磷酸铁纳米薄膜复合光波导氨气传感元件的制备

将硝酸铁和甲醇、磷酸溶液按一定比例混合后，通过旋涂法制备了磷酸铁（FePO₄）纳米薄膜，测定了匀胶机转速对膜厚及烘干温度对膜厚和折射率的影响，并发现薄膜的烘干温度超过150 ℃时，薄膜的厚度（130 nm）和折射率(1.7)变化不大。将该薄膜固定在钾离子交换玻璃光波导表面，研制出FePO₄膜/K⁺交换玻璃复合光波导。酸碱指示剂溴百里酚兰（BTB）作为敏感试剂，固定在复合光波导表面，研制了BTB膜-FePO₄膜/K⁺交换玻璃复合光波导氨气传感元件。采用自装的光波导气体传感检测系统对不同浓度的氨气进行了检测。结果表明，该传感元件能够检测0.35 mg/m³浓度的氨气，并具有响应（10 s）及恢复（90 s）速度快、可逆性好、连续使用等特点。

Fabrication of Composite Optical Waveguides Based on Thin Films Consisted of Iron Phosphate Nanoparticles and Their Applications as Ammonia Gas Sensor

Thin films consisted of iron phosphate nanopaticles were prepared by spin coating mixed solutions of iron nitrate, methanol and phosphate acid. The effects of coater speed and drying temperature on film thickness and refractive index were studied. It was found that when the thin films were dried at 150 ℃ or higher, the thickness(130 nm) and refractive index(1.7) of the thin films remained nearly unchanged. A composite optical waveguide sensing unit for ammonia vapor was fabricated by spin coating iron phosphate precursor on a single-mode potassium ion exchanged glass followed by spin coating a thin film of a pH indicator dye(bromothymol bule,BTB) onto the composite film. The experimental results show that the sensing unit has a ammonia vapor detection concentration limit of 0.35 mg/m³. It also has unique features such as fast response(10 s), short recovery time(90 s) and good reversibility and reusability.