Large-scale synthesis of closed loop silica fibers

A noncatalytic vapor transport process has been employed to prepare large scales of closed loop SiO₂ fibers. To the best of our knowledge, such unique morphologies made from the noncatalytic vapor transport process have not yet been reported. Among the products, some interesting morphologies are observed. One phenomenon is connective closed loops growth, and the other is the discontinuity of the loop growth within one silica fiber. Studies find the as-synthesized silica fibers are amorphous in nature. Analysis of a number of fibers shows that the diameters of these SiO₂ fibers vary from 700 nm to 1 μm, and the diameter of the branches is similar to that of the parent one. The photoluminescence spectrum of the silica fibers shows two strong blue emission peaks at 409 nm (3.03 eV) and 448 nm (2.76 eV) under excitation at 260 nm. The resultant loop SiO₂ fibers should not only facilitate their structure-property characterization but also allow them to be effectively incorporated into devices for practical applications.