Article

Pramana

, Volume 65, Issue 5, pp 949-958

Structural, electrical and gas-sensing properties of In2O3 : Ag composite nanoparticle layers

  • B. R. MehtaAffiliated withThin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi
  • , V. N. SinghAffiliated withThin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi

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Abstract

The central objective of this study is to investigate (i) size-dependent properties of In2O3 nanoparticles and (ii) the role of metal additives in enhancing the gas sensing response. For this purpose, In2O3 : Ag composite nanoparticle layers having welldefined individual nanoparticle size and composition have been grown by a two step synthesis method. Thermogravimetric analysis, X-ray diffraction and transmission electron microscopy have been used to study the effect of post-synthesis heat treatment on the size and structure of the nanoparticles. A first-time unambiguous observation of sizedependent lowering of transformation temperature has been explained in terms of lower cohesive energy of surface atoms and increase in surface-to-volume ratio with decrease in nanoparticle size. The gas sensing studies of In2O3 as well as the In2O3 : Ag composite nanoparticle layers have been studied as a function of size and composition. In2O3: Ag composite nanoparticle layers with 15% silver show a sensitivity of 436 and response time of 6 s for 1000 ppm of ethanol in air. Ag additives form a p-type Ag2O, which interact with n-type In2O3 to produce an electron-deficient space-charge layer. In the presence of ethanol, interfacial Ag2O reduces to Ag, creating an accumulation layer in In2O3 resulting in increased sensitivity

Keywords

In2O3 nanoparticles Ag nanoparticles gas sensor composite nanoparticles

PACS Nos

07.07.Df 61.46.Df 61.46.-w 81.16.Be