Fabrication of Glass Micro- and Nanospheres from Liquid Precursors Using Droplet Generation and Sol-Gel Processing

Abstract

AbstractTwo novel methods particularly suitable for continuously fabricating uniform glass spheres are described, one suitable for spheres micrometers to millimeters in diameter and the other for spheres of diameters in the submicron range, down to tens of nanometers. Both methods start from liquid precursors and combine droplet generation which is effected by a nozzle with sol-gel processing. One difference is that in the latter method, which is termed the charged liquid cluster beam (CLCB) technique, one employs flow-limited field-injection electrostatic spraying to further reduce the size of the drops to the nanometer range in the droplet generation process. Using the two methods, uniform hollow silica aerogel spheres, micrometer to millimeter in diameter, of controlled porosity and silica spheres with diameters in the nanometer range were produced. By utilizing the appropriate liquid precursors, the present methods can fabricate spheres composed of a variety of materials, including glass. Due to its ability to fabricate nanodrops, the CLCB technique is suited to fabricating nanoparticles as well as thin films of controlled stoichiometry and chemical composition.