Simultaneous Resistance Measurements Research Articles

Low-frequency resistance fluctuations in metal films under current stressing at low temperature(T<0.3Tmelting)

In this paper, we report a systematic study of low frequency $1∕{f}^{\ensuremath{\alpha}}$ resistance fluctuation in thin metal films (Ag on Si) at different stages of damage process when the film is subjected to high current stressing. The resistance fluctuation (noise) measurement was carried out in situ using a small ac bias that has been mixed with the dc stressing current. The experiment has been carried out as a function of temperature in the range of $150--350\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The experiment establishes that the current stressed film, as it undergoes damage due to various migration forces, develops an additional low-frequency noise spectral power that does not have the usual $1∕f$ spectral shape. The magnitude of extra term has an activated temperature dependence (activation energy of $\ensuremath{\approx}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$) and has a $1∕{f}^{1.5}$ spectral dependence. The activation energy is the same as seen from the temperature dependence of the lifetime of the film. The extra $1∕{f}^{1.5}$ spectral power changes the spectral shape of the noise power as the damage process progress. The extra term likely arising from diffusion starts in the early stage of the migration process during current stressing and is noticeable much before any change can be detected in simultaneous resistance measurements. The experiment carried out over a large temperature range establish a strong correlation between the evolution of the migration process in a current stressed film and the low-frequency noise component that is not a $1∕f$ noise.

Automatic Apparatus for Simultaneous Measurement of Resistance and Inductance Temperature Transition Dependences of Superconductors

An automatic measurement complex for the study of transition properties of HTc superconductors using the transport method of the measurement of the resistance temperature dependence and the contactless mutual inductance method of the measurement of temperature dependence of the induced voltage based on the Meissner-Ochsenfeld effect have been developed. In addition, temperature dependences of harmonic components of the induced voltage may be measured simultaneously using the Bruel & Kjaer signal analyzer. Results of transport and induced voltage measurements are compared using YBCO superconductors with distinct grain and intergrain properties prepared by different technological procedures. The question of the mutual compatibility of such methods is discussed.

Velocity and resistivity changes during freeze-thaw cycles in Berea sandstone

We report on simultaneous measurements of resistivity, compressional [Formula: see text], and shear [Formula: see text] velocities made during the temperature cycling of Berea sandstone while at elevated pressure. Temperatures were cycled through the freezing point of the saturating brine. The responses of resistivity and velocities are in phase but are asymmetrical as the brine freezes and thaws. Limited freezing causes no discernible damage to the core. Free water is present below the nominal freezing point of the brine. [Formula: see text], [Formula: see text], and resistivity change by 16%, 24%, and 500%, respectively, over the temperature range of [Formula: see text] at [Formula: see text] confining pressure.

Ground Resistance Measurement With Alternative Fall-of-Potential Method

An alternative fall-of-potential method is presented to measure on-line and in situ resistance of ground electrode systems in low-voltage distribution networks. It provides simultaneous resistance measurements of both equivalent ground electrode system of a substation and ground electrode of a premise. The method does not require usage of any auxiliary electrode, but employs two existing ground electrodes in the distribution network. The method has the advantage that it uses moderately high currents than the classical fall-of-potential method, and results are independent of test electrode positions. The method is especially useful in urbanized districts where it is difficult to apply the classical fall-of-potential method. Also, a capacitive potential probe was successfully tested in place of the current electrode used in the fall-of-potential method.

Biomechanical examination of a commonly used measure of spasticity

Background. An increase in the prevalence of neurological disability puts pressure on service providers to restrict costs associated with rehabilitation. Spasticity is an important neurological impairment for which many novel and expensive treatment options now exist. The antispastic effects of these techniques remain unexplored due to a paucity of valid outcome measures. Aim. To develop a biomechanical measure of resistance to passive movement, which could be used in routine clinical practice, and to examine the validity of the modified Ashworth scale. Study design. Repeated measure cross-section study on 16 subjects who had a unilateral stroke one-week previously and had no elbow contractures. Outcome measures. Simultaneous measurement of resistance to passive movement using a custom built measuring device and the modified Ashworth scale. Passive range of movement and velocity were also measured. The “catch”, a phenomenon associated with the modified Ashworth scale, was identified by the assessor using a horizontal visual analogue scale and biomechanically quantified using the residual calculated from a linear regression technique. Results. Half the study population had a modified Ashworth score greater than zero. The association between the two measures was poor ( κ=0.366). The speed and range of passive movement were greater in subjects with modified Ashworth score “0” ( P<0.05). Resistance to passive movement was higher in the impaired arm ( P<0.05) and tended to decrease with repeated measures and increasing speeds. Conclusions. A device to measure resistance to passive movement at the elbow was developed. The modified Ashworth scale may not provide a valid measure of spasticity but a measure of resistance to passive movement in an acute stroke population. Relevance Spasticity is an important neurological impairment for which many novel and expensive treatment options are being made available. There is a paucity of clinically usable outcomes to measure spasticity. A device to measure resistance to passive movement at the elbow, which was more reliable than the modified Ashworth scale was developed. This device may provide a much needed objective clinical measure to evaluate the efficacy of antispasticity treatment.

Chemical reactions in the detection of acetone and NO by a CeO 2 thin film

This work presents an attempt to apply the undoped n-type semiconductor CeO 2 in the detection of gases — acetone and NO — in an oxygen containing environment. However, in such gas mixture chemical reactions may take place at and near the hot sensor surface, changing the composition of the gas environment. The effect of CeO 2 — its catalytic activity — was studied in the oxidation of acetone and NO during their detection. For this purpose, a particular experimental set-up was planned and built: a special, flow type quartz microreactor connected to a mass spectrometer, offering the possibility for simultaneous resistance measurement and analysis of the near sensor gas composition. The sensor was operated both in self- and oven-heated mode between 20–900°C. The maximum sensitivity of CeO 2 was found between 350–450°C for both gases. While acetone causes a well measurable resistance change, the signal due to NO is quite small. The CeO 2 surface proved to be catalytically active in the oxidation of acetone resulting in the formation of CO 2. Surprisingly, the same surface led to the reduction of NO.

棒状磁性体試料の抵抗率と透磁率の同時測定

棒状磁性体試料の抵抗率と透磁率の同時測定

Stress Induced R&amp;rarr;B2 Transformation and Pseudoelasticity Associated with Twinning in a Ti&amp;ndash;Ni Alloy Including Aligned Particles of Ti&lt;SUB&gt;3&lt;/SUB&gt;Ni&lt;SUB&gt;4&lt;/SUB&gt;

A Ti-51 at%Ni alloy including aligned particles of Ti 3 Ni 4 precipitate formed by aging under an applied stress exhibits an anomalous transformation, i.e., stress induced R(martensite)→B2(parent) transformation. Confirmation of this transformation was made by tensile tests combined with simultaneous resistance measurements. This alloy also exhibits pseudoelasticity associated with twinning when tensile test is made at a temperature sufficiently below its transformation temperature, i.e., in the R-phase state. The stress induced R→B2 transformation and the pseudoelasticity in the R-phase state are due to the internal stress field formed by the aligned particles of Ti 3 Ni 4 .

Simultaneous resistivity onset and first-order vortex-lattice phase transition in Bi2Sr2CaCu2O8.

Simultaneous measurements of resistivity and local magnetization using microscopic Hall sensors were carried out on ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$Ca${\mathrm{Cu}}_{2}$${\mathrm{O}}_{8}$ crystals as a function of applied field and temperature. The resistivity onset is found to occur concurrently with the first-order vortex-lattice phase transition, determined by the equilibrium magnetization step. This behavior strongly suggests that the vortex lattice melts at the phase transition. The apparently reversible magnetization below the transition is ascribed to substantial flux creep.

Resistivity onset at the first-order vortex-lattice phase transition in Bi2Sr2CaCu2O8

Simultaneous measurements of resistivity and local magnetization using microscopic Hall sensors were carried out on Bi2Sr2CaCu2O8 (BSCCO) crystals as a function of applied field and temperature. The resistivity onset is found to occur concurrently with the first-order vortex-lattice phase transition, determined by the equilibrium magnetization step. This behavior is indicative of a vortex-lattice melting transition. The resistivity vanishes below the transition although the magnetization remains reversible.

Phase transformations in two-phase [formula omitted] alloys during continuous heating and cooling, studied by electrical resistivity measurements

The α → γ transformation in a Ti-47.5at.%Al alloy and the α → α 2 transformation in a Ti-40at.%Al alloy was studied by a novel computer-interfaced control-cum-data acquisition technique. In-situ, real-time, high-speed simultaneous measurements of resistivity and temperature were made in the system designed and constructed for this purpose. The experiments were made in the system designed and constructed for this purpose. The experiments were conducted in high vacuum. The samples were heated to the completely α region by controlled direct resistance heating, and cooled at various rates utilizing either controlled cooling algorithms or by varying the gas-jet quench. Temperature and resistivity changes were monitored during heating and cooling, and correlated with corresponding phase/microstructural changes. The results have shown that the γ phase is characterized by a low resistivity (about 50 μΩ cm at room temperature), whereas both α and α 2 phases have high resistivities (about 190 to 200 μΩ cm at room temperature). Because of the large difference in resistivities of the α and γ phases, large and measurable changes in resistivity can be observed when one of these phases transforms to the other. In the Ti-47.5Al alloy, the lamellar γ morphology was observed at slower cooling rates, the Widmanstatten-like at intermediate cooling rates, and a massive reaction at very high cooling rates. Preliminary results of the transformation start and completion temperatures for the various reactions as a function of cooling rates are presented.

Simultaneous measurement of resistivity and ac susceptibility on YBaCuO during thermal scanning

Abstract During thermal scanning, dc resistivity and ac susceptibility measurements have been performed on high-quality YBaCuO samples. Upon cooling, the appearance of the superconducting islands in the sample is accompanied by an initial increase of the resistivity. This unusual phenomenon, produced by local heat exchanges, may explain the differences between the superconducting onset temperatures determined by dc resistivity and by ac susceptibility measurements.

PSEUDOELASTIC BEHAVIOUR AND TWO WAY MEMORY EFFECT IN Cu-Zn-Al ALLOYS

Different types of training sequences and two memory effect (TWME) of polycristalline Cu-Zn-A1 alloys have been studied : Thin plates have been loaded in torsion and tests samples were loaded in pure tens ion. Simultaneous resistance measurements were made to know the volume fraction of the martensite. As Friend, it is shown that the first martensite platelets formed are the most operational for training. In addition, the relation between the pseudoelastic strain cPe and the martensite fraction z is non linear. The training can be quantified with the introduction of an internal kinematical stress $

A sensor for simultaneous measurement of resistivity and permeability using solenoid coils.

A method to simultaneously measure the resistivity and the permeability of a sample conductor from the difference in the complex impedance obtained by measuring the vectors of two identical circular solenoid coils, one surrounding and coaxial with the sample conductor moving at a constant speed and the other without the sample conductor is studied.The sample conductor in the study moved at a constant speed but when the measuring frequency is high enough, the effect of the speed on the complex impedance becomes insignificant.In this paper, the lowest possible measuring frequency which keeps, within 1%, the effect of the speed on the difference in the impedance between a static and a moving sample s shown. The resistivity and initial permeability of an iron sample were measured under such condition. These values were compared with values obtained by conventional methods. The difference in the values for the resistivity of an iron sample was within 8.3%, and for the initial permeability within 3%.

On the normal state resistivity and thermoelectric power of YBa2Cu3Ox: Experiments and interpretation

Abstract We report the results of simultaneous measurements of resistivity and of thermoelectric power of YBa 2 Cu 3 O x over a range of temperatures and oxygen pressures (100 K T p (O 2 )≤1 atm), both under conditions of equilibrium and of non-equilibrium with the ambient. The results have been interpreted using a simple model of conduction in a narrow band, where the carrier concentration in the band and the dominant scattering mechanism are determined by the concentration of oxygen vacancies. There is good agreement between the experimental results and the predictions of the model.

Simultaneous measurements of resistivity and thermopower of orthorhombic TaS3 under pressure.

The resistivity and thermoelectric power of orthorhombic ${\mathrm{TaS}}_{3}$ were measured simultaneously under pressure. The measurements reveal some features of the material which indicate a gap-state distribution similar to that in amorphous semiconductors. The discrepancies in energy gaps from different measurements and the large negative intercept of thermopower can be understood with this picture.

Thermoelectric Power Observation of Nearly-Commensurate Charge-Density Wave Phase in 1T-TaS2

The temperature dependence of Seebeck coefficient of 1T-TaS 2 is observed in the nearly-commensurate charge-density wave phase with simultaneous measurement of resistivity. Seebeck coefficient is mainly negative and shows complicated behaviors with large hysteresis. At about 280 K in the heating process, we found distinctive anomalies both in Seebeck coefficient and in resistivity, which may correspond to the new phase transition found in the thermal expansion measurement recently. The possible electronic structures in the nearly-commensurate phase are discussed on the basis of the Seebeck effect observations.

Simultaneous measurement of resistivity and magnetisation during precipitation in a gold-cobalt alloy

The precipitation kinetics of Au-2 at.% Co are investigated by simultaneous measurement of the saturation magnetisation and the electrical resistivity during isothermal annealing. The degree of precipitation determined using the two methods shows deviations of up to 15%; this discrepancy can be explained through the properties of the matrix and not the precipitates: Kondo scattering from cobalt atoms dissolved in gold as well as typical deviations from Matthiessen's rule must be considered for the interpretation of the results.

Simultaneous measurement of resistivity and temperature coefficient of resistivity of metallic thin films with the transient hot-strip method

The recently described transient hot-strip method for measuring thermal transport properties of solid insulators has been developed for simultaneously measuring the resistivity ϱ F and the temperature coefficient of resistivity (TCR) α F of metallic thin films. The experimental arrangement is similar to the well-known four-probe technique but the constant current pulse passed through the thin film is sufficiently high to increase its mean temperature by about 1 K. By measuring the time-varying increase or decrease in the resistance, information is obtained not only about the resistivity but also about the TCR. The main advantage of the method is the possibility to measure ϱ F and α F simultaneously without increasing or decreasing the temperature of the film by more than 1 K, i.e. without measurably changing the properties of the film. The method has been tested on unannealed copper films at room temperature.

Simultaneous measurement of resistivity and thermodynamic properties of liquid binary alloys. Application to Na-In, Na-Sn

A method is described for combining resistivity and thermodynamic observations of the same sample of a liquid binary alloy. The concentrations are varied in situ by using a solid electrolyte. The method is applied to Na-In and Na-Sn for which new resistivity and thermodynamic data are obtained up to 600 degrees C and for Na concentrations up to 0.7.