Enhanced structure flexibility in oxygen-deficient open framework Al2W3O12: Evidence from heat capacity and high-pressure Raman spectroscopy

Abstract

This study explores the structural flexibility of oxygen-deficient Al₂W₃O₁₂, through heat capacity and high-pressure Raman spectroscopy measurements. The synthesis of oxygen-deficient Al₂W₃O₁₂ was achieved via controlled atmospheres, yielding samples with different oxygen vacancy concentrations. In oxygen-deficient samples, heat capacity data revealed enhanced low-temperature vibrational dynamics, and high-pressure Raman spectroscopy identified distinct shifts in vibrational modes, indicating increased structural flexibility compared to the defect-free phase. In addition, the critical pressures of phase transitions were lower in oxygen-deficient samples, corroborating their reduced stiffness and enhanced flexibility. These findings deepen our understanding of the role of oxygen vacancies in modulating the thermal and structural properties of open-framework materials, contributing to potential applications in thermal management and advanced ceramics.