Synthesis of monodispersed GeO2 particles in nonionic reversed micelle systems - Control of particle size and crystal structure

On the basis of phase diagram of water solubilization or micelles in poly ( oxyethylene) (6) nonylphenyl ether (NP-6)/cyclohexane solutions, the synthe sis of GeO2 particles by the hydrolysis of germanium tetraethoxide (GTE) ha ve been carried out as a function of R-w (= [H2O]/[NP-6]), [NP-6] and [GTE] . No any particles were formed in monomer region. However, in both the reve rsed and swollen micelle regions relatively uniform spindle-like particles were produced, but they were turned to cubic-like polyhedral particles in W /O microemulsion region. These particle size depended markedly on R-w (= [H 2O]/[NP-6]), whereas they increased with increasing the concentration of NP -6 and inversely decreased with increasing GTE concentration. Particle size was decreased with increasing the apparent formation rate of particles and this formation rate depended on the states of solubilized water. On the ot her hand, X-ray and electron diffraction measurements indicated that any pa rticles were hexagonal and or-quartz typed GeO2, but spindle- and cubic-lik e particles were polycrystalline and single crystalline, respectively. X-Ra y diffraction measurement also indicated that such change of crystalline mo rphology was brought about by growth of (100) face of the side face of spin dle-like particles.