Hoa Nguyen / Chemistry & Biochemistry / Faculty Mentor: Robin Macaluso
Heteroanionic approach in material design offers an exciting opportunity to strategically target new materials and adjust their physical properties. Our study aims to investigate the local structure of oxychalcogenide pyrochlore Sn2Nb2O7-xSx to understand how changes in crystalline and electronic structure correlate with the narrowing of its band gap with increasing sulfur content. X-ray total scattering and pair distribution function (PDF) studies were used to characterize structural distortions impacted by Sn2+ 5s2 stereochemically active lone pairs, anions covalency and defects. Sn2Nb2O7-xSx adopt the average cubic structure (Fd3 ̅m), with Sn2+ and O2- strongly displaced from their ideal crystallographic sites. PDF analysis indicates the distortion of the Sn and O pair at local distances. We will discuss the relationship between sulfur concentration and local structural distortions on the band gap, which contributes to the vibrant yellow to orange-red color of these pigments.
Leave a Reply