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Structural, optical and humidity sensing studies of nickel oxide (NiO) nanoparticles: effect of calcination temperature

P. K. Ingalagondi, N. C. Horti, Y. T. Ravikiran, M. Prashantkumar, and B. G. Kumaraswamy

Department of Physics, Government First Grade College for Women, Davanagere, India



Received: 19 September 2023  Accepted: 5 January 2024


Herein, nickel oxide (NiO) nanoparticles have been synthesized through a simple co-precipitation route. The obtained samples were calcinated at two different temperatures (500 °C and 900 °C) using a muffle furnace. The structural, morphological, and optical properties of nanoparticles were examined by X-ray diffraction, Scanning electron microscopy, Energy dispersive X-ray, Fourier infrared spectroscopy and UV–Vis absorption spectroscopy. The resistive type humidity sensing behavior was studied through a locally fabricated experimental setup. The XRD pattern of the samples revealed that the as-prepared sample appeared in the β-Ni(OH)2 hexagonal phase, and the samples calcinated at 500 °C and 900 °C, are crystallized in the cubic structure of NiO phase. The formation of highly agglomerated and irregular shaped particles was noticed form SEM images. FTIR analysis confirmed the formation of β-Ni(OH)2 and pure NiO phases, which is supported by EDX analysis. UV–Vis absorption studies showed a red shift of absorption edge and a varying band gap of NiO nanoparticles with calcination temperature due to the crystal growth and increase in crystallinity of samples. The sample calcinated at 900 °C has shown a humidity sensitivity of 0.3 K-cm/% RH, a limit of detection of 7% RH and good linearity with a correlation co-efficient of 0.995.

Graphical abstract

Keywords: Nickel oxide; Co-precipitation method; Calcination temperature; Optical properties; Humidity sensing

Full paper is available at

DOI: 10.1007/s11696-024-03314-8


Chemical Papers 78 (5) 3331–3342 (2024)

Friday, June 21, 2024

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