Simultaneous Resistance Measurements Research Articles

Lattice contraction in electron irradiated 1T-TaS 2

A strong volume contraction of 0.2 ± 0.1 unit cell volumes per displaced atom has been observed in electron irradiated 1T-TaS 2. It happens along the c-axis and is explained as a consequence of an increase in the interlayer coupling caused by the metallic interstitials in the Van der Waals gap. Simultaneous resistivity measurements revealed the suppression of the ordered charge density wave phases. The volume effect causing this suppression is one order of magnitude smaller than under external pressure 13,14. This suggests that the defects perturb the charge density waves mostly locally.

The potential and resistance profile of Necturus gallbladder cells.

Necturus gallbladders were mounted in a modified Ussing chamber and the open circuit potential as well as the IR drop in response to transepithelial current were recorded while passing 2.7 molar KCl-filled microelectrodes in steps of 2–7 μm from the mucosal compartment across the cell into the subepithelial space and back. Using high-resistance electrodes the intracellular electrical potential was found to be independent of the depth of penetration of the electrode into the cell. It averaged −57.9 ±4.5 mV (n=39) with reference to the mucosal solution. Similarly, the resistance between microelectrode tip and mucosal solution was independent of the depth of insertion, indicating that the major part of the IR drop in response to transepithelial currents of 100 μA/cm2 density occured at the cell membranes and that the IR drop inside the cytoplasm was negligibly small. The latter result agrees with quantitative estimates based on the cytoplasmic resistivity of other cells. Using low-resistance microelectrodes the existence of intracellular potential gradients could be simulated. The simultaneous resistance measurements, however, revealed that initial low potential readings must be interpreted as incomplete or leaky impalements. We conclude that active solute and water transport across Necturus gallbladder epithelium does not generate significant intracellular potential gradients.

Use of thin films for studying order-disorder transformations

Thin films are used to investigate the transformation by heat treatment of a disordered phase into an ordered phase in two different cases: compositional disorder in the case of metallic (Au-Cu) alloys, and positional disorder in the case of an amorphous semiconductor (Ge). The transformation is followed by simultaneous resistance measurements and controlled by electron diffraction and electron microscopy; its effects on the optical properties are measured. The use of thin films allows one to characterize accurately the phases before and after the transformation, and to check that the transformation has been completed.

Simultaneous measurements of resistivity and thermoelectric power during ordering of Au 3 Cu

Simultaneous measurements of resistivity and thermoelectric power during ordering of Au 3 Cu

Microwave measurement of resistivity

A mathematical description is given of the possible use of pulse modulation of millimetre e.m. waves for extending the range and flexibility of a previously described method for the simultaneous measurement of resistivity and thickness of germanium epitaxial layers.

The Debye temperature of AuCu 3 as a function of long-range order parameter

Simultaneous measurements of resistance have been made on partially ordered and disordered AuCu 3 wires. The resistance measurements are made over the temperature range from 4.2°K to 77°K. The differing behavior of the temperature dependent portions of the resistivities of the two wires has been interpreted as an increase of Debye temperature in the ordered sample. The total change observed from disorder to complete order is 22 degrees. Some thermodynamic implications of these changes are discussed. A suggestion is made that the appearance of long-range order, as distinguished from short-range order, must be accompanied by changes in the spectrum of lattice oscillation. The basis for this suggestion is presented.

The influence of cold work and radiation damage on the debye temperature of copper

Copper wires have been cold-worked or subjected to radiation damage. Simultaneous measurements of resistance have been made on a damaged wire and a well-annealed wire. The resistance measurements are made over the temperature range from 4.2°K to 77°K. The differing behavior of the temperature-dependent portions of the resistivities of the two wires has been interpreted as a decrease of Debye temperature in the damaged sample. The maximum change observed is 45°. The thermal annealing of this change has been followed. Some thermodynamic implications of these changes are suggested.