Behavior of Microstrain in Nd 3+ -Sensitized Near-Infrared Upconverting Core-Shell Nanocrystals for Defect-Induced Tailoring of Luminescence Intensity

• Published in: Nano letters Vol. 24; no. 21; pp. 6320 - 6329
• Main Authors: Pandey, Panchanan, Tripathi, Shilpa, Singh, Manvendra Narayan, Sharma, Rajendra Kumar, Giri, Supratim
• Format: Journal Article
• Language: English
• Published: United States 29.05.2024
• Subjects: core−shell nanocrystal; lattice mismatch; local disorder; upconversion luminescence; microstrain
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.4c01077

In an attempt to optimize the upconversion luminescence (UCL) output of a Nd -sensitized near-infrared (808 nm) upconverting core-shell (CS) nanocrystal through deliberate incorporation of lattice defects, a comprehensive analysis of microstrain both at the CS interface and within the core layer was performed using integral breadth calculation of high-energy synchrotron X-ray (λ = 0.568551 Å) diffraction. An atomic level interpretation of such microstrain was performed using pair distribution function analysis of the high-energy total scattering. The core NC developed compressive microstrain, which gradually transformed into tensile microstrain with the growth of the epitaxial shell. Such a reversal was rationalized in terms of a consistent negative lattice mismatch. Upon introduction of lattice defects into the CS systems upon incorporation of Li , the corresponding UCL intensity was maximized at some specific Li incorporation, where the tensile microstrain of CS, compressive microstrain of the core, and atomic level disorders exhibited their respective extreme values irrespective of the activator ions.