Figure 6. Elemental analysis.

EDS linescans of (a) tungsten (W-L lines) and (b) oxygen (O-K lines) along cross-sections, running from substrate to top layer, of the refractory tungsten–hafnium dioxide metamaterial before annealing (brown), after heat cycling to 1,000 °C (blue), and after heat cycling to 1,100 °C (green). The curves are artificially offset along the y axis for clarity. The oxygen figure shows a clear interlayer diffusion as the dips corresponding to tungsten layers are much weaker for the green data set. In contrast, the tungsten figure shows no significant alterations, signalling that the overall multilayer structure is stable beyond 1,100 °C.