Structural, optical, and magnetic properties of pristine and Cr doped WO₃ nanoparticles

Abstract

WO₃ nanoparticles doped with chromium were prepared via acid-assisted precipitation method. These nanoparticles were characterized by XRD, FTIR, Raman, UV-DRS, SEM-EDS and photoluminescence (PL) spectral techniques. The XRD peaks confirmed the monoclinic arrangement with decrease in crystallite size on increasing the dopant concentration. The surface characterizations exposed the doping of chromium ions within the host lattices of WO₃. From the SEM images, it can be noticed that doping changes the morphology of WO₃ nanoparticles. The structure and crystal quality were studied by FTIR and Raman spectra. The absorption spectra reveals that the optical band gap energy is reduced after doping and there is rise in Urbach energies on increasing the Cr concentration. The PL spectra give an insight of increasing numbers of oxygen vacancies in WO₃ after doping. The M–H hysteresis loops reveal that the ferromagnetic character is enhanced on low dopant concentration while at higher dopant concentrations, antiferromagnetism (FM) dominates.

Keywords:

• WO₃ NPs
• chromium doping
• acid assisted precipitation
• ferromagnetism
• Urbach energy

Acknowledgments

The authors are thankful to the Nanotechnology Research Centre (NRC), SRM Institute of Science and Technology, Chennai for providing VSM facility.

Disclosure statement

The authors declare there are no conflicts of interest.