ITO resistivity is change almost three times at 550C, Will be  better if you will use FTO.

As previously stated ITO loses conductivity after 400 deg cel. You can try FTO which i've used upto 600 deg cel and quite stable.  AZO is another alternative. Price is quite cheaper for AZO and FTO compared to ITO. 

you should use FTO in this case. I can help if you want

Thanks vipin. Do we need to protect FTO from h2s environment at 550c or not. If yes how?

Dear Dr. Gupta,

Maybe you can use a thin SnO2 protection layer on top of the ITO. Some 20 nm should be adequate.

Hi,

I experienced that FTO turns yellow (when used Ar+S) or black (when used H2S) in my annealing tube (470-550C) converting to sulfide (may be) and looses it's conductivity. Similar case for Mo. What would be a smart way to deal with it, scratching off??? I tried to do that, for FTO-colored material goes off, leaving no conductivity.

FYI: I also put SnS powder in the tube.

Try to cover partially with AL foil/sheet and press it to stay flat or clamp it with metal clips.

If gap is visible between Al sheet and FTO, then FTO will be affected ! Have you considered other TCOs such as AZO ?

All the best !