Plasmonic Au_xAg_y bimetallic alloy nanoparticles enhanced photoluminescence upconversion of Er³⁺ ions in antimony glass hybrid nanocomposites

Abstract

Er³⁺ ions and spherical (3–23 nm) Au _x Ag _y bimetallic alloy (where x = 18–96 and y = 4–82, atom %) nanoparticles incorporated novel antimony oxide based reducing dielectric (glass) matrix, K₂O–B₂O₃–Sb₂O₃ (KBS), has been synthesized by a new single step methodology involving selective thermochemical reduction. Their absorption spectra show a single tunable (536–679 nm) surface plasmon resonance band along with the typical absorption peaks of the Er³⁺ ion. X-ray and SAED indicate the formation of (111) and (200) planes of Au _x Ag _y alloy. The luminescence intensity of two prominent emission bands of Er³⁺ ions centered at 536 (green) and 645 (red) nm due to ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions were observed to be strongly dependent on the Au _x Ag _y nanoparticle composition. Both the bands undergo a maximum of 1.5- and 4.5-fold intensity enhancement respectively in the presence of the Ag₅₆Au₄₄ alloy (atom %) due to plasmon induced local field enhancement.

Keywords:

• gold–silver alloy nanoparticles
• erbium (III)
• nanocomposite
• upconversion
• enhanced fluorescence
• antimony oxide glass

Acknowledgements

TS gratefully acknowledges the financial support of the Council of Scientific and Industrial Research (CSIR), New Delhi in the form of NET-SRF under sanction number 31/015(0060)/2007-EMR-1. The authors gratefully thank the Director of the institute for his kind permission to publish this work. The technical supports provided by the infrastructural facility (X-ray Division) of this institute and National TEM facility center, IIT Kharagpur, are also thankfully acknowledged.