High Purity Cadmium Research Articles

Recovery of Defects Following Deformation of High Purity Cadmium at 78°K

AbstractThe recovery spectra in 99.99% and 99.9999% polycrystalline cadmium wire plastically deformed at 78 °K has been studied using electrical resistivity as an index of defect concentration. The anneals were carried out in 10 °K steps up to room temperatures using a series of sequential isotherms on a single specimen for a duration of four minutes at each temperature and by annealing individual specimens at only one temperature for 16 minutes. Some annealing takes place at each step but two prominent recovery peaks were observed at the same temperature for both specimens. The recovery peaks in the less pure specimen appear to have a broader energy distribution. The energy of the most prominent peak in the 99.9999% cadmium is 0.24 eV and the energy for the corresponding peak in the 99.99% cadmium is 0.34 eV. This peak is attributed to vacancy motion and an explanation for the energy difference in terms of impurity‐vacancy binding is suggested. On this basis, an impurity‐vacancy binding energy of 0.10 eV and a vacancy motion energy of 0.24 eV are deduced.

INTERCOMPARISON OF 11 RESISTANCE THERMOMETERS AT THE ICE, STEAM, TIN, CADMIUM, AND ZINC POINTS

Eleven standard platinum resistance thermometers, including thermometers having three different types of construction, have been intercompared at the triple point of water, boiling point of water, and the liquidus points of high purity tin, cadmium, and zinc. Temperature coefficients determined from measurements at the triple and boiling points of water and the zinc point were used to calibrate the thermometers for the temperature calculations on measurements at the tin and cadmium points. The results show that, although the measurements were made at a precision of about 0.0002 °C at each fixed point, distinctive deviations from quadratic resistance–temperature relations were not found for the 11 thermometers. This verification of the quadratic form for the resistance–temperature relationship realized with these thermometers gives strong support for the use of the liquidus point of high purity indium, tin, or cadmium as a precision alternative to the steam point on the International Temperature Scale.

High‐Pressure, High‐Temperature Growth of Cadmium Sulfide Crystals

A process is described for growing cadmium sulfide crystals of uniform size, shape, and homogeneity from the melt. Structure and electrical characteristics of the crystals are discussed, and segregation data on several impurity species are given. A method is described for preparing high purity cadmium sulfide powder by the purification of cadmium and sulfur followed by direct combination of the elements.

The polarographic determination of thallium, iron and copper in high-purity cadmium metal

ABS>A polarographic technique is described by which extraction of the trichlorides, in essentially the same centrations under consideration and is separately determined by an extraction procedure with sodium diethyldithiocarbamate. An alternative polarographic procedure is described for the determination of copper, in which an ammonium chloride-ammonium hydroxide base electrolyte is used. (auth)

THE FREEZING POINTS OF HIGH PURITY METALS AS PRECISION TEMPERATURE STANDARDS: II. AN INVESTIGATION OF THE FREEZING TEMPERATURES OF ZINC, CADMIUM, AND TIN

An investigation of freezing and melting temperatures with platinum resistance thermometry on high purity zinc, cadmium, and tin has been carried out. Using appropriate techniques, plateaus of essentially constant (< ±0.0001 °C.) temperature with durations of over 1 hour are readily obtained on the cooling curves of these metals. For series of freezes on particular samples, the standard deviations of the respective plateau temperatures were found to be of the order of ±0.0002 °C. It was not possible to distinguish among the plateau temperatures of three samples selected from different distillation batches of New Jersey S.P. zinc. Evidence is presented on the long term stability ([Formula: see text] years) of the plateau freezing temperature of S.P. zinc determined with six standard thermometers. The pressure effects on the freezing temperatures were found to be 0.0043 °C, 0.0062 °C, and 0.0033 °C. per atmosphere for zinc, cadmium, and tin respectively.Thermal analysis of these high purity metals reveals alloy structures and other features associated with nucleation, coring, and annealing phenomena; typical thermal curves are shown.