  Materials such as W, TiN, and SrRuO3 (SRO) have been suggested as promising
alternatives to Au and Ag in plasmonic applications owing to their refractory
properties. However, investigation of the reproducibility of the optical
properties after thermal cycling at high operational temperatures is so far
lacking. Here, thin films of W, Mo, Ti, TiN, TiON, Ag, Au, and SrRuO3 are
investigated to assess their viability for robust refractory plasmonic
applications. Films ranging in thickness from 50 - 180 nm are deposited on MgO
and Si substrates by RF magnetron sputtering and, in the case of SrRuO3, pulsed
laser deposition, prior to characterisation by means of AFM, XRD, spectroscopic
ellipsometry, and DC resistivity. Measurements are conducted before and after
annealing in air at temperatures ranging from 300 - 1000{\deg} C for one hour,
to establish the maximum cycling temperature and potential longevity at
temperature for each material. It is found that SrRuO3 retains metallic
behaviour after annealing at 800{\deg} C, however, importantly, the optical
properties of TiN and TiON are degraded as a result of oxidation. Nevertheless,
both TiN and TiON may be better suited than Au or SRO for high temperature
applications operating under vacuum conditions.
