Doped Cu2 Research Articles

High-temperature ferromagnetism of Cu-doped PbPdO2 nanograin films

The single-phase, body-centered orthorhombic-structured, Cu-doped PbPdO2 films with a nanograin structure were synthesized by using the sol–gel spin-coating method and an oxidation treatment. It was found that large amounts of Pb vacancies exist in the nanograin film and Pb ions possess a mixed valence state of 2+ and 4+. Besides the superparamagnetism and the charge ordering state, the magnetic studies displayed that ferromagnetism, which can persist up to 380 K, exists in the Cu-doped PbPdO2 nanograin film. As a peculiar characteristic of the spin gapless semiconductor, the ferromagnetic saturation magnetization increasing unusually with temperatures above 300 K was also discovered. The bound magnetic polarons based on the Pb vacancies, the doped Cu2+ ions, and the Pb ions with a valence higher than 2+ were believed to be the origin of such high-temperature ferromagnetism.

Doping effects on the relaxation of frustration and magnetic properties of YMn0.9Cu0.1O3

The crystal structure and magnetic properties of hexagonal YMn0.9Cu0.1O3 single crystal are systematically investigated. The refinement results of XRD show the lattice constant decreases, which is unusually due to the doped Cu2+ ion has a larger ionic radius than the Mn3+ ions. The XPS results show that the coexistence of Mn2+, Mn3+ and Mn4+ ions in YMn0.9Cu0.1O3 single crystal. Magnetization measurements show that Cu doped YMn0.9Cu0.1O3 and parent YMnO3 have almost the same antiferromagnetic transition temperature TN, which indicates the AFM interaction is robust in the geometry frustrated system. Because doping directly destroy some of the Mn3+ ions nets, the relaxation of frustration of Mn in-plane 2D triangular geometry network leads to the significantly decrease of Mn3+ ions AFM interaction. In addition, the coexistence and competition between the ferromagnetic and antiferromagnetic interactions among the Mn2+, Mn3+ and Mn4+ ions lead to a complicated and irreversible magnetization behavior in YMn0.9Cu0.1O3 single crystal.

Optical and EPR studies of Cu2+ doped SnO2 thin films by spray pyrolysis

The study and application of thin film technology is entirely entered in to almost all the branches of science and technology. Semiconductor oxide thin films are materials with numerous applications in electronic and optoelectronic devices as well as some other applications such as protective coatings, heat mirrors and catalysis. In the context of world energy demand, particularly energy conversion, transparent conductive oxides based semiconductor oxides plays a crucial role in the development of new-fashioned thin film solar cells. Present study describing the synthesis and study of optical and structural characteristics of copper ions doped tin oxide (SnO2) is really more interesting for researchers due to its vast applications. Cu2+-doped tin oxide thin films were prepared by chemical spray pyrolysis synthesis and characterised by powder XRD, optical and EPR studies. Powder XRD data revealed that the crystal structure belongs to tetragonal rutile phase and its lattice cell parameters, average crystallite size were evaluated. Optical and EPR data confirmed that the doped Cu2+ enter into host material as distorted octahedral symmetry.

Preparation of new thermoluminescent material (100−x)B2O3–xLi2O: Cu2+ for sensing and detection of radiation

The copper-doped lithium borate glass as a thermoluminescent (TL) material (100−x) B2O3–xLi2O : Cu2+ (x= 20, 50 and 80 mol%) was prepared by the combustion method. The formation of (100 −x)B2O3–xLi2O : Cu2+ after doping 2, 3 and 5 ppm Cu2+, was characterized by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy. The TL characteristics of the synthesized material were studied at different parameters. The synthesized glass 50B2O3–50i2O : Cu2+ with 3 ppm of doped Cu2+, exhibited the superior TL properties than other glasses prepared in the current study. The spin-Hamiltonian parameters were assessed using the electron spin resonance spectra of 50B2O3–50Li2O : Cu2+ doped with 3 ppm Cu2+. The spin-Hamiltonian parameter values in the case of Cu2+ revealed that the ground state of Cu2+ was dx 2–y 2 orbital (\(^{\mathbf {2}}\text {B}_{\mathbf {1g}}\)) and the site symmetry around Cu2+ ion was distorted octahedral. TL glow curves were recorded with different heating rates (1, 2, 5, 10, 15, and 20∘C s−1) at the fixed dose 10 × 103 Gy. The results revealed that the glow peak position shifted to higher temperature with heating rate and the heating rate of 10∘C s−1 showed the superior TL response with highest glow peak which is very good for dosimetry purposes.

Morphology controlled syntheses of Cu-doped ZnO, tubular Zn(Cu)O and Ag decorated tubular Zn(Cu)O microcrystals for photocatalysis

Without any assistance of surfactant and/or template the hexagonal prism-shaped Cu2+-doped ZnO (Zn(Cu)O) microcrystals with twinned structures were easily synthesized by one-step co-precipitating under atmospheric pressure and moderate temperature, in which Cu2+ ion was used as the dopant and the morphology controller. Because Cu2+ ions can be adsorbed on the (0001) and {101¯1} planes the growth on these planes was restrained, resulting in the formation of Zn(Cu)O microcrystals with stubby hexagonal prism shape. Meanwhile, the twinned structure Zn(Cu)O microcrystals were obtained via the electrostatic interaction between adsorbed Cu2+ ion and two (0001¯) negative planes. When twinned structure Zn(Cu)O sample was etched by NaOH solution the (0001) polar planes at two ends of Zn(Cu)O crystal were dissolved via forming Zn(OH)42− complex ion, but the non-polar {0110} planes did not. As a result, the tubular structure Zn(Cu)O microcrystals (T-Zn(Cu)O) were obtained in the absence of template and/or specific protective agent. The metallic Ag decorated tubular Zn(Cu)O (T-Zn(Cu)O/Ag) samples were prepared by auto-catalyzed deposition reaction. The morphological, structural, photoluminescence, as well as photocatalytic properties of Zn(Cu)O, T-Zn(Cu)O and T-Zn(Cu)O/Ag samples were investigated and the results indicated that the Zn(Cu)O sample with a very small amount of doped Cu2+ ion showed higher photocatalytic activity than ZnO. Tubular structure Zn(Cu)O samples showed moderately enhanced photocatalytic activities compared to corresponding Zn(Cu)O samples. By decorating metallic Ag on the surfaces the T-Zn(Cu)O/Ag samples exhibited distinctly enhanced photocatalytic activities due to the contribution of Schottky barrier and intensive light absorption in Vis and NIR regions.

A facile synthesis and spectral characterization of Cu2+ doped CdO/ZnS nanocomposite

A facile two-step method is demonstrated for the preparation of Cu2+ doped CdO/ZnS nanocomposite. Systematic investigations like X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDS, transmission electron microscopy (TEM), FT-IR, electron paramagnetic resonance (EPR), optical absorption, photoluminescence (PL) and magnetic studies are carried out for the prepared material. From powder XRD, the nanocomposites are comprised for cubic phase of both CdO and ZnS in a close contact with each other. The ground state wave function of dopant ions has been estimated from EPR studies. Optical and EPR data confirm that doped Cu2+ions occupy rhombically distorted octahedral sites with the host material. Due to doping, band gap has been changed and blue shifts occurred in PL. Magnetic measurements indicate a possible ferromagnetic response, associated to the exchange interaction between local spin-polarized electrons of Cu2+ ions and conductive electrons.

Spectral characterizations of undoped and Cu2+doped CdO nanopowder

Undoped and Cu2+ doped CdO nanopowders were prepared by solid state reaction method with the aid of ultrasonic waves. The prepared samples were characterized by powder X-ray diffraction, Scanning Electron Microscope, optical absorption, photoluminescence, Electron Paramagnetic Resonance and FT-IR spectroscopy techniques. From powder XRD pattern the lattice cell parameters and average crystallite sizes were evaluated. SEM images gave the stone like morphologies in the prepared sample. Optical and EPR data confirmed that the doped Cu2+ ions enter in the host material as rhombically distorted octahedral site. Photoluminescence spectra of undoped and Cu2+ doped CdO exhibited a weak UV and a strong blue emission band at 418, 446nm and a weak UV and a strong blue-green emission band at 427, 481nm respectively under the excitation wavelength of 380nm. The CIE chromaticity coordinates were also calculated from emission spectrum for undoped and Cu2+ doped samples as (x=0.151, y=0.112) and (x=0.158, y=0.165) respectively. The presences of various functional groups related to metal oxide and organic molecular groups were identified in the FT-IR spectra.