Superconducting Properties of Technetium

Abstract

Isothermal magnetization measurements are reported for technetium in the superconducting state from 1.5°K to the transition temperature after various stages of heat treatment up to 2000°C. The purer sample studied (r = 120, where r is the ratio of resistance at 295°K to the resistance at 9°K) was found to have a transition temperature of 7.73±0.02°K, and was destroyed in an early attempt at annealing, while the second sample (r = 97), which had a transition temperature of 7.77±0.02°K, was studied more thoroughly. The magnetic behavior of this material is characteristic of a type-II superconductor, and the experimental temperature dependence of H C 2, the upper critical field, is compared with existing theories. Upper limits to the thermodynamic critical field H c (t), which have been obtained by integrating under the nonreversible magnetization curves observed after the 2000°C heat treatment, lead to an extrapolated value of H c (0) = 1410 Oe, and a Ginzburg-Landau parameter of KI(1) =0.92. The data suggest that technetium is a weakcoupling superconductor of the BCS type, and the results are examined for self-consistency.

Thermodynamics of technetium: reconciling theory and experiment using density functional perturbation analysis

“…The basic properties of the radioelement technetium, discovered by Perrier and Segre in 1937, 1 were known by the mid-1970s, from the early studies of its crystallographic structure, [2][3][4][5][6][7][8][9] mechanical properties, 10 superconducting properties, 11,12 electrical resistivity, 13,14 magnetic susceptibility, 14 thermal diffusivity 5,14 and heat capacity. 14,15 Owing to its high critical superconducting transition temperature of T c = 7.85 K at zero pressureonly second among the elements to that of niobium (T c = 9.26 K) -, the low-temperature properties of technetium metal have been extensively investigated.…”

Fabrication and Chemical Durability of Ceramic Technetium-Based Pyrochlores and Perovskites as Potential Waste Forms

“…The critical temperatures of the strontium technetates SrTcO 3 and Sr 2 TcO 4 , T c = 7.8 K and 7 K, respectively, (Fig. 4) are in the vicinity of the Tc for Tc-metal with 7.73(2) K [10]. However, in regard to the low sintering temperatures (770 °C, 550 °C), the formation of metallic Tc impurities caused by disproportionation of TcO 2 is unlikely.…”

Robust T c in element molybdenum up to 160 GPa

“…As the most straightforward material systems, elemental materials provide the best platforms for studying superconductivity. The superconductivity of 29 elements [1,2] was observed at ambient pressure, such as beryllium (Be), [3] technetium (Tc), [4] and hafnium (Hf), [5] with the transition metal niobium exhibiting the highest superconducting critical temperature of 9.2 K. [6,7] As a powerful means of altering material properties, high pressure can change the microscopic structure of materials and significantly increase the T c of certain elements. [8][9][10] With the introduction of pressure, the superconducting transition temperatures of some elements are significantly increased, such as lithium (Li), [11] zirconium (Zr), [12] and lanthanum (La).…”