Thermodynamic Stability of Tungsten Dichalcogenides

Tungsten dichalcogenides, i.e., WX₂ (X = S, Se, and Te), represent a critical class of materials with promising applications in nanoelectronics, photovoltaics, thermoelectrics, and quantum technologies. However, the performance of these dichalcogenides is often limited due to vaporization loss of chalcogens at elevated temperatures, emphasizing the necessity to understand their thermodynamic stability in operational conditions. In this study, we investigate the vaporization behavior and thermodynamic stability of WX₂ compounds using a high-temperature Knudsen effusion mass spectrometer (HT-KEMS). The vapor pressures of S, Se, and Te-bearing species over WS₂, WSe₂, and WTe₂ were derived from their respective ion intensities. By analyzing the temperature-dependent vapor pressures, the Gibbs energies of formation for WS₂, WSe₂, and WTe₂ have been derived. Our findings provide essential insights into the thermal stability of tungsten dichalcogenides, facilitating their optimized use in high-temperature applications.