doped Cu2+ may substitute the host Zn2+ in the lattice, with different local environments from the original Zn2+, which can strongly affect its EPR parameters. In the calculations, the admixture of d-orbitals in the ground state for the impurity Cu2+ ion under orthorhombic symmetry is considered, and the required molecular orbital coefficients are determined from the cluster approach. The orthorhombic field parameters are correlated with the local lattice distortion (characterized by the axial elongation δz and the relative perpendicular bond length variation δr) and can be calculated from the superposition model. The theoretical EPR parameters based on the above local structure are in good agreement with the observed values, and the results are discussed.

Theoretical investigation on the optical and EPR spectra for Cu2+ -doped ZnO-CdS nanocomposites.

The three optical absorption bands and EPR parameters of the [CuO6 ]10- center in the ZnO-CdS composite nanopowders are theoretically studied from the perturbation formulas based on the cluster approach. In the formulas, the contributions to EPR parameters arising from the ligand orbital and spin-orbit coupling interactions via covalence effect are considered. For the studied [CuO6 ]10- cluster, the Cu-O bond lengths are suggested to show a relative elongation ratio ρ (≈ 4.1%) along the z-axis due to Jahn-Teller effect. The defect models suggested in this work are different from the previous assumption that the impurity Cu2+ can replace the host Zn2+ site when it enters the lattices of the ΖnO and ΖnS nanocrystals, forming the tetrahedral [CuΧ4 ]6- clusters (Χ=O, S). The validity of the proposed model is discussed. The differences between the present calculations and the previous ones for the interstitial Cu2+ center in ZnO nanocrystals are analyzed in view of the dissimilar impurity behaviors due to the new composition CdS and distinct preparation conditions.

Studies on EPR Parameters and Local Structures for the Rhombic Cu2+ Center in the ZnGeO4 · 6H2O Crystal

The electron paramagnetic resonance (EPR) parameters (g factors and hyperfine structure constants) and local structures for the impurity Cu2+ center in ZnGeO4 · 6H2O crystal are theoretically studied using the perturbation formulas of these parameters for a 3d9 ion in rhombically elongated octahedra. These formulas are based on a two-spin-orbit-parameter model in which the contributions to the EPR parameters due to both the spin-orbit parameter of the central 3dn ion and that of ligand ion are included. Based on the calculation, the relative axial elongation ratio ρ (≈7.3%) along z-axis and the relative planar bond length variation τ (≈4.3%) along x- and y-axes are found for [Cu(H2O)6]2+ cluster in ZnGeO4 · 6H2O crystal. The above local rhombic distortions of the Jahn–Teller nature around Cu2+ can suitably account for the axial and perpendicular anisotropies of the observed EPR parameters.

Investigations on the EPR parameters and defect structures due to Jahn-Teller effect for the Cu2+ and Ni+ centers in LiNbO3

The EPR parameters of the impurity Cu2+ and Ni+ in LiNbO3 are theoretically studied from the perturbation formulas for 3d9 ions under rhombically elongated and compressed octahedra, respectively. In both centers, the impurity Cu2+ and Ni+ ions was ascribed to occupy the host trigonally-distorted octahedral Li+ sites and the octahedrons experience the Jahn-Teller distortion from trigonal to rhombically -elongated and -compressed, respectively. The elongated [CuO6]10− cluster (and compressed [NiO6]11− cluster) are ascribed to suffering the axial elongation of 0.102 Å (and compression of 0.062 Å) along z-axis and the planar bonds are found to experience the relative variation of 0.023 Å (and 0.032 Å), respectively, due to the Jahn-Teller effect. The calculated EPR parameters based on the above lattice distortions agree reasonably with the experimental data, and the local structures of the impurity centers are discussed.

Theoretical studies of the EPR parameters and local structures for the two Cu2+ centers in Cd(HCOO)2 ·2H2 O.

Based on the studies of the electron paramagnetic resonance parameters for two types of the Cu2+ centers in Cd(HCOO)2 ·2H2 O by using the high-order perturbation formulas for a 3d9 ion in a rhombically elongated octahedron, local structure of the doped copper ion is determined. Research suggests that the impurity Cu2+ replaces the host Cd2+ and undergoes the local rhombic elongation distortion, characterized by the axial elongation ratios of 4.1%, and 3.8% along the z-axis and the planar bond length variation ratios of 3.8%, and 3.1% along the x-axis and y-axis, for Cu2+ Centers, I and II, respectively. The above slightly different axial elongation ratios and planar bond length variation ratios may suitably account for the slightly dissimilar axial g anisotropies Δg (≈0.351 and 0.339) and perpendicular g anisotropies δg (≈0.028 and 0.022) of the two centers, respectively.

Investigation of Spin Hamiltonian Parameters and Defect Structure of Cu2+ In Srcl2 Crystals

The spin Hamiltonian parameters (g-factors and hyperfine structure constants) and defect structure of tetragonal Cu2+ ion in SrCl2 are theoretically investigated, using the high-order perturbation formulas for 3d 9 ions in tetragonally elongated octahedra. In these formulas, the contributions to the spin Hamiltonian from the ligand orbital and spin-orbit coupling interactions are considered with respect to strong covalency. Based on the studies, the impurity Cu2+ is found to be located at a distance of about 0.42 A from the nearest chlorine plane. The signs of the hyperfine structure constants A|| and A⊥ are suggested. The theoretical spin Hamiltonian parameters show good agreement with the experimental values. The results are discussed.

Theoretical studies of the local structure of Cu2 + center in aluminium lead borate glasses by their EPR and optical spectra

The local structure of the Cu2+ center in aluminium lead borate glasses was theoretically studied based on the optical spectral data and high-order perturbation formulas of the electron paramagnetic resonance (EPR) parameters (g factors g||, g⊥ and the hyperfine structure constants A||, A⊥) for a 3d9 ion in a tetragonally elongated octahedron. In the calculations, the ligand orbital and spin–orbit coupling of the impurity Cu2+ are taken into account; the required crystal-field parameters are estimated from the superposition model. Based on the calculations, the defect model of the Cu2+ center was confirmed and the defect structure (i.e., the ligand O2− octahedron around Cu2+ is determined to suffer about 19.2% relative elongation along the C4 axis due to the Jahn–Teller effect) was acquired, and a negative sign for A|| and positive sign of A⊥ for the Cu2+ center were suggested in the discussion.

Investigation of the EPR parameters of the rhombic Cu2+ center in (NH4)2Mg(SO4)2·6H2O single crystal

The electron paramagnetic resonance (EPR) parameters (g factors gx, gy, gz and hyperfine structure constants Ax, Ay, Az) for Cu2+ in (NH4)2Mg(SO4)2·6H2O (DHMS) crystal are theoretically investigated using the high-order perturbation formulas of these parameters. In the calculations, the ligand orbital and spin–orbit coupling for the impurity Cu2+ are taken into account; the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the EPR parameters with the local structure of the impurity center. The ligand orbital and the spin–orbit coupling contributions are included on the basis of the cluster approach. Based on the calculation, the theoretical EPR parameters show good agreement with the observed values. The results are discussed.

Investigations on the Spin Hamiltonian Parameters for Cu2+ in NaCl and AgCl

The spin Hamiltonian parameters (g factors and hyperfine structure constants) for Cu2+ in NaCl and AgCl are investigated theoretically for the case of the 3d 9 ion in tetragonally elongated octahedra using high-order perturbation formulas for these parameters. Due to the Jahn–Teller effect, the impurity Cu2+ centers are found to experience relative elongations along the four-fold axis of about 0.15 and 0.08 A in NaCl and AgCl, respectively. The calculated spin Hamiltonian parameters are in good agreement with the experimental data. The local structures and EPR spectra of the systems are discussed.

Investigations on the defect structure and the spin Hamiltonian parameters for LaSrGa0.995Cu0.005O4 crystal

The defect structure and the spin Hamiltonian parameters (g factors g||, g⊥, the hyperfine structure constants A|| and A⊥ of Cu2+ and the superhyperfine parameters A||′ and A⊥′ of Ga3+) for LaSrGa0.995Cu0.005O4 crystal are systematically investigated on the basis of the perturbation calculations for these quantities of a tetragonally elongated octahedral 3d9 complex. Arising from the Jahn–Teller effect, the impurity Cu2+ center indicates the slightly larger relative tetragonal elongation ratio (≈4.0(1)%) than that (≈3.40(4)%) of the host Ga3+ site. The computed values of the spin Hamiltonian parameters agree well with the measured results. To the best of our knowledge, the superhyperfine parameters of Ga3+ are theoretically studied for the first time. The unusual superhyperfine anisotropy (A||′<A⊥′) for the present Ga3+ ligand with respect to the conventional rule (A||′>A⊥′) for the common anion ligands is ascribed to the opposite signs of the anisotropic terms for the [CuGa4]14+ cluster. The present studies reveal significant Cu2+–O2− orbital hybridization and local tetragonal elongation around Cu2+, reflecting, to a certain extent, similar behaviors of the CuO2 planes in oxide cuprates high Tc superconductors.

Theoretical studies of the local structures and electron paramagnetic resonance parameters for Cu2+ center in Zn(C3H3O4)2(H2O)2 single crystal

The electron paramagnetic resonance (EPR) parameters (g factors gxx, gyy, gzz and hyperfine structure constants Axx, Ayy, Azz) are interpreted by taking account of the admixture of d-orbitals in the ground state wave function of the Cu2+ ion in a Zn(C3H3O4)2(H2O)2 (DABMZ) single crystal. Based on the calculation, local structural parameters of the impurity Cu2+ center were obtained (i.e. Ra≈1.92 Å, Rb≈1.96 Å, Rc≈1.99 Å). The theoretical EPR parameters based on the above Cu2+−O2− bond lengths in the DABMZ crystal show good agreement with the observed values and some improvements have been made as compared with those in the previous studies.

Theoretical investigations of the spin Hamiltonian parameters and local tetragonal distortions for Cu2+ in crystalline and amorphous TeO2 and GeO2

The spin Hamiltonian parameters (i.e., anisotropic g factors and hyperfine structure constants) and local tetragonal distortions for Cu2+ in crystalline and amorphous TeO2 and GeO2 are theoretically investigated using the high-order perturbation formulas of these parameters for a tetragonally elongated octahedral 3d9 cluster. The impurity Cu2+ occupying the octahedral sites are found to experience the relative tetragonal elongation ratios of about 11.4% and 9.5% for crystalline TeO2 and GeO2 and 10.8% and 6.6% for amorphous TeO2 and GeO2, respectively, along the C4 axis due to the Jahn–Teller effect. This reveals the larger tetragonal elongation distortions for the Cu2+ centres in crystalline than amorphous systems (especially TeO2). The theoretical spin Hamiltonian parameters show good agreement with the experimental data. The results are discussed.

Electrodeposition of single phase CuInSe2 for solar energy harvesting: Role of different acidic additives

Single phase CuInSe2 (CIS) absorber material is required for producing high quality thin film solar cells, as the presence of impurity Cu2−xSe leads to short circuit of the cells. Traditionally, the deposition of single phase CIS requires the use of a suitable chelating agent to shift the Cu2+/Cu redox couple towards the redox potential of the In3+/In couple, and also an acid to adjust the pH of deposition bath around 2. We propose a novel idea of using suitable acids that could concurrently also serve as the chelating agent. Oxalic acid, acetic acid and hydrochloric acid were investigated on their ability to serve this dual function. We found that oxalic acid is the most promising additive because the CIS film deposited was densest and yielded the highest photocurrent.

Theoretical Studies on the Local Structure and Electron Paramagnetic Resonance Parameters for Cu2+ Centers in TiO2 with one Oxygen Vacancy Adjacent

Based on the defect model that the impurity Cu2+ in TiO2 on the octahedral Ti4+ site is associated with one oxygen vacancy VO along the C 2 axis, the electron paramagnetic resonance (EPR) parameters, i. e., the g factors gi (i = x;y; z) and the hyperfine structure constants At, of the Cu2+-VOcenter in TiO2 are calculated by using the perturbation formulas of these parameters for a 3d9 ion in a rhombically elongated octahedra. From this study, the impurity Cu2+ is found to be away from VO by a distance Dz (≈ 0:33 Å) along the C2 axis, meanwhile the four O2- ions in the plane perpendicular to the C2 axis may be shifted by Dx (≈ 0:28 Å) towards VO due to the electrostatic interaction between these ions and VO. The theoretical results based on the above local structure distortions show good agreement with the experimental data.

Spin-Hamiltonian Parameters and Defect Structure of the Copper (2+) Center in Lithium Borate

ABSTRACT The spin-Hamiltonian parameters (the anisotropic g factors g || and g ⊥ and the hyperfine structure constants A || and A ⊥) for the impurity Cu2+ in Li2B4O7 are theoretically investigated using the high-order perturbation formulas of these parameters for a 3d 9 ion in tetragonally elongated octahedra. In the calculation formulas, the tetragonal field parameters Ds and Dt are determined from the superposition model, by considering the relative axial elongation of the oxygen octahedron around Cu2+ due to the Jahn-Teller effect. Based on the calculations, the relative axial elongation of about 0.21 Å for the tetragonal Cu2+ center was found.