Room-temperature ferromagnetism of sol-gel-synthesizedSn1−xFex57O<

Abstract

We report unusual observations in the magnetic behavior of Sn 1−x 57 Fe x O 2−␦ powders prepared by a sol-gel method. Mössbauer spectra showed three different sites for those irons in the SnO 2 lattice. The samples seem to exhibit many sources of ferromagnetism, and the dominance of one of them greatly depends upon the synthesis conditions. In one sample, prepared using citric acid solution of metal Fe and annealed at 500°C for two hours, we observed magnetization, but its room temperature Mössbauer spectrum did not show any magnetic component, suggesting that the ferromagnetism could not have originated from the iron ions but from magnetic defects. In another sample prepared from chloride acid solution of Fe 2 O 3 and annealed at 600°C for six hours, a large magnetization and a sextet with broad lines were observed and the ferromagnetism was ascribed to iron impurities. In another sample prepared from citric acid solution of metal Fe but annealed at 650°C for two hours, we observed an intensive magnetic sextet with sharp lines but small magnetization, suggesting the presence of hematite doped with tin.

Fe-doped SnO 2 nanopowders obtained by sol–gel and mechanochemical alloying with and without thermal treatment

“…Oxide diluted magnetic semiconductors, ODMS, in which nonmagnetic oxide semiconductors are doped with just a low percent of transition metal ions are expected to play an important role in the development of semiconductor spintronics [1,2]. Transition metal doped SnO 2 belong to these classes of materials [3][4][5]. Several synthetic methods to produce them have been explored, but many methods have the drawback of producing impurity phases and/or magnetic ion clustering.…”

Characterization of ⁵⁷Fe Implanted and Annealed SnO₂ (3 % Sb) Films by Depth Selective Conversion Electron Mössbauer Spectroscopy (DCEMS)

“…[1][2] We have reported different types of magnetic source in case of Fe doped SnO 2 powders, prepared by sol-gel method and post annealing 3 , and also the phonon density of states (DOS) of rutile type structures of SnO 2 and TiO 2 . 4 The dilution and clustering of doping Fe species can be estimated by Mössbauer spectra and phonon DOS.…”

“…In the latter case, the magnetization disappeared by annealing for long time. 3 It is clear that defects in DMS can also contribute to enhance the saturation magnetization.…”

Magnetic Properties and Oxygen Defects of Dilute Metal Doped Tin Oxide Based Semiconductor

“…(b) Mössbauer spectra of the sample annealed at 500 °C, (c) the sample annealed at 600 °C; and (d) the sample annealed at 650 °C. [13] As shown in Figure 2, the saturation magnetization (Ms) of the sample heated at 500 °C for 2 hours decreases by annealing at 500 °C further for 4 hours. The oxygen defects are considered to be repaired by annealing for long time.…”

“…[11] In this review article, 57 Fe Mössbauer analytical results and magnetic properties of SnO2 based materials doped with diluted Fe ions are introduced together with theoretical results obtained by ab initio calculation for configurations of substituted Fe and oxygen defects of Fe doped SnO2. [12] MAGNETIC PROPERTIES OF Fe DOPED Sn OXIDE POWDER Fe Doped SnO2 [13] 10 at % Fe doped SnO2 powder was prepared by a sol-gel method and the thermal decomposition. The relationship between magnetization curves and annealing conditions is shown in Figure 1 (a).…”