lattice Fitzgerald et al 6 report a solubility limit of 5 Azam et al 18 states

Lattice fitzgerald et al 6 report a solubility limit

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lattice: Fitzgerald et al [6] report a solubility limit of 5%, Azam et al [18] states that at 15% no secondary phases are formed, and Kimura et al [5] reports a solubility limit as high as 34%, although they mention the fact that the solubility limit may be pushed upwards through PLD method. Xiao et al report room temperature ferromagnetism for Mn doped SnO 2 thin films, while Gao et al [19] found no RTFM in their studies. In this study, we investigate the structural characteristics of Mn doped SnO 2 (0.02, 0.04, 0.06) synthetized through a simple ethylene glycol assisted sol- gel method. We aim to determine an optimal heat treatment and the solubility limit of Mn ions into the host tin dioxide lattice. Optical properties of doped samples are discussed. 2. Experimental procedure Manganese doped tin dioxide nanoparticles were obtained by a simple ethylene glycol assisted sol-gel method, presented in Fig. 1. The 2%, 4% and 6% at. Mn doped samples were obtained using SnCl 4 (99.99%) and MnCl 2 4H 2 O salts. The salts were mixed in ethylene glycol under magnetic stirring. Concentrated ammonia (25% wt.) was added under stirring drop wise until a neutral pH was reached. The samples were kept under stirring for another 30 minutes, to make sure that the sol is properly formed. All three samples were left to age in laboratory conditions for 14 days. The creamy coloured gels were washed with distilled water in order to remove residual ions like Cl - . The gels were subjected to a thermal treatment carried out at 500 o C for 2 hours. TG/DSC thermograms (20 o C-900 o C) of the Mn doped samples were recorded on a Netzsch STA Jupiter 449 apparatus, using an open alumina crucible, in a dynamic air atmosphere, 20 mL/minute, with a heating rate of 10K/minute. X-ray powder diffraction patterns were obtained with a Shimadzu XRD6000 diffractometer, using Cu K α (1.5406 Å) radiation operating with 30 mA and 40 kV in the 2 θ range 10–70 o . A scan rate of 1 o min -1 was employed. UV-Vis diffuse reflection spectra were recorded between 200-900 nm, on Able Jasco V560 spectrometer, with a scanning rate of 200 nm/minute.
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Mn doped SnO 2 prepared by a sol-gel method 45 Fig. 1 - Synthesis scheme of Mn doped SnO 2 FTIR absorbtion spectra were recorded using a Bruker Tensor 27 device, within 4000-400 cm -1 range. 3. Results and Discussion 3.1. Thermogravimetric analysis The thermograms of the 2% and 6% at. Mn doped gels were obtained in order to determine an optimal heat treatment (figure 2). As expected, both samples exhibit similar thermal patterns, in accordance with the chosen synthesis route. The weight loss around 100 o C, accompanied by an endothermic effect on the DSC curve is attributed to the elimination of physically bond water. Both samples exhibit important weight losses between 110 o C-500 o C, along with exothermic effects on the DSC curve. These losses are explained by the elimination of NH 4 + ions, and the decomposition of the organic remains. The difference in the magnitude of DSC effects can be attributed to the Mn influence on the thermal decomposition. At temperatures higher than 500 o C, both samples are thermally stable in the studied temperature range. Based on the information
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  • Summer '18
  • Peter
  • Oxide, Sol-gel

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