TEM studies on the changes of the composition in LGS and CTGS substrates covered with a RuAl metallization and on the phase formation within the RuAl film after heat treatment at 600 and 800 °C

•Investigation of the thermal stability of RuAl thin films on LGS and CTGS.•The RuAl phase is stable on LGS and CTGS up to 600 °C in vacuum.•Annealing at 800 °C leads to complete oxidation of the Al on LGS and partly on CTGS.•TEM analysis shows local inhomogeneities within the 800 °C heated LGS substrate.•The upper 50–100 nm of the 800 °C heated CTGS substrate is completely inhomogeneous.

A detailed transmission electron microscopy analysis of LGS and CTGS substrates which are covered with RuAl thin films is performed after annealing the system at 600 and 800 °C for 10 h under high vacuum conditions. Energy dispersive X-ray spectroscopy is applied to reveal the changes of the chemical composition of the substrates as well as of the metallization. While after annealing at 600 °C hardly any changes occur in the films and in the substrate, huge inhomogeneities are found within the substrates after annealing at 800 °C and a strong oxidation occurs within the RuAl films.

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