Effect of particle size on Curie temperature and coercivity of Gadolinium silicide (Gd5Si4)

POSTER

Abstract

Nanoparticles (NP) exhibit different properties from their parent bulk materials due to finite size & surface effects. In this study, size dependent magnetic properties of Gadolinium Silicide (Gd5Si4) NP from ball-milled ingot are investigated. NP were size separated into 8 fractions using time sensitive sedimentation in an applied dc magnetic field. SEM image analysis shows average NP sizes of 700nm,615nm,560nm,470nm,342nm,223nm,84nm and 82nm for the 8 corresponding fractions. XRD analysis indicates that Gd5Si4 is the major phase and Gd5Si3 is the minor phase present in all fractions. VSM measurements reveal that as the NP sizes decreases, the transition temperature (Tc) of Gd5Si4 is reduced from 316K to 312K and to 310K, while the ordering of the minor phase is independent of the NP sizes with stagnant Tc at 110K. The M-H curves at 300K exhibits ferromagnetic behavior descending to paramagnetic across fractions. Coercivity (Hc) obtained from hysteresis plots show that Hc increases with decrease in NP size across fractions until it reaches critical single-domain size & then decreases toward zero where it becomes superparamagnetic.

Presenters

  • Shivakumar Hunagund

    Dept. of Mechanical and Nuclear Engineering, Virginia Commonwealth Univ

Authors

  • Shivakumar Hunagund

    Dept. of Mechanical and Nuclear Engineering, Virginia Commonwealth Univ

  • Ahmed El-Gendy

    Dept. of Physics, University of Texas at El Paso

  • Shalabh Gupta

    Division of Materials Science and Engineering, Ames Laboratory

  • Vitalij Pecharsky

    Iowa State University, Ames Laboratory, U.S. Department of Energy, and Department of Materials Science and Engineering, Iowa State University, Materials Sceince and Engineering, Ames Laboratory, Division of Materials Science and Engineering, Ames Laboratory, Ames Laboratory

  • Shane Harstad

    Dept. of Mechanical and Nuclear Engineering, Virginia Commonwealth Univ

  • R. L. Hadimani

    Virginia Commonwealth Univ, Department of Mechanical and Nuclear engineering, Virginia Commonwealth University, Virginia commonwealth University, Dept. of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Dept. of Mechanical and Nuclear Engineering, Virginia Commonwealth Univ