Physicochemical investigations of structurally enriched Sm3+ substituted SnO2 nanocrystals

The present study portrays structural, magnetic, electrical, optical and electronic characteristics of polycrystalline pristine and aliovalent Sm³⁺ modified Tin oxide (SnO₂) nanocrystals [Sn_(1−x)Sm_xO₂ nanocrystals, where x = 0, x = 0.05, and x = 0.10] were synthesized using conventional sol–gel route. X-ray diffractogram showed rutile-type tetragonal crystallinity [space group P4_2/mnm] for all the samples. Microstructural investigations depicted well-interlinked grains and it was observed that average grain size increases with Sm³⁺ substitution in the crystal framework of SnO₂. HRTEM images also confirmed the tetragonal rutile symmetry for all the compositions. FTIR spectra validated the phase pure synthesis and formation of Sm³⁺ substituted SnO₂ nanocrystals as bend at 470 cm⁻¹ attributed to the Sn/Sm–O vibrations. Magnetic measurements depicted that Sm³⁺ modified compositions showed room temperature magnetism with low coercivity and retentivity, while pristine SnO₂ nanocrystals illustrated diamagnetism at higher magnetic field and defect-assisted ferromagnetism at low fields. The maximum value of dielectric constant (ε′) was observed for pure SnO₂, and dielectric constant (ε′) decreases with increasing Sm³⁺ concentration. I-V curves showed non-linear behavior for all the samples and the maximum resistance was found for pure SnO₂ nanocrystals. The incorporation of aliovalent rare-earth Sm³⁺ ion in SnO₂ crystal matrix induces ferromagnetism in the system, which makes it dilute magnetic semiconductor for magneto-or spin electronics.