Generalized Synthesis ofEAs [E= Fe, Co, Mn, Cr] Nanostructures and Investigating Their Morphology Evolution

P Desai,M Nath,Nikitaa Ashokan

doi:10.1155/2015/362152

Abstract

This paper illustrates a novel route for the synthesis of nanostructured transition metal arsenides including those of FeAs, CoAs, MnAs, and CrAs through a generalized protocol. The key feature of the method is the use of one-stephot-injectionand the clever use of a combination of precursors which are low-melting and highly reactive such as metal carbonyls and triphenylarsine in a solventless setup. This method also facilitates the formation of one-dimensional nanostructures as we move across the periodic table from CrAs to CoAs. The chemical basis of this reaction is simple redox chemistry between the transition metals, wherein the transition metal is oxidized from elemental state (E0) toE3+in lieuof reduction of As3+to As3−. While the thermodynamic analysis reveals that all these conversions are spontaneous, it is the kinetics of the process that influences morphology of the product nanostructures, which varies from extremely small nanoparticles to nanorods. Transition metal pnictides show interesting magnetic properties and these nanostructures can serve as model systems for the exploration of their intricate magnetism as well as their applications and can also function as starting materials for the arsenide based nanosuperconductors.

Highlights

Metal pnictides are an important class of compounds exhibiting interesting electronic, semiconducting, optical, and magnetic properties [1]
After conducting several blank experiments without the metal precursors an appropriate temperature range was selected for injecting the metal carbonyls
It can be expected that, during initial stage of the reaction, ligand exchange takes place as soon as Ex(CO)y is added to the mixture of TPA and HDA as seen in Figure 1, whereby the CO ligand is displaced by the As(C6H5)3 to form an intermediate complex [(C6H5)3AsEx(CO)y−1] with generation of free CO

Summary

Introduction

Metal pnictides are an important class of compounds exhibiting interesting electronic, semiconducting, optical, and magnetic properties [1]. CrAs is a half-metallic ferromagnet with a band gap of 1.8 eV [7] while MnAs shows ferromagnetic interactions [8] Such ferromagnetic semiconductors are important in the field of spintronics. It was found that the ferromagnetic order is more stable than the antiferromagnetic state for VAs, CrAs, and MnAs, the greatest energy gain being predicted for CrAs [10]. Some of these transition metal pnictide belong to the structure type of filled skutterudite (typically Co3As) which shows promise as thermoelectric materials [11].

Methods

Results

Conclusion