A Study on the High-Pressure Synthesis and Properties of Praseodymium-Substituted R2Ba4Cu7O14+δ (R = Nd, Eu, Tm) Cuprates

Feng-Shih Kao ； Teng-Ming Chen

《Chinese Journal of Physics》 34卷2S期 (1996/04) Pp. 561-565

並列摘要

The formation of phases in the (R1-xPrx)2Ba4Cu7O14+δ (R = Nd, Eu, Tm; Pr-doped R247 phases) system with x = 0 - 0.5 was investigated. Samples of the above three series were synthesized at 980℃ at 25 bar O2, followed by annealing at 300℃ under 130 bar O2 for 30 hours. Oxygen content of the samples has been determined by iodometric titration. X-ray diffraction indicated that nearly single-phased samples were obtained with x ＜ 0.4, 0.5 and 0.5 for R = Nd, Eu and Tm, respectively, and the cell dimension of the Pr-doped R247 phases was found to expand steadily with increasing Pr content. Field-cooled temperature-dependent magnetization measurements showed that Tc of the Pr-doped R247 decreased with increasing Pr content. We have compared the dTc/dx for the three series with R = Nd, Eu and Tm with that for R = Y as a function of size of R^3+ ions and the results are discussed. In addition, the field-dependent magnetization studies at 5 K for a series of (Eu1-xPrx)2Ba4Cu7O14+δ samples with x = 0, 0.2, and 0.4 are also reported.