Preparation, surface morphology, and optical properties of indium(III) oxide nanoparticles by thermolysis of indium–poly(vinyl alcohol) coordination polymer

Abstract

First report on the preparation of well-dispersed, indium(III) oxide (In₂O₃) nanoparticles with 22–35 nm size by polymer thermolysis is presented. Indium–poly(vinyl alcohol) (PVA) coordination polymer films were prepared by ‘solution casting technique’ from the homogeneous aqueous solution of coordination polymer prepared using PVA and indium(III) nitrate as starting materials; subsequently the films were calcined at 550 °C to yield In₂O₃ nanoparticles. Both indium–PVA coordination polymer that served as the precursor and the titled nanoparticles were characterized by Fourier transform-infrared spectroscopy, photoluminescence (PL), powder X-ray diffraction (XRD), transmission electron microscopy, and thermal analysis. Room temperature PL spectra of the prepared indium oxide nanoparticles showed intense blue emissions around 360, 410 and 430 nm, characteristic of indium oxide nanoparticles due to oxygen vacancies. The lower energy PL emission decreases with an increase of indium(III) content in the precursor. The size of the nanoparticles calculated from line broadening of XRD pattern (cubic; JCPDS: 06-0416) was found to be around 24 nm. The average particle size of the synthesized nanoparticles increased with metal ion content in the precursor coordination polymer.

Graphical Abstract

Keywords:

• Thermolysis
• Indium oxide
• Poly(vinyl alcohol)
• Nanoparticles
• Photoluminescence

Acknowledgments

The authors thank Dr K. Kadirvelu, Joint Director Coordinator, DRDO-BU CLS, Bharathiar University, Coimbatore, India, for extending XRD and SEM facilities and Dr D. Bharathimohan, assistant professor in Physics, Pondicherry University, Pondicherry, India, for TEM studies.