Nb 2 O 5 coating of glass fibres applied by chemical vapour deposition

In this study, the chemical vapour deposition (CVD) technique is used to modify the surface of Li 2 O–ZrO 2 –BaO–SiO 2 glass fibre with Nb 2 O 5 , using NbCl 5 as the precursor. Glass fibres were coated as follows: without thermal pretreatment but followed by air exposure after the reaction with NbCl 5 ; without thermal treatment followed by water hydrolysis, with thermal treatment at 300°C for 2 h and air exposure; and finally, with thermal treatment and hydrolysis in water. The best result was obtained with the fibre chemically modified with Nb 2 O 5 after heat treatment followed by water hydrolysis. This procedure resulted in fibres coated with a homogeneous layer of Nb 2 O 5 without cracks. The fibres were characterised by scanning electron microscopy and energy dispersive X-ray spectroscopy. The fibres were evaluated in the qualitative determination of a mixture of methanol, ethanol and 1-butanol by solid phase microextraction and gas chromatography, yielding better results than those of the fibre coated with Nb 2 O 5 prepared by metallo-organic decomposition.