Amorphous nanowires and crystalline thin films of SiO₂–Li₂O compounds obtained by combustion chemical vapour deposition

Amorphous silica films deposited by combustion chemical vapour deposition (CCVD) were modified by lithium addition in the precursor solution. The modified films were characterized by x-ray diffraction and scanning and transmission electron microscopy. The addition of lithium promoted the crystallization of Li2O–SiO2 compounds, mainly crystalline phases like Li2SiO3, Li2Si2O5, quartz and cristobalite. Besides this, the morphology of the film was modified, leading to the formation of acicular structures and nanowires. Selected area electron diffraction (SAED) and microprobe EDS analysis indicated that the nanowires are amorphous and probably constituted of silica.