Ag/Na Ion Exchange in Fluorophosphate Glasses and Formation of Ag Nanoparticles in the Bulk and on the Surface of the Glass

Nanoscale silver clusters and metal Ag nanoparticles embedded in fluorophosphate glass were produced by Na/Ag ion exchange and subsequent heat treatment. The studied ion exchange was found to provide the reduction of Ag+ ions to Ag0 and formation of the small Ag2–4 clusters featuring intensive luminescence. Treatment at the temperatures 320–410 °C resulted in the appearance of two surface plasmon resonance (SPR) bands corresponding to large clusters Agn (n = 11–70) with blue-shifted plasmonic band and metal Ag nanoparticles. Two different SERS substrates were obtained by an out-diffusion technique. A silver nanoisland structure was grown after heat treatment in the oxygen atmosphere. The nanoporous Ag films with a rough surface were grown in hydrogen atmosphere. The nanoporous Ag film was used as the substrate for SERS. It was found that sensitivity of the nanoporous Ag film grown on the fluorophosphate glass is close to results of SERS obtained on island structures grown on silicate glasses.