ions in low phonon antimony based dichroic metallo-dielectric nanocomposites

Eu ions and elliptical Au nanoparticles incorporated new antimony based reducing dielectric (here glass) matrix, K2O-B2O3-Sb2O3 (KBS), has been prepared by a new single-step methodology involving selective thermochemical reduction without employing any external reducing agent. X-ray diffraction (XRD) and selected area electron diffraction (SAED) results of these hybrid nanocomposites indicate that Au nanoparticles are grown along the (111) and (200) plane direction. The transmission electron microscopic (TEM) image reveals formation of elliptical Au nanoparticles of major axis (diagonal) 5 to 12 nm range. Dichroic behavior is due to elliptical shape of Au nanoparticles having aspect ratio of about 1.2. Presence of Au nanoparticles introduces a local crystalline environment and perturbs the local site symmetry around the Eu ions resulting in well-resolved stark splitting of the electric dipole D0– F2 emission transition into two components (617 and 640 nm). The photoluminescence intensity of the 640 nm red emission of Eu drastically enhances by ~ 8 folds in presence of Au nanoparticles and then attenuates with further increase in Au concentration. This advocates two types of nano Au distribution, clustered and dispersed sites, around the Eu ions. On the contrary, the magnetic dipole D0– F1 orange (596 nm) transition remain almost unaffected by the presence of nano Au. Local field enhancement induced by plasmonic Au is found to be