Cu-Te Alloys Research Articles

Properties and microstructure characterisation of high-strength, high-conductivity and high-resistance to arc ablation Cu-0.6Te-0.3Cr-0.15Zr-0.008P alloy

In this paper, the intermetallic compound ZrTe2 phase is formed within a copper matrix by data-driven elemental screening. This low melting point ZrTe2 phase is uniformly and diffusely distributed within the copper matrix, which avoids the need for an energy-intensive process while providing superior resistance to arc ablation. On this basis, a novel Cu-0.6Te-0.3Cr-0.15Zr-0.008P alloy is designed and prepared, and the alloy achieves an electrical conductivity of 95.7 %IACS, a tensile strength of 302 MPa, and an elongation of 39.53% after the thermomechanical treatment. The ablation current of the novel alloy under large voltage is 31.2% lower than that of the Cu-0.6Te alloy, and the cross-sectional area of the ablation traces is reduced by 85%, which effectively illustrates the substantial improvement of the novel alloy's ability to resist arc ablation. There are ZrTe2 phases of 0.5–2 μm as well as pure Cr phases of about 5–20 nm in the alloy. The ZrTe2 phases absorbs heat through melting decomposition to achieve arc extinction, and the Cr phases pinning dislocations to promote strength enhancement. In addition, the synergistic addition of Cr and Zr plays a role in the grain refinement of the alloy, and the average size of the grains decreases from 4.2 μm to 3.1 μm, a decrease of 26%, under the same process. This novel CuTe alloy with high strength, high conductivity and high resistance to arc abrasion is easy to produce and low energy consumption, and is expected to be widely used in the new generation of high-voltage fast-charging electrical connector materials for new energy vehicles.

Quantitative mechanisms behind the high strength and electrical conductivity of Cu-Te alloy manufactured by continuous extrusion

The microstructure, mechanical performance, and electrical conductivity of Cu-Te alloy fabricated by continuous extrusion were quantitatively investigated. The results demonstrate that the grain size of the Cu-Te alloy is refined significantly by incomplete dynamic recrystallization. The Cu2Te phase stimulates recrystallization and inhibits subgrain growth. After extrusion, the tensile strength increases from 217.8 ± 4.8 MPa to 242.5 ± 3.7 MPa, the yield strength increases from 65.1 ± 3.5 MPa to 104.3 ± 3.8 MPa, and the yield to tensile strength ratio is improved from 0.293 ± 0.015 to 0.43 ±.0.091, while the electrical conductivity of room temperature decreases from 95.8 ± 0.38% International Annealed Cu Standard (IACS) to 94.0% ± 0.32% IACS. The quantitative analysis shows that the increment caused by dislocation strengthening and boundary strengthening account for 84.6% of the yield strength of the extruded Cu-Te alloy and the electrical resistivity induced by grain boundaries and dislocations accounts for 1.6% of the electrical resistivity of the extruded Cu-Te alloy. Dislocations and boundaries contribute greatly to the increase of yield strength, but less to the increase of electrical resistivity.

Electrochemical sensing of copper employing tellurium film electrode

An ASV procedure featuring a new tellurium film electrode deposited in-situ on a glassy carbon substrate in 0.1M HCl is presented. The electrochemical behavior of the tellurium film electrode with regard to its applicability in the ASV determination of copper(II) was thoroughly studied and discussed. It was found that during the accumulation step in 0.1M HCl, Cu(II) is co-deposited with tellurium at − 0.5V in the form of a Cu-Te alloy. When SW-ASV is used, Cu(II) accumulated in-situ with Te(IV) on the GC electrode yields a stripping peak at a potential ca. 240mV more positive than that obtained at a bare GC; this peak is also 3.65 times higher. The key parameter that determines the performance of the TeF/GC electrode in the ASV determination of Cu(II) is the concentration of Te(IV) present in the supporting electrolyte. For higher concentrations of Cu(II) in the range from 25 to 125μgL−1 and a time of accumulation equal to 60s, the Te(IV) concentration of 150μgL−1 is recommended. In the Cu(II) concentration range from 0.5 to 25μgL−1 and a longer accumulation time of 300s, 50μgL−1 of Te(IV) is optimal. These conditions allow a relatively positive potential window to be applied and, consequently, make the TeF/GC electrode a viable alternative to the BiFE and SbFE in the determination of Cu(II) traces via anodic stripping voltammetry. The application of the tellurium film electrode under the optimized conditions (supporting electrolyte containing 0.1M HCl and 50μgL−1 Te(IV), 300s of accumulation at −0.5V, square wave voltammetric mode) assures a sensitive stripping voltammetric response for Cu within the concentration range of 0.5 to 25μgL−1, good precision (RSD=4%), and a low detection limit (0.18μgL−1 Cu). Possible interferences from the co-existing ions and surface-active substance were investigated. The proposed method of copper determination was successfully applied and validated with the use of mineral water sample.

Multi-Level CuO-Based Conductive-Bridging-Random-Access-Memory Cell Embedded with Au Ncs

Recently, memory industry has demanded terabit-level memory cell of high density to have bit cost-competition. However, current memory technology such as DRAM and NAND flash memory has a physical limit due to their charge-storage system. Conductive bridging random access memory (CBRAM) is considering as one of the promising candidate for next generation non-volatile memory (NVM) because it has many advantages such as low power consumption, and large on/off ratio. In particular, CBRAM has a possibility of terra-bit-level nonvolatile memory as a post flash memory due to their 4F2simple structure of a top reactive electrode, electrolyte, and bottom inert electrode, and they showed a bipolar switching memory characteristic.[1] We have developed a nanoscale CBRAM cell with a structure of TiN/CuO/Ag/TiN. It showed good nonvolatile memory performance such as as a ~1.23 X 102 memory margin (Ion/Ioff), ~3 X 106 AC set/reset endurance cycles by with 100-μs AC pulse width by sustaining a 1.31 X 102 memory margin, ~6.63-years retention time at 85 °C by sustaining a 3.63 X 102 memory margin, 100 ns program speed, and multi-level (four level) cell operation.[2] However, for achieving commercial-level non-volatile memory cell, the CBRAM cell with Ag or Cu electrode has some problem such as poor stability and reliability due to undesired diffusion of Ag and Cu ions in solid-electrolyte. Thus, the undesired diffusion of Ag and Cu ions leads to the formation of multiple and thick filaments resulting in degradation of write/erase endurance cycles. To solve this issue, we applied Cu-Te alloy electrode for CuO solid-electrolyte-based CBRAM cell. Also, to enhance the nonvolatile memory characteristics of the CBRAM cell, Au nano-crystals (NCs) were intentionally inserted between the CuO solid electrolyte and TiN bottom electrode, where the Au NCs were created by depositing Au thin-film via thermal evaporation. Thus, the Au NCs inserted in CBRAM cell made intensive fields be formed on Au NCs and then localized Cu-ion bridging filaments could be formed on Au NCs deposited in solid electrolyte earlier than on TiN bottom electrode. Since it was well-known that the CBRAM was operated by metal-filaments formed in solid electrolyte, well-controlled metal-filaments could be a key factor of nonvolatile memory characteristics. Therefore, inserting the Au NCs in the CBRAM cell could enhance the nonvolatile memory characteristics and reduce the forming voltage of CBRAM cell due to controlling the random position and orientation of Cu-ion bridging filaments. The CBRAM cell embedded with proper Au NCs exhibited the enhanced nonvolatile memory characteristics such as AC set/reset endurance cycles of 1.0 X 107, read endurance cycles of 1.0 X 1010, and retention time at 85 oC of ~16 years. Moreover, the multi-level cell operation of the CBRAM cell embedded with proper Au NCs also was obtained with improved AC set/reset endurance cycles of 1.0 X 105, and retention time of 1.0 X 105sec. * This work was financially supported by the Industrial Strategic Technology Development Program (10039191, The Next Generation MLC PRAM, 3D ReRAM, Device, Materials and Micro Fabrication Technology Development) funded by the Ministry of Trade, Industry and Energy (MOTIE), Republic of Korea and the Brain Korea 21 Plus, Republic of Korea. Figure 1

4.7-THz Superconducting Hot Electron Bolometer Waveguide Mixer

We present the first superconducting hot electron bolometer (HEB) waveguide mixer operating at 4.7 THz. The 5.5-nm-thick, 300-nm-long, and 3600-nm-wide NbN HEB microbridge is integrated into a normal metal (Au) planar circuit on a 2 $\mu$ m thick silicon substrate. This circuit is integrated in a 24 $\mu$ m $\,\times\,$ 48 $\mu$ m $\,\times\,$ 21 $\mu$ m waveguide cavity and a 14 $\mu$ m $\, \times \,$ 7 $\mu$ m $\, \times \,$ 200 $\mu$ m substrate channel, which is directly machined into a CuTe alloy block. The power spectrum of the HEB mixer, measured with a Fourier transform spectrometer, is in good agreement with the results of 3-D EM circuit simulation. Measured mixer performance shows a state-of-the-art double sideband noise temperature of 1100 K, averaged over the IF bandwidth of 0.2–3.5 GHz. The 3-dB noise roll-off is 3.5 GHz. This mixer is used in the German REceiver for Astronomy at Terahertz frequencies (GREAT) at the airborne Stratospheric Observatory for Far Infrared Astronomy (SOFIA).

Effects of annealing temperature on the electrical conductivity and mechanical property of Cu-Te alloys

The effects of annealing temperatre on the electrical conducitivity and mechanical property of Cu-Te alloys were studied via an AG-10TA electronic universal machine, an SB2230 digital electric bridge, SEM, EDS and XPS. The results show the electrical conductivity increases while the tensile strength fluctuates when the annealing temperature becomes higher because the recrystallization occurs during the annealing process, leading to the density of dislocation decreasing, grain size growing up, but the second phase precipitating sufficiently and simultaneously.

Effects of annealing process on electrical conductivity and mechanical property of Cu-Te alloys

The effects of annealing process on the electrical conductivity and mechanical properties of Cu-Te alloys were studied via AG-10TA electronic universal machine, SB2230 digital electric bridge, SEM and EDS. The results show that recrystallization and precipitation occur simultaneously during the annealing process of Cu-Te alloys. Tellurium precipitates as Cu 2Te second phase. The grain size increases with the increasing of annealing temperature and time. The electrical conductivity increases monotonously. The tensile strength of Cu-Te alloy is higher than that of pure copper.

Thermal dissociation of copper chalcogenides during melting

An attempt was undertaken to describe the mechanism of dissociation of copper chalcogenides during melting. Two-stage schemes of the dissociation of the Cu 2 B VI compounds (B VI is S, Se, or Te) were proposed. It was suggested that in the copper-sulfur and copper-selenium melts, Cu2BVI and CuBVI associates exist, whereas in the copper tellurium systems, Cu 2 Te and Cu 5 Te 3 associates exist. The interpretation of available data on magnetic susceptibility was given in terms of suggested associates in Cu-Te alloys.

Wire fixation for proportional and drift chambers using a Cu-Te alloy

Using a Cu-Te alloy we have developed a simple and reliable method to fix and electrically connect wires in drift and proportional chambers. The method lends itself to mass production and has been employed in two detector systems: The endcap hadron calorimeter proportional tube chambers of the L3 experiment and the L3 forward/backward muon drift chambers.

Chemical Vapor Deposition of Copper Alloys

ABSTRACTChemical vapor deposition of metals is becoming a desirable alternative to physical deposition techniques (e.g. sputtering, evaporation) for applications in chip wiring. This is due to the possibility of achieving highly conformal coverage and low processing temperatures. Additionally, it is convenient to be able to enhance the physical properties (e.g. corrosion resistance, adhesion, electromigration resistance) of metal films used for chip interconnection by incorporation of an alloying agent. We have investigated the possibility of extending our current copper deposition process to allow for the deposition of copper alloys. By careful selection of the precursors and reactor conditions, simultaneous decomposition of the two compounds to give clean alloy films is effected. Using this co-deposition method, Cu-Co and Cu-Te alloy films were prepared. Precursor and reaction chemistry are discussed as well as some properties of the resulting films.

Thermodynamic properties of the ternary Na–Cu–Te alloy by electromotive force measurements with an alumina solid electrolyte

Activity coefficients for sodium metal in the equimolar CuTe alloy were measured up to 54 at. % sodium at 913 K. The experimental technique consisted of an alloy concentration cell with a solid alumina electrolyte. The results indicated that the solutions were Henrian up to 1 at. % sodium. In addition, for dilute sodium concentrations, there is an exosolution effect. However, for the more concentrated solutions, there is some ionicity. Keywords: tellurides, thermodynamics, alkali metals.

The X-ray diffraction study of deformations in the copper matrix of Cu-Te alloys

Detailed studies considering the recent developments in the analysis of line shift, line asymmetry and Fourier lineshape have been made on the X-ray diffraction profiles pertaining to the pure copper phase in the composite matrix of Cu and Cu2Te (hexagonal) phases in Cu-Te alloys with solute tellurium at 3.30, 5.62, 12.02 and 13.08 wt.%. The microstructural parameters such as the coherent domain sizes, the microstrains within the domains, the intrinsic fault density, alpha ', the extrinsic fault density, alpha " and deformation twin fault density, beta , have been evaluated. While the intrinsic fault density, alpha ', and the extrinsic fault density, alpha ", were found to be absent even at higher solute contents, the deformation twin fault density, beta , which is normally absent in Cu and Cu-base alloy systems, is found to be present here in an appreciable quantity. The reason for the presence of this deformation twin fault in the Cu phase may be attributed to the influence of a neighbouring Cu2Te phase in the matrix.

The electronic structure of glassy and crystalline Cu-Te alloys

The electronic structure of glassy and crystalline CuxTe1-x (0<or=x<or=0.58) alloys has been investigated with ultraviolet photo-electron spectroscopy (UPS). X-ray diffraction, differential scanning calorimetry (DSC) and X-ray photo-electron spectroscopy (XPS) have been used to characterise the samples. The UPS data indicate a metal-to-semiconductor transition near x=0.45.

溶銅中への硫黄, セレン, テルルの相互拡散

Chemical inter-diffusion coefficients of sulfur, selenium, and tellurium in liquid copper have been measured with the modified capillary reservoir method in the temperature range from 1, 100°to 1, 300°C. Several liquid Cu-S Cu-Se, and Cu-Te alloys ranging in composition from 0.2 to 0.8 wt% S, from 0.5 to 3. 0 wt% Se, and 5.0 wt%Te were used as the liquid alloys for reservoir. From the re-examination of the applicability of simplified equations for the calculation of diffusion coefficient, it was found that the equation derived by Derge et. al. can only be used when the ratio ofCa/Cs, ratio between the average concentration of sample-Caand the concentration of reservoir liquid Cs, is less than 0.6 or, θ(=π2Dt/4l2)<0.7. Experimental error due to the chemical analysis of sample increases with the decreasing ratio ofCa/Cs. To obtain accuratediffusion coefficients by the use of this simplified equation, the experimental condition should be controlled so that the ratio ofCa/Csis in the range from 0.4 to 0.6. Results obtained are summerized as follows:1) The diffusion data fit the following Arrhenius type equations; for sulfurDc=2.0×10-2exp (-14, 500/RT) cm2/secQ=14.5±1.4kcal/molefor seleniumDc=4.0×10-3exp (-11, 900/RT) cm2/secQ=11.9±1.6kcal/molefor telluriumDc=3.4×10-3exp (-12, 800/RT) cm2/secQ=12.8±2.3kcal/mole2) The diffusivity increases (DS>DSe>DTe) with the decreasing radius of diffusing particle (rs<rse<rTe).