GPT-4 does it very well though. (Not saying OP used it, was just curious if that'd work.)
Prompt:
> Observation of zero resistance above 100∘ K in Pb10−xCux(PO4)6O
> convert this to a title, with the correct usage of unicode
Output:
> Observation of Zero Resistance Above 100 K in Pb₁₀₋ₓCuₓ(PO₄)₆O