Synthesis of germanium oxide nanoparticles in low-pressure premixed flames.

Germanium oxide (GeOx) nanoparticles in the size range from 1 nm to 5 nm were synthesized in a low-pressure premixed H-2/O-2/Ar flat flame of 30 mbar. The premixed flame was doped with different amounts of tetramethyl germanium (Ge(CH3)(4)) ranging from 250 ppm to 2000 ppm. The influence of process parameters such as the amount of oxygen in the reaction gas, the condensation and reaction time, standoff, and precursor concentration with respect to growth of germanium oxide particles were investigated. The particles formed were analyzed in situ according to their mass and charge with a particle mass spectrometer. The specific surface area was determined ex situ by the BET method. The crystal form and chemical composition of produced nanopowders were characterized by EDX analysis and X-ray diffraction measurements.