Study of Sintering Behaviour and Electrical Conductivity of Cr-Zn-Fe-O System

摘要

A series of chemical compositions based on Cr, Fe and O with Zn as a partially substitutingion has been prepared in the general formula ZnxCr1-xFe2O by coprecipitation method usingNH4OH as the precipitating agent at pH=10.3. The prepared samples were identified by boththermal analysis (DTA and TGA) and X-ray diffraction (XRD). It was found that no singlephase was obtained for any of the studied compositions but a mixture of different phases wasobserved, depending on the molar percentage of zinc ion substitution as well as on the sinteringtemperature. The temperature dependence of the electrical conductivity, σ, of the preparedsamples was plotted between 25 and 680℃. It was observed that the electrical conductivityincreased with temperature for both samples with x=0.00 and 0.80 Zn ion content whiIe itwas nearly temperature independent for samples with intermediate Zn concentration x=0.2 and0.5 mol fraction. The activation energy, Ea, calculated from the linear reIation, lgσ-1000/T forthe final mixtures (sintered at 1300℃) was calculated.