Synthesis of silica microcoils by catalyst-free carbothermic method

Amorphous silica microcoils were prepared by catalyst-free carbothermal route. The lengths of them could reach as long as several hundreds of micrometers. From the morphological perspective, the microcoils could be grouped into two categories: one type was formed from an individual microwire, whereas the other type consisted of two intertwined microwires. The silica microcoils were formed spontaneously in a conventional vapor–solid growth process and the competition between the fluctuation of the pressure and the growth inertia was invoked to explain the formation of the coiled morphology. The photoluminescence (PL) spectrum of the product showed two bands centered at 416 nm and 438 nm under excitation at 320 nm.