Evolution Of Electrical Resistivity Research Articles

Temperature driven evolution of thermal, electrical, and optical properties of Ti–Al–N coatings

Monolithic single phase cubic (c) Ti1−xAlxN thin films are used in various industrial applications due to their high thermal stability, which beneficially effects lifetime and performance of cutting and milling tools, but also find increasing utilization in electronic and optical devices. The present study elucidates the temperature-driven evolution of heat conductivity, electrical resistivity and optical reflectance from room temperature up to 1400°C and links them to structural and chemical changes in Ti1−xAlxN coatings. It is shown that various decomposition phenomena, involving recovery and spinodal decomposition (known to account for the age hardening phenomenon in c-Ti1−xAlxN), as well as the cubic to wurtzite phase transformation of spinodally formed AlN-enriched domains, effectively increase the thermal conductivity of the coatings from ∼3.8Wm−1K−1 by a factor of three, while the electrical resistivity is reduced by one order of magnitude. A change in the coating color from metallic grey after deposition to reddish-golden after annealing to 1400°C is related to the film structure and discussed in terms of film reflectivity.

On electrical resistivity evolution of Sn–Sb10 melt during isothermal processes at different temperatures

To study the melt structural evolution, at different temperatures, electrical resistivity evolution patterns with the time of Sn–Sb10 melt were experimentally investigated during isothermal processes. There was no change in resistivity during the isothermal process at 850°C for 360 min, while at higher temperatures, i.e. 875°C, 885°C, and 900°C, there was a dropping turn in the resistivity-time curves at different ranges. The higher the isothermal temperature, the earlier the dropping turn and the shorter the time range. As the resistivity resort was verified to be sensitive and valid for investigating liquid structure changes in past studies, the resistivity turn suggests the occurrence of a temperature-induced liquid structure transition. Based on the results, the kinetic mechanism of the liquid transition was also studied and the activation energies of the transition were calculated too.

Modeling of Electrical Resistivity Evolution Using Free Energy Analysis for NiTi Shape Memory Alloy Wires

This paper presents a transformation kinetics model of NiTi shape memory alloy (SMA) wires based on electrical resistivity (ER) derivative study under the assumption that the derivative of electrical resistivity with respect to temperature is in linear relationship with the derivative of free energy change with respect to temperature. Free energy change and electrical resistivity properties of SMA are analyzed based on differential scanning calorimetry (DSC) experiments during phase transformation. The simulated evolution of electrical resistivity during thermomechanical transformation is presented using the proposed model.

Electrical properties of electroplated Cu(Ag) thin films

To increase the electromigration resistance of copper interconnects copper alloy systems are of interest. In the present paper electrical properties of Cu(Ag) films will be discussed with respect to heat treatment and in comparison to copper and other alloy systems. The investigations show that the electrical resistivity of Cu(Ag) films is very low in comparison to other copper alloy systems. Up to an alloy content of about 2 at.% Ag the International Technology Roadmap for Semiconductors criterion of 2.2 μΩcm (scattering by geometrical constraints neglected) can be fulfilled after heat treatment. The various components of the electrical resistivity will be discussed in detail. The investigations show that grain growth and the redistribution of silver and impurities dominate the electrical resistivity evolution.

Electrical resistivity evolution in the annealed amorphous Fe 78Si 9B 13 ribbons

The electrical resistivity was measured at room temperature for the amorphous Fe 78Si 9B 13 ribbons annealed at various temperatures for different holding time. Although the annealed Fe 78Si 9B 13 ribbons are in full amorphous state, their electrical resistivity obviously varies with the annealing time. At every annealed temperature, the electrical resistivity evolution can be divided into regions I, II, and III, respectively. Using X-ray diffraction (XRD), scanning electron microscope (SEM), and differential scanning calorimetry (DSC), we investigated the ribbons overlapping regions I and II (called the focused ribbons, FRs). The results show that the change of electrical resistivity, fracture morphology, thermal effect in DSC analysis of the focused ribbons (FRs) can be ascribed to the evolution of the short range order (SRO) in the amorphous alloy.

Using cluster dynamics to model electrical resistivity measurements in precipitating AlSc alloys

Electrical resistivity evolution during precipitation in AlSc alloys is modeled using cluster dynamics. This mesoscopic modeling has already been shown to correctly predict the time evolution of the precipitate size distribution. In this work, we show that it leads too to resistivity predictions in quantitative agreement with experimental data. We only assume that all clusters contribute to the resistivity and that each cluster contribution is proportional to its area. One interesting result is that the resistivity excess observed during coarsening mainly arises from large clusters and not really from the solid solution. As a consequence, one cannot assume that resistivity asymptotic behavior obeys a simple power law as predicted by LSW theory for the solid solution supersaturation. This forbids any derivation of the precipitate interface free energy or of the solute diffusion coefficient from resistivity experimental data in a phase-separating system like AlSc supersaturated alloys.

Pecularities of electrical resistivity during transformations in amorphous and nanocrystalline alloys

Classical transformations from rapidly quenched amorphous into (nano)crystalline state monitored by time and temperature evolution of electrical resistivity are discussed as a typical case. Common and different features observed in these transformations, related to local structural and chemical arrangements, are compared with special cases, e.g. sharp increase of resistivity during energy-intensive crystallization observed in Fe–Ni based amorphous systems. A drastic increase of electrical resistivity during transformation in Al–V system is attributed to the formation of nanoquasicrystalline structures with a predicted pseudogap in the electron density at the Fermi level. The results are correlated with microstructure observations and with data from routinely used methods of kinetic analysis with respect to the expected local atomic ordering in amorphous precursor systems.

Examination of precipitation in the aluminum alloy AA6111 using electrical resistivity measurements

The evolution of electrical resistivity during the aging of aluminum alloy AA6111 has been measured over a wide range of annealing temperatures. From these measurements, the solubility product for the Q phase in aluminum has been proposed and using a new approach, the contribution of precipitates to the overall resistivity is quantified.

Evolution of microstructure and electrical resistivity of Cu?12wt.%Ag filamentary microcomposite with drawing deformation

Abstract Cu–12wt.%Ag filamentary microcomposite was prepared by heavy cold drawing. The microstructure was observed and the electrical resistivity determined at different strain levels. The mechanism responsible for the electronic conduction was discussed according to the microstructure evolution during drawing deformation.

Equilibrium solid solubility of silicon in silver

The equilibrium solubility of silicon in silver was measured in the range between 300 °C and the eutectic temperature using both an electron microprobe and the evolution of electrical resistivity of a near-eutectic Ag-4 wt pct Si alloy. The silver matrix was found to dissolve up to 0.93 at. pct Si, at 836 °C. The resistivity was found to increase on average by 4.31 µΩcm/at. pct solute content of Si in the silver matrix. The solubility of silicon in silver is well described by an Arrhenius-type equation, with an apparent enthalpy of mixing of 74.7 kJ/mol and a prefactor of 30.6 (3060 at. pct). This finite terminal solubility of silicon in silver can account for a discrepancy between the calculated and experimental silver-silicon binary-phase diagrams, as present in the literature.

Effect of processing on electrical resistivity of textile fibers

Most test methods used to evaluate the electrostatic properties of textile materials are based, in one way or another, on the measurement of electrical resistance. Many and various methods have been devised to measure electrical resistance of textile assemblies and a diversity of parameters are used to define it. Generally speaking, it is very difficult to match results of different methods. In this paper we use, for measuring electrical resistivity of textile assemblies, a multiple-step method, which takes compressional properties of the assembly into consideration and defines a new parameter to describe electrical resistivity of textile assemblies. The new definition used for the resistivity of the textile assembly is similar to the volume resistivity of a rigid homogeneous material, being so an inherent characteristic reflecting electrical properties of fiber material, independent of sample form (fabric, yarn, fiber), dimensions of measuring cell and amount of the sample. This method made possible, for the first time, a measurement of the evolution of electrical resistivity of cotton and wool fibers during the spinning process. The results enabled the evolution of electrostatic properties of fibers to be determined as the they passed from one processing machine to the other. Thus, the intensity of processing and need for treatment with antistatic lubricants could be assessed.

Electrical-resistivity evolution in Fe 73.5Cu 1Nb 3Si 13.5B 9 during the amorphous-to-nanocrystalline transformation

Measurements of the electrical resistivity of Fe 73.5Cu 1Nb 3Si 13.5B 9 have been performed under isothermal and tempering conditions by means of a four-probe dc technique. The resistivity vs. temperature curves display a broad, shallow dip at temperatures where a nanosized crystalline phase appears. There, the isothermal resistivity relaxation does not obey any simple kinetic law. The onset of the development of boride phases corresponds to a definite drop of the isothermal resistivity. These results are supported by X-ray diffraction data and magnetic permeability measurements.

Some properties of hydrogenated amorphous silicon produced by direct reaction of silicon and hydrogen atoms

Abstract Measurements of electrical resistivity, optical absorption, photoconductivity, photoluminescence and hydrogen evolution indicate that a method of preparing hydrogenated amorphous silicon by a direct reaction of silicon vapour and atomic hydrogen produces material with good mechanical and electronic properties. The method also allows one to study the kinetics of synthesis and to test the effect of hydrogen incorporation on the disorder of the system.

Evolution of electrical resistivity for graphite-H2SO4 and graphite- sulphuric oleum compounds

Abstract Sulphuric intercalation compounds have been synthesized by means of galvanostatic anodic oxidation, using high quality, well oriented, HOPG-type graphite (p ≅ 40 μΩ-cm) and varying the molar ratio [SO3]/[H2O] of the electrolyte from 0.51 (aqueous H2SO4, 85%) to 1.22 (oleum, 15% free SO3). Voltammetry studies show the so-called “overoxidation” phenomenon, which may occur concurrently with the formation of the first stage compound, especially in the presence of an excess of H2O. The electrical resistivity of the first stage compounds has been studied from 100 to 300 K. Sharp transitions have been found, the temperatures of which are in a narrow range centred around 190 K. Hysteresis is evident for some compositions and is reproducible upon cycling.