Optical properties and sensing applications of lithium iron phosphate thin films

• Published in: Thin solid films 2012-07, Vol.520 (19), p.6250-6255
• Main Authors: Nizamidin, Patima, Yimit, Abliz, De Wang, Ji, Itoh, Kiminori
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Detection; Exact sciences and technology; Gas sensor; General equipment and techniques; Growth from solutions; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Iron; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Lithium; Lithium iron phosphate; Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Nanostructure; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Optical waveguide; Optical waveguides; Phosphates; Physics; Refractive index; Sensors; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Sol–gel deposition; Thin films; Xylene
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2012.05.024

A composite optical waveguide sensor, consisting of lithium iron phosphate (LiFePO4, LFP) as the sensing material, was constructed and utilized for the detection of volatile organic compound gases. Nano-LFP powder was prepared via the hydrothermal method and was subsequently utilized in a dip-coating procedure for the fabrication of LFP thin films. The effect of heat treating temperature on the refractive index of the thin films was studied. A glass optical waveguide gas sensor was fabricated by coating an LFP thin film on the surface of single-mode tin-diffused glass optical waveguide. The sensor was found to exhibit a linear response to xylene in the range of 50–1000ppm, with response times of less than 5s. ► LiFePO4 was selected as sensing material for xylene detection. ► Refractive index of LiFePO4 thin films increases with annealing temperature from 120 to 450°C. ► LiFePO4 optical waveguide sensor easily detects 50ppm of xylene gas with response