Thermopower,specific heat and magnetic properties in FeSi2 nanoparticles

• Main Authors: Yu-Hao Wang, 王宇豪
• Other Authors: Y.Y. Chen
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/02994040106672007475

碩士 === 輔仁大學 === 物理學系 === 91 === The high-temperature α-phase of FeSi2 is metallic while low-temperature β-phase is a semiconductor . In this thesis we present the study of thermopower S, thermal conductivityκand electrical conductivityσ of α and β-phases of FeSi2 . Furthermore, the values of Figure of Merit Z = S2σ/κwere calculated and the results shows β- FeSi2 had higher thermpower as well as higher efficiency Z compared with theα- FeSi2. The nanoparticles of β- FeSi2 were fabricated by different methods such as flash evaporation, EDM and ball milling. We discuss how the size effects on S,κandσ inβ- FeSi2. The result show that the values of S, κ and σ in β- FeSi2 nanoparticles were smaller than the bulk. The specific heat of β- FeSi2 nanoparticles was higher than the bulk at 0.3 to 30 K . The magnetic susceptibility of β- FeSi2 nanoparticles and bulks were measured from 2 to 300 K, and the results reveals thatβ- FeSi2 nanoparticles have superparamagnetism and Blocking Temperature at 70 K.