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

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.