Low-Temperature, Low-Environmental-Impact Synthesis of Barium Sulphide for Perovskite Applications

Barium sulphide (BaS) serves as a crucial precursor for advanced barium-based materials, including the emerging perovskite absorber BaZrS₃.[1] However, conventional BaS production methods are highly energy-intensive, requiring temperatures exceeding 1000 °C [2,3] and emitting large quantities of CO₂ and SO₂,[3,4] raising environmental concerns.

This work presents a novel solid-state synthesis route for BaS that drastically reduces the environmental and energy demands. By employing a finely milled mixture of barium hydroxide [Ba(OH)₂] and elemental sulphur, we achieve an efficient conversion (85%) to BaS at a remarkably low annealing temperature of 500°C.

The process is enabled by a unique low-pressure annealing environment, which facilitates the rapid vaporization of H₂O byproducts while maintaining a controlled sulphur partial pressure. This balance prevents unwanted side reactions and enhances the conversion efficiency. Furthermore, this method is highly scalable and compatible with industrial processes, offering a sustainable and economically viable pathway for BaS production.