Spectroscopic analysis of Eu3+ doped silica-titania-polydimethylsiloxane hybrid ORMOSILs.

Eu3+ doped silica-titania-polydimethylsiloxane hybrid ORMOSILs were synthesized via a non-hydrolytic sol-gel route. The structural and thermal analyses of the samples confirmed that the matrix structure remains unaffected by doping with different concentrations of Eu3+ ions. Photoluminescence (PL) studies performed at 394 nm on Eu3+ doped ORMOSILs imply that they emit broad blue host emission and the characteristic Eu3+ red emissions simultaneously. Also, the samples were excited at the charge transfer (CT) band and this confirmed the existence of an energy transfer path from the host to the Eu3+ ions via Ti4+-O2--Eu3+ bonds. The phonon energy of the host matrix was estimated by phonon sideband (PSB) analysis and the results were substantiated by Raman analysis. Judd-Ofelt (JO) parameters were also evaluated which give details about the local surroundings of the Eu3+ ions in the system and these parameters were further used for predicting the radiative properties of 5D0 → 7F1,2,4 transitions of Eu3+ ions. Furthermore, the quantum efficiency and CIE co-ordinates were evaluated and it was found that Eu3+ doped silica-titania-polydimethylsiloxane ORMOSIL has an intense pinkish red emission with a quantum efficiency of 30.7%.

A novel blue luminescent material Na2[Co(C2O4)2(H2O)2]·6H2O: synthesis, structure, luminescence and magnetic properties.

The synthesis, crystal structure and physical properties of new disodium trans-diaquabis(oxalato)cobaltate(ii)hexahydrate {Na2[Co(C2O4)2(H2O)2]·6H2O} crystals have been investigated. Single crystal X-ray analysis reveals that this compound crystallizes in the triclinic system with the space group P1[combining macron]. The structure of this complex consists of [Co(C2O4)2(H2O)2](2-) anionic units with a slightly distorted octahedral geometry of cobalt surrounded by four oxygen atoms of two oxalate groups. The anionic units are interlinked by two Na(+) ions with different octahedral and distorted octahedral environments. The electronic absorption spectra of the compound exhibit bands at 208, 246 and 526 nm in the UV and visible regions. A strong blue luminescence was observed at room temperature when excited at 355 nm. The M(H) curve at 2 K shows a significant nonlinear behaviour with almost zero coercivity which clearly indicates an extremely weak antiferromagnetic/ferromagnetic state of the complex.