Percolation Behaviour in the Magnetic Permeability and Electrical Conductivity in Conducting Magnetic - Insulating Non Magnetic Binary Composites

McLachlan, David S ; Doyle, T B ; Sauti, Godfrey [Point of Contact]

关键词: PERCOLATION;    MAGNETIC PERMEABILITY;    CONDUCTIVITY;    ELECTRICAL RESISTIVITY;    CONCENTRATION (COMPOSITION);    GADOLINIUM-GALLIUM GARNET;    POLYTETRAFLUOROETHYLENE;    TEFLON (TRADEMARK);    TALC;   

RP-ID  :  NF1676L-28419

学科分类：物理（综合）

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

Experimental results of the complex magnetic permeability (µ) and the electrical conductivity (σ) of a granular paramagnetic Gadolinium Gallium Garnet (GGG: 0.3–26 vol%) and Teflon (PTFE) system are presented and discussed in relation to previously published (conductivity) and unpublished (permeability) studies on granular Fe3O4 – talc and Ni – talc wax systems. In these systems plots of the real conductivity (σ'(sub m)) against the volume fraction (φ) lie on characteristic sigmoid curves that when fitted to the Two Exponent Phenomenological Percolation Equation (TEPPE) confirm the existence of “percolation microstructures” with critical volume fractions (φ(sub c)). The plots of the real and imaginary permeability (µ'(sub m)) and (µ"(sub m)) satisfactorily fit to the TEPPE using the φ(sub c) obtained in each case from the “conductivity” measurements. In all three cases the conductivity results gave the exponent t > 2, and the permeability results gave t < 1.