Structural and Electrical Properties of T′-type Ln2CuO4 (Ln = Pr, Nd, Sm, Eu and Gd) ceramics

T'-type Ln(2)CuO(4) (Ln = Pr, Nd, Sm, Eu and Gd) were successfully synthesized in phase pure form using conventional solid state reaction and sintering route. For all the Ln(2)CuO(4) samples, the solid state reaction temperature was found to be 950 degrees C and pure phase was realized only after 2-3 intermediate milling and solid state reaction cycles, irrespective of the lanthanide ion radius. Effect of lanthanide ion contraction on the structural properties was clearly revealed by the powder X-ray diffraction, with the XRD peaks observed to be shifting towards higher 2 theta values with the decrease in Ln ionic radii. The optimum sintering temperature of these solid state reacted Ln(2)CuO(4) powder was found to be 1100 degrees C except for Pr2CuO4 powder. The conductivity of these samples were tested over a wide temperature range (-100 to 150 degrees C), an anomaly was observed in the conductivity of all the Ln(2)CuO(4) samples near the antiferromagnetic ordering temperature of Cu (similar to 30 degrees C), thus suggesting the bearing of ordering of magnetic moments on the electrical properties.