Effect of Precursor Salt on FeP Nanoparticle Formation
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DD5.9.1
Effect of Precursor Salt on FeP Nanoparticle Formation Susanthri C. Perera and Stephanie L. Brock* Department of Chemistry, Wayne State University, Detroit, MI, 48202. ABSTRACT The formation of single phase FeP nanocrystals has been achieved by the reaction of Fe(III) salts (iron(III)acetylacetonate (Fe(acac)3) and iron(III)chloride (FeCl3)) with tris(trimethylsilyl)phosphine in trioctylphosphine oxide (TOPO)/trioctylphosphine (TOP) at elevated temperatures. The sizes of nanoparticles formed differ markedly depending on the initial iron salt used. Use of Fe(acac)3 always resulted in comparatively bigger particle formation (~5 nm) while FeCl3 forms much smaller particles (~1 nm) as confirmed by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM).
INTRODUCTION Over the past several years, there has been sustained interest in the preparation and characterization of particles with dimensions ranging from 1-100 nm (nanoparticles). Such materials provide an opportunity to observe the evolution of physical properties as a function of particle size [1,2]. Transition metal pnictides (pnicogen = group 15 element) are a class of compounds that demonstrate a diverse range of physical properties [3] including ferromagnetism, magnetoelastic and magnetooptical properties, and superconductivity. Although nanoparticulate analogs might be expected to exhibit novel, size-dependent magnetic and electronic properties, they remain largely unstudied The focus of this study is the preparation and study of size dependent properties of iron phosphide nanoparticle systems, beginning with FeP. Bulk FeP has metallic properties and demonstrates a helical ordering of spins with a net antiferromagnetic interaction and a TN of 125 K [4]. The effect of crystallite size on the magnetic properties of this phase has not been reported, nor the preparation of discrete, phase pure nanoparticles. A range of methods [5] has been employed in the successful synthesis of main group semiconducting pnictide/chalcogenide nanoparticle systems involving slow [6] and rapid nucleation [7] and growth in coordinating media. Herein we report the applicability of the de-silylation strategy for the production of FeP nanoparticles. This route is formally a non-redox process, permitting the targeting of particular phases by controlling the oxidation state of the transition metal precursor.
EXPERIMENTAL DETAILS The synthesis of Fe phosphide nanoparticles has been undertaken according to the stoichiometric reaction shown in Equation 1, which involves simple metathesis reactions between Fe3+ salts and tris(trimethysilyl)phosphine in trioctylphosphine oxide (TOPO)/trioctylphosphine (TOP). This technique enables production of nanoparticles with surfaces that can be further functionalized to obtain different physical/chemical properties.
DD5.9.2
FeX3 + P(SiMe3)3 → FeP + 3 XSiMe3 X = Cl, acac (acetylacetonate) (1) All manipulations involving iron salts and phosphines were performed in anhydrous reagents under inert atmospheric conditions using a
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