Microwave assisted synthesis of Sn(1−x)CoxO2 nanoparticles: effect of impurity phase formation on structural, optical and electrochemical properties

Abstract

Nanocrystalline Sn (1-x) Co x O 2 (x = 0, 0.01, 0.03 and 0.05) nanoparticles have been synthesized under microwave irradiation using oxalic acid (H 2 C 2 O 4 ) as reducing agent. X-ray diffraction studies show that the prepared nanoparticles are crystalline with tetragonal crystal system and with few additional phases, which is further supported by Raman spectroscopy. The variation in molar concentration of Co 2? ions had a significant effect on size and morphological aspects which is evident from high resolution microscopic images. The emission owing to band edge position, recombination with V o ?? centers and recombination with shallow level defects were observed from the Photoluminescence spectrum. The existence of room temperature ferromagnetism has been clearly observed using magnetization hysteresis measurements and the magnetic moments are found to decrease with the increased cobalt ions concentration. The decrease in charge carriers that arises due to the formed impurity phases and its significant effect on electron transfer capability have been discussed with the assistance of cyclic voltammetry. This study possibly will bring better insight for understanding the effects of doping concentration, formation of impurity phases and explicate the consequences of them on various properties of nanostructured materials.

Ni-Doped SnO2 Nanoparticles for Sensing and Photocatalysis

“…These defects are accountable for the A 1g peak shift (Figure S4b) and the generation of additional vibrational bands in the spectra. The bands located at 248, 306, 341, 505, 543, and 693 cm –1 correspond to the E u (2) TO, E u (3) TO, E u (2) LO, A 2u TO, B 1u (3), and A 2u LO modes. , …”

“…The normal vibrational modes of the rutile tetragonal correspond to the E u (2) TO, E u (3) TO, E u (2) LO, A 2u TO, B 1u (3), and A 2u LO modes. 22,23 The elemental compositions and oxidation states of SN0 and SN7 were investigated by XPS (Figure 2a−f). Figure 2a displays the spectra of SN0 and SN7, confirming the presence of Sn, O, and Ni elements.…”

Improved Room-Temperature Ferromagnetism in Nd-Doped SnO2 Nanostructures through Defect Engineering

“…Dilute magnetic semiconductors (DMSs) have received a great deal of attention recently because of the opportunity to employ the charge and spin features of electrons in the field of spintronics. − DMS systems possess both semiconducting and magnetic properties, enabling them to be the suitable materials for technological applications. , The essential prerequisite for the practical application of DMS is to exhibit room-temperature ferromagnetism (RTFM), which can be easily observed in oxide nanomaterials. , The origin of induced magnetism in these systems is still a controversial subject. Some investigations have suggested that the incorporation of suitable dopants in the undoped semiconducting structure plays a crucial role in making them ferromagnetic, , whereas a few other studies have reported that mediated defects such as oxygen vacancies (V o ) are accountable for the occurrence of this phenomenon. − Oxide semiconducting nanomaterials such as SnO 2 , ZrO 2 , TiO 2 , ZnO, and CeO 2 have attracted much interest from the research community because of their various potential applications. − Among them, SnO 2 nanomaterials have been used in gas sensing, transparent conducting electrodes, spintronics, optoelectronics devices, flat-panel displays, and Li-ion batteries because of their unique features, such as high optical transparency, rich oxygen vacancies, good electrical conductivity, and better thermal and chemical stabilities compared with other nanomaterials. − SnO 2 (n-type semiconductor) has a large energy gap ( E g = 3.6 eV). Its space group is P 4 2 / mnm , and it has a tetragonal rutile crystal lattice.…”