Original Article

Y–O–S and Ce–O–S equilibria in liquid copper

¹ School of Materials Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, PR China
² International Institute for Innovation, Jiangxi University of Science and Technology, Nanchang 330013, PR China
³ Xinyu University, Xinyu 338000, PR China

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 26 August 2025
Accepted: 1 December 2025

Abstract

This study proposes a hybrid experimental-thermodynamic approach to determine the solubility products of rare earth oxysulfides and establish phase equilibria in molten copper. By combining limited experimental data at 1473 K with thermodynamic modeling, we derived temperature-dependent solubility product expressions (1340–1500 K) for Y₂O₃, YS, Y₂O₂S, Ce₂O₃, CeS, and Ce₂O₂S. Thermodynamic analysis conclusively rules out the formation of Y₂S₃ and Ce₂S₃. We systematically analyzed the formation criteria for RE₂O₂S, RES, and RE₂O₃ phases in liquid copper and constructed Y/Ce–O–S equilibrium diagrams at 1373 K and 1473 K. These results can provide essential foundational data for copper metallurgy for rare earth additions.