Properties of the Ln2BaCuO5 (Ln = Nd, Sm, Dy, Ho, Tm, Yb) cuprates

The thermal expansion and electrical conductivity of Ln(2)BaCuO(5) (Ln = Nd, Sm, Dy, Ho, Tm, Yb) were measured in air at temperatures from 293 to 1073 K. All of the materials were found to exhibit semiconducting behavior. As the ionic radius of Ln(3+) decreases, the: conductivity of Ln(2)BaCuO(5) drops, and the activation energy of conductivity rises-from 26.4 kJ/mol for Ln = Nd to 66.4 kJ/mol for Ln = Yb. Over the entire temperature range examined, the linear thermal expansion coefficient of all the Ln(2)BaCuO(5) compounds studied is independent of the nature of the rare-earth ion and falls in the range (11-13) x 10(-6) K-1.