Structurally enriched aliovalent Cd2+-doped SnO2 nanocrystals and their physicochemical investigations

In the present study, pristine and Cd2+ modified SnO2 compositions [Sn(1−y)CdyO2, where y = 0, 0.05, and 0.10] were synthesized by co-precipitation technique. Structural studies were carried out by X-ray diffraction (XRD) analysis which revealed that all the compositions exhibited tetragonal rutile-type crystal structure with P42/mnm space group with high purity (absence of secondary phases). FTIR spectra confirmed the formation of pristine and Cd2+ modified SnO2 nanocrystals as bend at 560 cm−1 attributed to Sn–O–Sn stretching vibrations. UV–Vis optical spectra displayed a sharp peak at ~ 304 nm and ~ 311 nm belonging to UV region (200–400 nm) and a small hump at 561 nm corresponding to the visible region for Cd2+-doped compositions. FESEM micrographs depicted the nano-scale formation of pristine and Cd2+ modified SnO2 nanocrystals calcined at 600 °C and showed that grain size increased from 45.66 ± 1.2 nm to 60.27 ± 2.7 nm with increasing Cd2+ concentrations. HRTEM images confirmed the tetragonal crystallinity of as-synthesized nanocrystals as fringes attributed to (110) plane orientation with d-spacing ~ 0.34 nm exactly matched with XRD studies. Dielectric analysis showed that dielectric constant decreased with increasing Cd2+ in the compositions and I–V curves illustrated linear or ohmic behavior with diminishing values of resistances for higher Cd2+ concentrations.