Sol–gel synthesis, structural, morphological and optical properties of Se-doped SnO 2 nanoparticles Suresh Kumar 1 • Princy Chauhan 1 • Virender Kundu 1 Received: 8 November 2015 / Accepted: 25 December 2015 Ó Springer Science+Business Media New York 2015 Abstract In this paper, the preparation of Se-doped SnO 2 nanoparticles (NPs) and their structural, morphological and optical properties have been reported. Se-doped SnO 2 NPs have been prepared from the precursors containing tin chloride dihydrate and selenium dioxide in the presence of ammonium hydroxide as capping agent via sol–gel method. Three samples of Se-doped SnO 2 NPs with selenium con- centration of 0.05, 0.10, and 0.15 wt% have been prepared and calcined at 500 °C for 3 h. The physical and chemical properties have been studied by SEM, EDS, XRD and UV– Vis spectroscopy. The SEM study reveals that the size of the nanoparticles is not uniform and the particles are agglomerated. The EDS study confirms the doping of Se in the SnO 2 NPs. The XRD study reveals the formation of nanoparticles with high crystallinity and broadened width. The minimum size of the nanoparticles obtained is found within the range of 12–17 nm. The optical band gap of Se- doped SnO 2 NPs of 0.05, 0.10, and 0.15 wt% Se have been found 3.21, 2.98 and 2.90 eV respectively. It is found that the band gap of Se-doped SnO 2 NPs is decreased from 3.64 eV of pure SnO 2 NPs. 1 Introduction In the present era of nano-regime, nanomaterials show potential tools for scientific innovations. Because of their unique electronic, optical, catalytic and magnetic proper- ties; the applications of nano-materials such as nano- particles (NPs) have increased in many fields like medi- cine, electronics, optoelectronics, sensors and photo catal- ysis [1–4]. Metal oxide NPs such as ZnO, TiO 2 , SnO 2 were widely studied for their potential application in the field of electronics, sensors, optoelectronic, photovoltaics, photo- catalysis etc. [5–7]. Among theses, SnO 2 is an important material that shows an n-type character due to oxygen vacancies but can be made both p-type and n-type semi- conductor by doping with foreign impurities and possesses high electrical conductivity [5, 6, 8]. Currently, the research on tin oxide (SnO 2 ) NPs is of great interest amongst scientific community because of its remarkable applications in various scientific fields. Tin oxide (SnO 2 ) NPs can be extensively used as a photo catalyst and as biological agents to start the redox reactions due to their physiological properties because of its size-induced effects [9]. Tin oxide (SnO 2 ) NPs possesses wide band gap of 3.6 eV, non-stoichiometric behavior and high excitation binding energy thus have potential applications in current technologies such as solar cells, transistors, gas sensors and catalysis [4, 5, 8]. The study on doped-SnO 2 NPs is still under investigation to know enhanced properties of SnO 2 NPs. Ahmed et al. [10] demonstrated that increasing alu- minium (Al) content in SnO 2 changes its conducting properties from n-type to a p-type. Arago ´n et al. [11] and Lavanya et al. [12] reported the fabrication and study of chromium (Cr)-doped SnO 2 NPs which revealed that the particle size of SnO 2 NPs is reduced with chromium (Cr) and the increase in chromium content increases oxygen vacancies. Sharma et al. [13] studied and demonstrated the iron and nickel doped SnO 2 nano-crystalline powders at room temperature that have shown the ferromagnetism behavior. Wang et al. [4] presented Li-doped SnO 2 NPs and observed red-shift in the band gap and ferromagnetism. & Suresh Kumar sawan2k2@yahoo.co.in 1 Department of Electronic Science, Kurukshetra University, Kurukshetra 136119, India 123 J Mater Sci: Mater Electron DOI 10.1007/s10854-015-4263-x