Sides William D, Hassani Ehsan, Pappas David P, Hu Yang, Oh Tae-Sik, Huang Qiang
Department of Chemical and Biological Engineering, University of Alabama, Tuscaloosa, Alabama 35487, USA.
Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849, USA.
J Appl Phys. 2020 Feb;127(8). doi: 10.1063/1.5139909.
The relationship between superconductivity and the film preparation conditions, i.e., the thickness and annealing process, in electrodeposited rhenium (Re) films is studied in order to understand the effect of grain size and impurities on the film's superconducting transition temperature, . A water-in-salt electrolyte was used to mitigate embrittlement by reducing hydrogen evolution at the cathode where Re is deposited. The as-deposited films exhibit a highly disordered atomic structure and superconductivity up to a temperature of > 5.8 K, consistent with that expected from amorphous films. A reduction of the critical temperature of superconductivity is found to accompany grain growth. However, for film thicknesses less than 300 nm the grain growth is inhibited. This leads to a retention of the critical temperature upon annealing these thin films. A reduction of impurities in Re films is found to accompany annealing, and significant grain growth is found to proceed rapidly at temperatures of 220 °C in inert atmospheres. The introduction of hydrogen in the annealing ambient further facilitates this grain growth.
研究了电沉积铼（Re）薄膜中超导性与薄膜制备条件（即厚度和退火工艺）之间的关系，以了解晶粒尺寸和杂质对薄膜超导转变温度的影响。采用盐水电解质来减少在沉积Re的阴极处析氢，从而减轻脆化。沉积态薄膜呈现出高度无序的原子结构，在温度高于5.8 K时具有超导性，这与非晶薄膜的预期相符。发现超导临界温度的降低伴随着晶粒生长。然而，对于厚度小于300 nm的薄膜，晶粒生长受到抑制。这导致在对这些薄膜进行退火时临界温度得以保留。发现Re薄膜中的杂质在退火时会减少，并且在惰性气氛中于220 °C的温度下会迅速发生显著的晶粒生长。在退火环境中引入氢气进一步促进了这种晶粒生长。
