Clad-Modified Fiber Optic Gas Sensing Property Of Pure And Transition Metal Doped Lithium Tetraborate

R. Mohandoss, S. Dhanuskodi
Bharathidasan University, IN

Keywords: gas sensor, fiber optics, evanescent field

Summary:

The pure and transition metal (Mn, Co & Cu) doped lithium tetraborate (LTB) has been prepared by sol-gel method. Lithium hydroxide monohydrate, boric acid and acetates of dopants were used as precursors. The dopant concentration was varied from 0.01 M, 0.03 M and 0.05 M. XRD pattern reveal that the synthesized samples crystallize in tetragonal phase. The particle size of pure sample is in the range of 1 μm and doped samples have the size in the range of 50 – 150 nm. The fiber optic gas sensing setup has been used to study the gas sensing property of pure and transition metal (TM) doped LTB nanoparticles The spectral characteristics of the cladding modified fiber optic sensor coated with pure and LTB: TM are studied for various concentrations of ethanol, methanol and ammonia (50 – 500 ppm). LTB:Co shows appreciable molecular interaction and the sensitivity value is comparable with LTB:Cu. Whereas LTB:Mn shows a low sensitivity value of 18 counts/100 ppm which is having less electronegativity compared with Co and Cu. Based on the above investigations, an efficient room temperature fiber optic ethanol gas sensor can be fabricated using 0.01 M copper doped lithium tetraborate nanoparticles.