The ordering degree and thermal conductivity in the pyrochlore-type composition systems with a constant cation radius ratio

Abstract

A2B2O6O'-type pyrochlore compounds with a constant average cation radius ratio (r(A3+)/r(B4+)=1.5), (Gd1−xLnx)2(Zr1−yTiy)2O6O' (Ln: Nd, La), were synthesized by solid state reaction at 1600°C for 10h. The ordering degree and thermal conductivity of the ceramics were investigated. XRD and Raman results revealed that all the ceramics exhibited pyrochlore phase but different ordering degree. Compared with B-site substitution in Gd2Zr2O7, A-site substitution led to higher ordering degree and lower thermal conductivity when the value of r(A3+)/r(B4+) kept at a constant. The lowest thermal conductivity could be obtained by both A-site and B-site substitutions.