(637g) Strained Low Dimensional Sr1-XTiyNb1-YO3+? nanoparticles for Infrared Light Harvesting

The family of Sr_1-xNb_1-yO_3+δ (SNO) metal oxides has attracted interest for their plasmonic and low-loss response making them promising materials for photovoltaic and photocatalytic devices. SNO metal oxides have been synthesized using modern thin-film technology but strain engineering is limited to film/substrate lattice mismatch and deposition pressure. To address this problem, SNO nanocrystals synthesized by wet chemistry techniques allowing for direct control of the compositional, morphological, and external stresses are of interest. The current project proposes leveraging nanoparticle stoichiometry to investigate the plasmon resonance in a host nanocrystal (SrTiO₃) that has been doped with Nb ions, Sr_1-xTi_yNb_1-yO_3+δ (STNO).

In this work, STNO nanoparticles (<100 nm) were synthesized via a two-step co-precipitation/molten salt technique. Preliminary physical characterization identifies the crystal structure of the STNO nanoparticles as cubic SrTiO₃ phase. The resultant strain (~1%) on the dopant in the host matrix was calculated based on the cell expansion observed from X-ray diffraction. X-ray photoelectron spectroscopy shows that the resultant strain is due to the of presence of Nb in mixed +4, +5, and +3 oxidation states. X-ray absorption spectroscopy was performed to confirm the presence of octahedrally coordinated Nb⁴⁺. Additionally, the octahedral coordination of Nb⁴⁺ is correlated to enhancement in the optical absorption using UV-Vis spectroscopy. These results on low dimensional Nb-doped SrTiO₃ nanoparticles demonstrate a capacity for infrared light harvesting which has potential for applications in optical communication, remote sensing, spectroscopy, and thermal imaging.