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Structural and optical properties of pure ­SnO2 and ­V2O5/SnO2 nanocomposite thin films for gas sensing application V. Janakiraman1 · V. Tamilnayagam2 · R. S. Sundararajan1 · S. Suresh3   · C. S. Biju4 Received: 16 May 2020 / Accepted: 25 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020

Abstract In this study, pure S ­ nO2 and V ­ 2O5/SnO2 nanocomposite thin film N ­ H3 sensors with varying V ­ 2O5 contents were successfully prepared by spray pyrolysis method. The prepared thin films were characterized by X-ray diffraction, Field emission scanning electron microscopy, Energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, stylus profilometry and Ultra violet–Visible and transmittance spectroscopies. ­NH3 gas sensing property was also studied. XRD results suggested that all the thin films exhibited a tetragonal rutile crystal structure, while the average crystallite size increases with ­V2O5 content. FESEM images of the thin films showed the presence of both nano and micro-sized grains in the range ~ 53–194 nm. EDX spectra confirmed the inclusion of V ­ 2O5 into the S ­ nO2 matrix. The vibrational bands associated with the thin films were verified from the FTIR spectra. Thickness measurements revealed that the thickness increases with V ­ 2O5 content. Change in transparency and bandgap narrowing were also noticed from the transmittance and UV–Vis spectra. N ­ H3 gas sensing measurements suggested that the transient resistance of V ­ 2O5/SnO2 thin film was lower than pure S ­ nO2. Further, in the operating temperature 300 °C and 100 ppm NH3 gas, the sensor response of ­V2O5/ ­SnO2 thin film (99.13) is found to be higher than pure S ­ nO2 thin film (92.34). Also, the response and recovery times of pure S ­ nO2 thin film (30 and 44 s) are lower than V ­ 2O5/SnO2 thin film (39 and 180 s). These results indicate that ­V2O5/SnO2 thin film could serve as a suitable material for ­NH3 gas sensing application.

1 Introduction Ammonia ­(NH3) is considered as one of the key precursors to synthesize various materials in chemical industries [1]. It is a colourless gas which could stimulate eye and nose, * V. Janakiraman [email protected] * S. Suresh [email protected] * C. S. Biju [email protected] 1



PG & Research Department of Physics, Government Arts College (Autonomous) (Affiliated to Bharathidasan University), Kumbakonam, Tamil Nadu 612002, India

2



Department of Physics, A.P.A. College of Arts & Culture, Palani, Dindigul, Tamil Nadu, India

3

Departments of Physics, Saveetha Engineering College (Autonomous), Thandalam, Chennai, Tamil Nadu 602105, India

4

Department of Physics, Malankara Catholic College, Mariagiri, Kaliakkavilai, Tamil Nadu 629153, India





and consequently vomit and headache occurs. Therefore an attractive method to sense the presence of ­NH3 in the atmosphere is much essential in the field of environmental measurement and control. Semiconductor-based sensors have been extensively investigated to detect gas components eve