How Low Can You Go? New greener synthesis of barium sulfide

We’re pleased to announce our latest publication in RSC Advances, led by PhD student Will Tetlow in collaboration with Dr. Giulia Longo at Universitat Politècnica de València.

Barium sulfide (BaS) is a critical precursor for emerging technologies like the perovskite photovoltaic absorber BaZrS₃, but conventional production methods require extreme temperatures (>1000°C) and generate substantial CO₂ and SO₂ emissions—a significant environmental concern.

Will developed an innovative solid-state synthesis that dramatically reduces both temperature and environmental impact. By combining mechanochemical ball milling with a carefully controlled low-pressure thermal environment, we achieved 90% conversion to high-purity BaS at just 500°C—a remarkable 500°C reduction from literature methods.

The key breakthrough lies in leveraging Le Chatelier’s principle through precise gas flow control in custom-designed graphite vessels. This maintains optimal sulfur pressure while continuously removing water vapour, driving efficient BaS formation at unprecedented low temperatures. Real-time residual gas analysis confirmed that emissions are now 91% water vapour, compared to the CO₂/SO₂-dominated output of traditional routes. This work opens exciting possibilities for sustainable production of chalcogenide materials and accelerating next-generation photovoltaic technologies.

Read the Paper

Tetlow, W.D., Hutter, O.S., Etherington, M.K., Longo, G. RSC Advances, 15, 50446-50456, 2025 DOI: 10.1039/D5RA07445B