Magdalena Serrano De Caro

Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications.

Optical properties of Au-Ag alloys: An ellipsometric study

Optical properties of AgxAu1-x alloys were obtained experimentally using spectroscopic ellipsometry measurements on thin films fabricated by electron beam evaporation. Thin film thicknesses varied between 170 and 330 nm, making size effects negligible. Values of the complex refractive index of the pure metals were in good agreement with literature reports. The optical data set reported in this work can accurately reproduce experimental results. This is very important because there are not reliable and systematic optical constants for the alloys. Moreover, we show that the weighted average of the refractive indices of the pure metals fails to represent those of the alloys, not only in the region near the onset for interband transitions but also in the near-IR region.