Electrical Properties of Gadolinium-Europium Zirconate Ceramics

摘要

(Gd_(1-x)Eu_x)_2Zr_2O_7 (0≤x≤1.0) ceramics are prepared via a solid-state reaction process at 1973 K for 10 h in air. (Gd_(1-x)Eu_x)_2Zr_2O_7 (0.2≤x≤1.0) ceramics exhibit an ordered pyrochlore-type structure; however, Gd_2Zr_2O_7 has a disordered defect fluorite-type structure. Raman spectroscopy analysis indicates that the degree of structural ordering increases with the increase of Eu content. The electrical properties of (Gd_(1-x)Eu_x)_2Zr_2O_7 ceramics are investigated using complex impedance spectroscopy over a frequency range of 0.1 Hz to 20 MHz from 623 to 923 K. Electrical conductivity obeys the Ar-rhenius equation. Both the activation energy and the preexpo-nential factor for grain conductivity decrease with increasing europium content from Gd_2Zr_2O_7 (x = 0) to Eu_2Zr_2O_7 (x = 1.0). The measured electrical conductivity of (Gd_(1-x)Eu_x)_2Zr_2O_7 ceramics increases with increasing Eu content and temperature. Electrical conductivity of the pyrochlore-type materials is higher than that of the defect fluorite-type material in (Gd_(1-x)Eu_x)_2Zr_2O_7 solid solution systems. The electrical conductivity of (Gd_(0.4)Eu_(0.6))_2Zr_2O_7 is almost independent of oxygen partial pressure from 1.0 × 10~(-4) to 1.0 atm. The high ionic transference number of (Gd_(0.4)Eu_(0.6))_2Zr_2O_7 ceramic at different temperatures proves that conduction is purely ionic with negligible electronic contribution.