Synthesis and Characterization of Magnetic Iron Sulfide Nanowires

Abstract

equipped with a 150 lines mm ±1 grating and registered by an optical multichannel analyzer (OMA, Hamamatsu Photonics, PMA50 Synthesis and Characterization of Magnetic Iron Sulfide NanowiresBy Manashi Nath, Amitava Choudhury, Asish Kundu, and C. N. R. Rao* A variety of inorganic nanowires have been synthesized in the last three to four years.[1] Among these, magnetic nanowires are of interest because of their potential applications in magnetic recording and other areas. Nanowires and nanorods of magnetic metals, such as Fe, Co, and Ni, [2] and their alloys [3] have been prepared by employing template-directed synthesis. Although there are reports of nanotubes, nanorods, and nanowires of several metal chalcogenides, [4,5] oxides, [6] and nitrides [1,6] there is no report to date on iron sulfide nanowires, possibly because of the inherent difficulty in the synthesis and control of stoichiometry of these materials. The Fe±S system has a complex phase diagram, with broad range of compositions of Fe 1±x S (pyrrhotite) phases [7] occurring between FeS and FeS 2 , showing interesting magnetic [8±10] and electrical properties.[11] Fe 7 S 8 is a well-defined phase in this region,showing ferrimagnetism with T N = 600 K. [9] We deemed it important to synthesize iron sulfide nanowires by virtue of their interesting chemistry and magnetic properties. In this communication, we report the first successful synthesis of semiconducting nanowires of Fe 1±x S (x » 0.12, 0.09), of which the Fe 0.88 S (Fe 7 S 8 ) nanowires are ferrimagnetic, showing magnetic hysteresis at room temperature. In order to synthesize Fe 1±x S nanowires, a hybrid composite (I) with ethylenediamine was first prepared by solvothermal procedure (see Experimental). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the composite I showed the presence of a high yield of lengthy nanowires with diameters in the range of 80±150 nm and lengths of several micrometers as shown in Figure 1. The infrared (IR) spectrum showed characteristic peaks of the amine, although the bands due to C±N and N±H stretching frequencies were considerably shifted towards lower values due to the bound nature of the amine. Energy dispersive X-ray (EDX) analysis of several samples of I carried out over different regions of each sample gave an average Fe/S ratio of Fig. 1. a) SEM image of the organic±inorganic composite, Fe 1±x S(en) 0.5 , I. b) Low-magnification TEM image of composite I. Apart from nanowires, some layer-rolled kind of structures are also observed (as seen in the center of the image).

Synthesis of ternary Ni1−Fe S single crystalline nanorods

“…Many works have shown that EN solvent can function as molecular template directing the growth of nanomaterials of transition metal sulfides by chelating with metal ions including Zn 2+ , Cd 2+ , Ni 2+ and so on [11][12][13]. There are many phases of iron sulfides and some are important magnetic and optoelectrical materials with potentials in storage and solar cell [14,15]. Some high temperature physical or chemical vapor routes to FeS 2 films or nanostructures [15][16][17], low temperature solvothermal technique has been employed to synthesize iron sulfide nanomaterials including Fe 7 S 8 and Fe 1Àx S nanowires [14].…”

“…There are many phases of iron sulfides and some are important magnetic and optoelectrical materials with potentials in storage and solar cell [14,15]. Some high temperature physical or chemical vapor routes to FeS 2 films or nanostructures [15][16][17], low temperature solvothermal technique has been employed to synthesize iron sulfide nanomaterials including Fe 7 S 8 and Fe 1Àx S nanowires [14].…”

Magnetic‐Field‐Induced Phase‐Selective Synthesis of Ferrosulfide Microrods by a Hydrothermal Process: Microstructure Control and Magnetic Properties

“…ethylenediamine) nanowires, which were obtained by a solvothermal method in ethylenediamine media. [25] Herein is reported the selective synthesis of cubic Fe 3 S 4 , orthorhombic FeS 2 , and cubic FeS 2 by using an alternative sulfur precursor and with the aid of a magnetic field under hydrothermal conditions. The successful access to metastable phase greigite is consistent with the fact that greigite is stable over periods of several million years in nature and also exists as a sediment.…”

Tellurium microtubes synthesized by thermal evaporation method

“…In recent years low-dimensional nano and micromaterials in the tube, rod, wire and belt form have been the focus of extensive research owing to their novel optical, electrical, magnetic and catalytic properties, which are different from those of bulk materials [1][2][3][4][5][6]. Moreover, these materials have shown interesting applications in the emerging area of optoelectronic devices.…”