NO_2 Sensing Properties of Porous In_2O_3-based Powders Preapred by Utilizing Ultrasonic-spray Pyrolysis Employing PMMA Microsphere Templates: Effects of the Size of the PMMA Microspheres on their Gas-sensing Properties

摘要

PMMA microspheres were synthesized in distilled water by ultrasonic-assisted emulsion polymerization. The average particle size of PMMA microspheres was dependent markedly on the kind of surfactant used. Porous (pr-) In_2O_3 powders were prepared by ultrasonic-spray pyrolysis of In(NO_3)_3 aqueous solution containing the PMMA microspheres synthesized. The NO_2 response of pr-In_2O_3 was much larger than that of conventional In_2O_3 powder prepared by the similar technique employing PMMA-free In(NO_3)_3 aqueous solution. The introduction of controlled macroporous structure into the powder of the sensor material was found to be effective for improving NO_2 response properties.