The effect of sintering dopant incorporation in modified chemical vapor deposition

To determine the role of the diffusion of dopant (phosphorus, germanium, and fluorine) into silica particles and through the voids of porous soot during sintering, initially uniform soot layers are created with a stationary torch and then sintered at different rates, dopant partial pressures, and temperatures. The layer structure seen in modified chemical vapor deposition preforms is formed initially by gas phase thermal gradients during particle formation, but diffusion during sintering severely modifies the dopant level and slightly increases the concentration gradient within each layer