Microstructural and spectroscopic study of sol–gel derived Nd-doped silica glasses

Nd-doped silica glasses have been prepared from a base catalyzed sol–gel solution. The photoluminescence (PL) spectrum and lifetime of the glasses have been studied with respect to their microstructure and chemical composition. It is shown that the glass microstructure depends closely on the solution pH and Nd-doping. A slow decay component (SDC) of the 1060 nm PL, with a lifetime of around 300 μs, and a fast decay component (FDC), with a lifetime of around 0.3 μs, have been identified. The FDC is attributed to Nd3+ ions clusterization inside the silica matrix. It has been shown that the FDC can be almost extinguished and the SDC component substantially increased by Al co-doping. The reasons are twofold: (i) inhibition of the Nd3+ ions clusterization and (ii) intrinsically better PL efficiency of Al co-doped glasses at 1060 nm. Depending on the solution pH, the amount of Nd in the glass can be noticeably increased while preventing a detrimental rare earth clusterization. Thus, a greater glass PL efficiency can be expected.