Effect of gadolinium doping on the Structural, magnetic, Electrical, Optical, and elastic properties of magnetite nanoparticles.

• The co-precipitation method was used for the synthesis of Fe 3-x Gd x O 4 nanoparticles. • XRD results showed that the prepared particles have good crystallinity and face-centered cubic spinel structure. • TEM micrographs revealed the formation of rod-like structures along with round-shaped particles found with gadolinium doping. • The saturation magnetization and coercivity increased with increasing the Gd3+ doping concentrations. • Electrical resistivity is found to decrease two-fold with Gd3+ doping. In the present study, Fe 3-x Gd x O 4 nanoparticles (with × varying from 0 to 0.1) were synthesized using the co-precipitation method. Lattice constant and X-Ray density were determined using X-Ray Diffraction (XRD). Transmission Electron Microscopy (TEM) study revealed the formation of rod-like structures along with round-shaped particles after gadolinium doping. Selected Area Electron Diffraction (SAED) showed good crystallinity of nanoparticles. Elastic constants were calculated using FTIR and XRD data. The study of the vibrating sample magnetometer (VSM) revealed that the saturation magnetization increased with Gd3+ doping from 54.3 emu/g at x = 0.0 to 84.8 emu/g at x = 0.04. Coercivity also increased with Gd3+ doping. The value of resistivity has been observed to be 4.02 × 106 Ohm-cm for undoped samples using Keithley's two-probe method. The dc resistivity of doped samples has been decreased by two orders of magnitude as compared to the undoped sample. UV–Vis spectroscopy has been used to calculate the band gaps with the help of Tauc plots. The band gap for the undoped particle is 2.46 eV which decreases with Gd3+ doping till 2.08 eV for x = 0.03. Band gaps are correlated to electrical behavior. Young modulus, Bulk modulus, Rigidity modulus, and Poisson's ratio were found to enhance with gd doping beyond x = 0.03. The increase of elastic constants with doping indicates the strengthening of interatomic bonding. These nanoparticles could have applications as optoelectronic and magnetoelastic sensors. [ABSTRACT FROM AUTHOR]