Compositionally Graded Microstructure for Ag-Fe Nanoparticles

Chandan Srivastava,K V L Sushma

doi:10.1007/bf03353709

Abstract

Abstract Ag-Fe nanoparticles with a highly Ag rich average composition were synthesized by the sonochemical route. Silver-iron system exhibits a wide miscibility gap in the bulk materials. Interestingly, a graded compositional profile along the nanoparticle radius was observed. Regions at and near the surface of the nanoparticle contained both Ag and Fe atoms. The composition got relatively deficient Fe towards the center of the particle with particle core made up of pure Ag. Alloying of Ag and Fe is confirmed by the absence of diffraction signal corresponding to pure Fe phase and presence of a paramagnetic phase in nanoparticles containing a diamagnetic (Ag) and ferromagnetic (Fe) elements.

Highlights

Scientific and technological research endeavors in nanoscience and nanotechnology have gained significant momentum in the recent years
The growing interest is primarily due to two important incentives; (a) tunable functional properties and (b) realization of microstructures that cannot be obtained in the bulk systems with similar compositions and under similar conditions
Paramagnetic character has been reported for a diamagnetic (Ag)-rich, solid solution AgNi system which is similar to the Ag-Fe system both with respect to the magnetic nature of the component element atoms and with respect to the immiscibility in the bulk state [15].The ferromagnetic component with an extremely low value of the saturation magnetization (∼0.001 emu/g) and coercively (∼30 Oe) can be due to the presence of very small amount of ferromagnetic Ag-oxide impurity on the surface of the Ag-Fe nanoparticles

Summary

Introduction

Scientific and technological research endeavors in nanoscience and nanotechnology have gained significant momentum in the recent years. With respect to the novel microstructures, one significant observation has been the formation of solid solution between atoms with a large difference in sizes (>14%) and a high positive enthalpy of mixing [1,2]. Such component atoms do not form a single phase solid solution in bulk for certain or overall composition ranges. A nano-sized particle in which one of the component element atoms is present in a relatively lower amount as solute can possibly retain a thermodynamically stable single phase solid solution microstructure from the synergetic effect of nano size and lower positive enthalpy of mixing value. The magnetic hysteresis loop for the as-synthesized nanoparticles was obtained using a Lakeshore Vibrating Sample Magnetometer (VSM)

Result and discussion

Conclusion