Diffusion and optical properties of Nd-doped sol-gel silica glasses

Abstract

Abstract Water and acetone neodymium nitrate solutions of up to 2.3 mol/l were used to impregnate porous sol-gel glass by immersing outgassed samples in the liquid for a specified time. Diffusion coefficients of the solvents were determined using the diaphragm technique. Concentrations of the solute in the pores of samples having various average pore diameters were determined from the intensity of 740 nm absorption band. The time dependence of the concentrations at various penetration depths was used to calculate the diffusion coefficients from Fick's law. Concentration gradients inside the materials were produced by controlling the time the sample was exposed to the solution. To maintain the concentration profile during the drying stage of the process, the mobility of the solvent must be faster than that of the solute. When the sample was sintered at 1000 K neodymium was incorporated into the glass network. It was shown that both diverging and converging gradient index lenses can be produced.