Explain the complete phase assemblage in metal–PBM grinding reactions

Establish a complete explanation for all phases observed after grinding Pb, Sn, Cu, and Au powders with methylammonium polybromide melts, including the respective roles of incomplete reaction, bromine loss, oxygen exposure, and uncontrolled humidity.

Background

Grinding experiments produced unreacted methylammonium bromide, residual metals, metal halides, and competing perovskite-related phases. The authors attribute these observations provisionally to factors such as bromine volatilization, open-air processing, and uncontrolled humidity, but do not establish which mechanisms account for the full set of products. Resolving this issue is important for interpreting the reaction chemistry and for determining whether grinding can be adapted into a reliable production route.

References

While we do not have a complete explanation for all observed phases, one possible source of these findings is that the grinding was not done in an air-tight environment, nor under controlled humidity conditions.

— A Universal Polybromide Melt Strategy for the Direct Conversion of Metals into Optoelectronic-Grade Bromide Perovskites  (2610.12278 - Mondal et al., 8 Oct 2026) in Section 3.2.3, p. 13