Oxygen ionic conductivity of NTE materials of cubic Zr1−xLnxW2−yMoyO8−x/2 (Ln = Er, Yb)

Cubic Zr1−xLnxW2−yMoyO8−x/2 (Ln = Er: x = 0.01, 0.02, 0.03; y = 0; Ln = Yb: x = 0.02, 0.03; y = 0.4) solid solutions, well-known negative thermal expansion (NTE) materials were prepared by using conventional solid state reactions. The morphology and the composition of the fracture surfaces of the ceramic pellets were determined by SEM and EDX technology. The conductance properties of the pellets, such as conductivity and conductance activation energy, were studied by AC impedance spectroscopy and the materials perform clearly oxygen ionic conduction with the conductivity of about 10−4 S cm−1 at 673 K, a comparable value to that of ceria based solid electrolytes. The substitution of Mo for W enhanced the thermal stability of ZrW2O8, so that the conductivity of Zr0.98Yb0.02W1.6Mo0.4O7.99 ceramic can be measured up to 873 K, which is about 5.9 × 10−4 S cm−1.

The temperature dependence of grain conductivities σb1's of Zr1−xErxW2O8−x/2 and Zr0.98Yb0.02W1.6Mo0.4O7.99 ceramic pellets. The data demonstrate clearly that oxygen ionic conductivities are about 10−4 S cm−1 at 673 K, which is comparable to that of ceria based solid electrolytes. The Mo substitution in ZrW2O8 enhances the thermal stability, so that the conductivity of Zr0.98Yb0.02W1.6Mo0.4O7.99 ceramic was measured up to 873 K which is about 5.9 × 10−4 S cm−1.Figure optionsDownload as PowerPoint slide