Copper Telluride Research Articles

Facile preparation of carbon wrapped copper telluride nanowires as high performance anodes for sodium and lithium ion batteries

Uniform carbon wrapped copper telluride nanowires were successfully prepared by using an in situ conversion reaction. The length of these nanowires is up to several micrometers and the width is around 30–40 nm. The unique one dimensional structure and the presence of conformal carbon coating of copper telluride greatly accommodate the large volumetric changes during cycling, significantly increase the electrical conductivity and reduce charge transfer resistance. The copper telluride nanowires show promising performance in a lithium ion battery with a discharge capacity of 130.2 mA h g−1 at a high current density of 6.0 A g−1 (26.74 C) and a stable cycling performance of 673.3 mA h g−1 during the 60th cycle at 100 mA g−1. When evaluated as anode material for a sodium ion battery, the copper telluride nanowires deliver a reversible capacity of 68.1 mA h g−1 at 1.0 A g−1 (∼4.46 C) and have a high capacity retention of 177.5 mA h g−1 during the 500th cycle at 100 mA g−1.

Multifunctional Cu2-xTe Nanocubes Mediated Combination Therapy for Multi-Drug Resistant MDA MB 453.

Hypermethylated cancer populations are hard to treat due to their enhanced chemo-resistance, characterized by aberrant methylated DNA subunits. Herein, we report on invoking response from such a cancer lineage to chemotherapy utilizing multifunctional copper telluride (Cu2−XTe) nanocubes (NCs) as photothermal and photodynamic agents, leading to significant anticancer activity. The NCs additionally possessed photoacoustic and X-ray contrast imaging abilities that could serve in image-guided therapeutic studies.

Role of substrate in electrodeposited copper telluride thin films

Copper telluride thin films have been prepared on different substrates using an electrodeposition technique. Stylus profilometry has been carried out to find out thickness value of the deposited films. X-ray diffraction analysis revealed that the prepared films possess polycrystalline in nature. Film composition with surface morphology has been analyzed using an energy dispersive analysis by X-rays and scanning electron microscopy. Optical absorption analysis showed that the prepared films possess band gap value in the range between 2.02 and 2.26 eV. Value of refractive index, extinction coefficient, real and imaginary dielectric constants are estimated for films obtained on transparent substrates.

Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals.

Cu2–xTe nanocubes were used as starting seeds to access metal telluride nanocrystals by cation exchanges at room temperature. The coordination number of the entering cations was found to play an important role in dictating the reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e., with coordination number 4), such as Cd2+ or Hg2+, yielded monocrystalline CdTe or HgTe nanocrystals with Cu2–xTe/CdTe or Cu2–xTe/HgTe Janus-like heterostructures as intermediates. The formation of Janus-like architectures was attributed to the high diffusion rate of the relatively small tetrahedrally coordinated cations, which could rapidly diffuse in the Cu2–xTe NCs and nucleate the CdTe (or HgTe) phase in a preferred region of the host structure. Also, with both Cd2+ and Hg2+ ions the exchange led to wurtzite CdTe and HgTe phases rather than the more stable zinc-blende ones, indicating that the anion framework of the starting Cu2–xTe particles could be more easily deformed to match the anion framework of the metastable wurtzite structures. As hexagonal HgTe had never been reported to date, this represents another case of metastable new phases that can only be accessed by cation exchange. On the other hand, the exchanges involving octahedrally coordinated ions (i.e., with coordination number 6), such as Pb2+ or Sn2+, yielded rock-salt polycrystalline PbTe or SnTe nanocrystals with Cu2–xTe@PbTe or Cu2–xTe@SnTe core@shell architectures at the early stages of the exchange process. In this case, the octahedrally coordinated ions are probably too large to diffuse easily through the Cu2–xTe structure: their limited diffusion rate restricts their initial reaction to the surface of the nanocrystals, where cation exchange is initiated unselectively, leading to core@shell architectures. Interestingly, these heterostructures were found to be metastable as they evolved to stable Janus-like architectures if annealed at 200 °C under vacuum.

Preparation of Copper Telluride Films by Co-Reduction of Cu(I) and Te(IV) Ions in Choline Chloride: Ethylene Glycol Ionic Liquid

Cathodic processes of direct co-reduction of Cu+ and Te4+ ions on Pt electrode at 60°C were investigated using cyclic voltammetry and electrochemical impedance spectroscopy techniques. The ionic liquid as background electrolyte consisted of a mixture of choline chloride and ethylene glycol (ChCl-EG 1:2 mol ratio) in which 5–20 mM CuCl and 8 mM TeO2 were dissolved. The voltammograms exhibited the following successive cathodic processes: Cu2+/Cu+ reduction, Te underpotential deposition, simultaneous deposition of Cu metal and CuTe compound, and deposition of Te-rich CuTe compound at the most negative potentials (from −0.5 V to −0.8 V). Corresponding dissolution or oxidation peaks were recorded on the anodic branch. The voltammetric results were confirmed by electrochemical impedance spectra. Copper telluride films have been synthesized on platinum substrate via potentiostatic electrodeposition at 60°C. It was found from atomic force microscopy that CuTe film samples prepared from ChCl-EG + 5 mM CuCl + 8 mM TeO2 ionic liquid have high growth rates. The x-ray diffraction patterns of the deposited films from ChCl-EG + 10 mM CuCl + 8 mM TeO2 ionic liquid indicated the presence of a Cu2Te phase for film deposited at −0.7 V and a Cu0.656Te0.344 phase for film deposited at −0.6 V.

Studies of antimony telluride and copper telluride films electrodeposition from choline chloride containing ionic liquids

Cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the deposition of antimony telluride or copper telluride from ionic liquid consisting in mixture of choline chloride with oxalic acid. In addition, the cathodic process during copper telluride formation was studied in the mixture of choline chloride with ethylene glycol. The results indicate that the Pt electrode is first covered with a Te layer, and then the more negative polarisation leads to the deposition of SbxTey or CuxTey semiconductor compounds. Thin films were deposited on copper and carbon steel at 60–70°C and were characterised by scanning electron microscopy, energy X-ray dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Their stoichiometry depends on the bath composition and applied potential. EDS and XRD patterns indicate the possible synthesis of stoichiometric Sb2Te3 phase and Cu2Te, Cu5Te3, and Cu2.8Te2 phases, respectively, by controlling the ratio of ion concentrations in ionic liquid electrolytes and deposition potential.

Array of bis-quaternary ammonium surfactant tailored Cu(2−x)Te quantum dots with amended functional assets

Copper telluride [Cu(2−x)Te] nanoparticles stabilized by highly hydrophobic surfactants were synthesised and their structural, optical and electrical properties were examined.

Characterization of Raw and Decopperized Anode Slimes from a Chilean Refinery

This work characterizes raw and decopperized slimes, with the objective of identifying the phases in these two sub-products. The main phases in copper anodes are metallic copper, including CuO, which are present in free form or associated with the presence of copper selenide or tellurides (Cu2(Se,Te)) and several Cu-Pb-Sb-As-Bi oxides. During electrorefining, the impurities in the anode release and are not deposited in the cathode, part of them dissolving and concentrated in the electrolyte, and others form a raw anode slime that contains Au, Ag, Cu, As, Se, Te and PGM, depending on the composition of the anode. There are several recovery processes, most of which involve acid leaching in the first step to dissolve copper, whose product is decopperized anode slime. SEM analysis revealed that the mineralogical species present in the raw anode slime under study were mainly eucarite (CuAgSe), naumannite (Ag2Se), antimony arsenate (SbAsO4), and lead sulfate (PbSO4). In the case of decopperized slime, the particles were mainly composed of SbAsO4 (crystalline appearance), non-stoichiometric silver selenide (Ag(2−x)Se), and chlorargyrite (AgCl).

Nanowires as Building Blocks to Fabricate Flexible Thermoelectric Fabric: The Case of Copper Telluride Nanowires.

A general approach to fabricate nanowires based inorganic/organic composite flexible thermoelectric fabric using a simple and efficacious five-step vacuum filtration process is proposed. As an excellent example, the performance of freestanding flexible thermoelectric thin film using copper telluride nanowires/polyvinylidene fluoride (Cu1.75Te NWs/PVDF = 2:1) as building block is demonstrated. By burying the Cu1.75Te NWs into the PVDF polymer agent, the flexible fabric exhibits room-temperature Seebeck coefficient and electric conductivity of 9.6 μV/K and 2490 S/cm, respectively, resulting in a power factor of 23 μW/(mK(2)) that is comparable to the bulk counterpart. Furthermore, this NW-based flexible fabric can endure hundreds of cycles of bending tests without significant performance degradation.

High thermoelectric performance in copper telluride

Recently, Cu2-δS and Cu2-δSe were reported to have an ultralow thermal conductivity and high thermoelectric figure of merit zT. Thus, as a member of the copper chalcogenide group, Cu2-δTe is expected to possess superior zTs because Te is less ionic and heavy. However, the zT value is low in the Cu2Te sintered using spark plasma sintering, which is typically used to fabricate high-density bulk samples. In addition, the extra sintering processes may change the samples’ compositions as well as their physical properties, especially for Cu2Te, which has many stable and meta-stable phases as well as weaker ionic bonding between Cu and Te as compared with Cu2S and Cu2Se. In this study, high-density Cu2Te samples were obtained using direct annealing without a sintering process. In the absence of sintering processes, the samples’ compositions could be well controlled, leading to substantially reduced carrier concentrations that are close to the optimal value. The electrical transports were optimized, and the thermal conductivity was considerably reduced. The zT values were significantly improved—to 1.1 at 1000 K—which is nearly 100% improvement. Furthermore, this method saves substantial time and cost during the sample’s growth. The study demonstrates that Cu2-δX (X=S, Se and Te) is the only existing system to show high zTs in the series of compounds composed of three sequential primary group elements. A time-saving procedure for boosting the performance of experimental thermoelectric energy harvesters has been developed by a team in China. Recently, copper sulfide (CuS) and copper selenide (CuSe) compounds have garnered interest as thermoelectric generators because their extraordinarily low thermal conductivities enable highly efficient conversion of temperature swings into electricity. However, copper telluride (CuTe) compounds, which have even lower lattice thermal conductivities than CuS or CuSe compounds, have so far displayed only moderate thermoelectric capacities. Xun Shi at the Chinese Academy of Sciences and co-workers solved this mystery by eliminating the spark plasma sintering procedure normally used to produce high-density CuS and CuSe thermoelectrics. The researchers raised the thermoelectric efficiency by a few times by directly annealing CuTe crystals. They attribute this increase to better control over carrier concentrations in the samples’ crystal structure. Enhanced thermoelectric figure of merit in the fully densified Cu2Te bulk materials by direct annealing method.

Measurements of copper and cesium telluride cathodes in a radio-frequency photoinjector

Radio-frequency (rf) photoinjectors are commonly used to generate intense bright electron beams for a wide range of applications, most notably as drivers for X-ray Free-Electron Lasers. The photocathode, mounted inside an rf gun and illuminated by a suitable laser, thereby plays a crucial role as the source of the electrons. The intrinsic emittance and the quantum efficiency of the electron source are determined by the properties of the photocathode's surface material. We present measurements of the intrinsic emittance and the quantum efficiency performed with copper and cesium telluride cathodes in the same rf photoinjector, thus comparing, for the first time, the performance of metal and semiconductor cathodes under the same conditions. Our results are consistent with theoretical expectations and show that the difference in intrinsic emittance for the two types of material is not significant in view of accelerator applications. We conclude that cesium telluride photocathodes provide a much higher quantum efficiency at essentially negligible degradation in beam emittance.

Twin-Tail Surfactant Peculiarity in Superficial Fabrication of Semiconductor Quantum Dots: Toward Structural, Optical, and Electrical Features

A solitary tread hydrothermal synthesis of lead telluride (PbTe) and copper telluride (Cu(2–x)Te) nanoparticles (NPs) at 150 °C was carried out using cationic twin-tail surfactant (TTS) dimethylenebis(dodecyldimethylammonium bromide) (12-2-12) as a capping agent. UV–vis and X-ray diffraction (XRD) have been employed to elaborate about structural and physicochemical aspects of NPs. The morphology and the capping behavior have been revealed through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Electron micrographs clearly demonstrated the formation of cubic shaped PbTe NPs with average size distribution ≅ 20 ± 5 nm. A perversely spherical morphology has been observed for Cu(2–x)Te NPs with average size ≅15 ± 6 nm. The interactions of the adsorbed capping surfactant TTS on the metal surface and alignment of the molecules were confirmed from FTIR studies. The crystallite sizes and lattice strain on the peak broadening of the NP have been measured using Williamson–Hall analysis and the size–strain plot method. The optical band gap energy of NP, as determined from the absorbance spectrum, was 0.5 eV for lead telluride, while that for copper telluride was 3.4 eV owing to quantum confinement driven shift from bulk materials to nanoscale. The electrical conductivity of lead telluride and copper telluride was found to be 0.01–0.07 and 2.18–10.1 S cm–1, respectively.

Effects of chemical intermixing on electrical and thermal contact conductances at metallized bismuth and antimony telluride interfaces

Tailoring electrical and thermal contact conductivities (Σc and Γc) across metallized pnictogen chalcogenide interfaces is key for realizing efficient thermoelectric devices. The authors report that Cu, Ni, Ti, and Ta diffusion and interfacial telluride formation with n-Bi2Te3 and p-Sb2Te3 influence both Σc and Γc. Cu metallization yields the highest Γc and the lowest Σc, correlating with maximal metal diffusion and copper telluride formation. Ni diffuses less and yields the highest Σc with Sb2Te3 due to p-type nickel telluride formation, which diminishes Σc improvement with n-Bi2Te3 interfaces. Ta and Ti contacts yield the lowest properties similar to that in Ni-metallized structures. These correlations between interfacial diffusion and phase formation on electronic and thermal transport properties will be important for devising suitable metallization for thermoelectric devices.

TWINNING AND DISORDER IN THE CRYSTAL STRUCTURE OF KURILITE, Ag8Te3Se: TOWARD A NEW FAST IONIC CONDUCTOR?

The crystal structure of the mineral kurilite, a rare silver chalcogenide, was solved using intensity data collected from a twinned crystal of type material from the Prasolovskoe deposit, Kunashir Island, Kuril islands (Russia). The study revealed that the structure is trigonal, space group R ![Formula][1] , with cell parameters: a 15.8135(18), c 19.618(3) A, and V 4248.6(9) A3. The refinement had a final R index of 0.0218 for 2513 observed reflections [ I > 2σ( I )] and 0.0265 for all 2776 independent reflections and 193 parameters. Three Te sites, three Se sites, and ten Ag sites occur in the crystal structure of kurilite. The silver cations form various crystal-chemical environments, as is typical of many intermetallic compounds. The Ag positions correspond to the most pronounced probability density function ( pdf ) locations (modes) of diffusion-like paths. The d 10 silver ion distribution was determined by means of a Gram-Charlier development of the atomic displacement factors. Crystal-chemical features are discussed in relation to other copper and silver tellurides and pure metals. The disorder observed for the Ag atoms is compared to that of other natural fast ionic conductors, such as the pearceite-polybasite group minerals. On the basis of information gained from the structural characterization, the Z of the crystal-chemical formula was revised to 18 instead of 15, as previously reported. [1]: /embed/mml-math-1.gif

Metallic Binary Copper Chalcogenides with Orthorhombic Layered Structure

ABSTRACTChalcogenide materials have regained attention after the recent recognition of the compatibility of transition metal dichalcogenides with graphene. Additionally, there has been a recent appreciation for the rich variety of properties they support due to the anomalies in the materials’ intrinsic band structure. These materials generally have layered structures and weak interlayer connection through the chalcogen layer and its van der Waals type bonding. We have synthesized orthorhombic copper telluride and measured its electrical transport properties. The results of these measurements reveal that the conduction is metallic in both the in-plane and out-of-plane directions. The range of stability of this structure is examined along with the lattice constants. The independence of the resistivity in samples to changes in excess copper indicates that the transport is essentially within the conducting planes. This result shows that the material hosts two-dimensional character likely due to its covalent interlayer bonding.

Cu6Te3S – a Cu-filled Cr3Si-structure variant

Abstract A solid state melting and annealing route was used to prepare Cu6Te3S, a copper telluride sulfide representing a filled variant of the Cr3Si structure type. The title compound exhibits a reversible phase transition at 404 K which was confirmed by thermal analysis, temperature dependent X-ray single crystal and powder diffractometry. Both polymorphs crystalize cubic in space groups P 4 ¯ 3 n $P\bar 43n$ and P213, respectively. X-ray photoelectron spectroscopy (XPS) was performed to evaluate the electronic structure of Cu6Te3S and to determine the oxidation state of Cu in the title compound.

Shape-controlled synthesis of copper telluride micro/nanostructures via a simple electrochemical deposition route

Shape-controllable synthesis of copper telluride micro/nanostructures has been successfully realized in air at room temperature by a simple galvanostatic electrodeposition route. By tuning experimental parameters such as the original Cu and Te sources, additives, deposition currents and media, copper telluride micro/nanostructures with various morphologies, including nanorod arrays, nanosphere-strewn copper telluride dendrites, copper telluride nanowires and star-like hexagonal copper telluride dendrites, were rapidly deposited in air at room temperature for 5 min. The final products were characterized by various means including X-ray diffraction, scanning electron microscopy, (high-resolution) transmission electron microscopy, and energy-dispersive spectrometry. The mechanisms of copper telluride production in various media are discussed.

Synthesis of cauliflower like shapes of copper telluride by electron beam irradiation

In this work we employed electron irradiation technique to prepare copper telluride nanostructures with various dimensions by irradiating electrodeposited thin films. The irradiation dose could be used to control the diameter of the electrodeposited copper telluride nanostructures within the range of nanometer scale. This study reports the effect of irradiation of 2 MeV electron beam on the structural, surface morphological, and optical properties of copper telluride thin films. The band gap energy decreases from 2.82 to 2.53 eV with increase in crystal size from 9 to 45 nm with an increase in the dose from 10 to 30 kGy. X-ray diffraction studies show that crystal size decreases from 9 to 6 nm with a dose of 50 kGy. The fluence of the electron beam was 2 × 1013 electrons/cm2. The crystal size was found to decrease upon electron beam irradiation and the materials exhibit poor crystallization.

Controlled synthesis of copper telluride nanostructures for long-cycling anodes in lithium ion batteries

Copper telluride nanocubes, nanosheets, and nanoparticles were prepared by a solvothermal method under the protection of an inert atmosphere. The influence of reaction parameters, including precursor concentration, precursor ratio, precursor type, reaction time, reaction temperature, solvent, and organic ligands, on the size, morphology, crystalline structure, and composition of the resultant copper telluride nanostructures was comprehensively investigated. The results showed that the crystal structure and composition of the resultant nanostructures varied case by case, demonstrating the complexity of copper tellurides, despite their simple molecular formula. The obtained copper telluride nanostructures were tested as anodes in lithium ion batteries. The assembled Li/LiPF6/CuxTe cells exhibit extremely high cycling stability (up to 5000 cycles) and their highest specific capacity is 280 mA h g−1. The results also showed better performance of the Cu2−xTe nanosheet electrodes than those of electrodes made from nanoparticles and nanocubes, demonstrating the importance of controlling the morphology of copper telluride during preparation.

CAMERONITE, Cu5−x(Cu,Ag)3+xTe10(x= 0.43), FROM THE GOOD HOPE MINE, VULCAN, COLORADO: CRYSTAL STRUCTURE AND REVISION OF THE CHEMICAL FORMULA

The crystal structure of the mineral cameronite, a rare copper-silver telluride, was solved using intensity data collected from a crystal of the holotype material from the Good Hope mine, Vulcan, Colorado (USA). The study revealed that the structure is monoclinic, space group C 2/ c , with cell parameters: a 17.906(1), b 17.927(1), c 21.230(2) A, β 98.081(8)°, and V 6747.2(8) A 3 . The refinement of an anisotropic model led to an R index of 0.0216 for 9688 independent reflections. Nineteen Te sites and 14 metal (M) sites occur in the crystal structure of cameronite. Six M sites host Cu with variable amounts of Ag, whereas the remaining eight M sites host Cu only. All of the atoms are in tetrahedral coordination and complex MTe 4 , M(Te 3 M), M(Te 2 M 2 ), TeM 4 , Te(M 3 Te), Te(M 2 Te 2 ), Te(MTe 3 ), and TeTe 4 crystal-chemical environments are formed, as is typical of many intermetallic compounds. The short bond distances observed mainly among the Te atoms are discussed in relation to other copper and silver tellurides and pure metals. Electron microprobe analyses of the crystal used for the structural study led to the formula Cu 7.08 Ag 1.06 Fe 0.01 S 0.01 Te 9.84 , on the basis of 18 atoms. On the basis of information gained from the structural and chemical characterization, the crystal-chemical formula was revised, yielding Cu 5− x (Cu,Ag) 3+ x Te 10 ( Z 14) with x = 0.43 instead of Cu 7 AgTe 10 ( Z 16) as previously reported.