Optical nonlinearities of centrosymmetric pure and cerium doped calcium tungstate dumbbell shaped nanoparticles

Abstract

An investigation was performed on the nonlinear optical behavior of pure and cerium (Ce3+) doped calcium tungstate (CaWO4) nanoparticles synthesized by hydrothermal method. The scheelite tetragonal structure was confirmed using X-ray diffraction. The morphological transformation from spherical to dumbbell-shaped particles was evidenced by FESEM micrographs augmented from the TEM images. Different vibrational modes obtained from Raman spectra confirms the presence of Ca–O–Ca and W–O–W functional groups. The Photoluminescence response was observed in the blue green region at an excitation wavelength of 325 nm. With the utilization of UV–Visible DRS spectroscopy the variations in the optical band gap was calculated. The valence state and chemical composition of the elements along with their binding energies has been calculated using XPS. The magnetic behavior of CaWO4 in its doped and undoped state is examined through VSM analysis. A measure of the nonlinearities with emphasis to the mechanism of Reverse Saturable Absorption (RSA) supported by open and closed aperture data is recorded. Kerr nonlinearity, Two photon absorption β and third order nonlinear susceptibility χ(3) were also calculated. The present work provides an insight on the dependence of linear and non-linear optical properties of CaWO4 with dopant concentration.