The production of porous glass microspheres by the nuclear track technique

Abstract

Abstract The nuclear track technique (NTT) is used to produce porous glass microspheres. The nuclear tracks randomly penetrate the material so that the resultant pores are interconnected. The result of this process is the creation of latent, radiation-damaged regions by the charged particles emitted from the neutron-induced fissioning of 235 U, an isotope of uranium which in trace quantities either naturally occurs in or surrounds the microspheres. The damaged regions, or “tracks” are then enlarged to optically visible tracks with the aid of a light microscope by chemically etching the material. The number of tracks or pores created both at the surface and within the microsphere is dependent upon the neutron fluence used to induce the fission of 235 U, provided that the bulk uranium is constant in the microspheres. Pore diameter is determined by the concentration of the etching solution and the etching time.