m PHYSICA © ELSEVIER Physica C 282-287 (1997) 1033-1034 Study on the phonon spectroscopy and transport properties Peixun Luo, Ding Jin, Cunyi Xu, Jian Zuo, Keliang Hu, Xiao-Guang Li and Yuheng Zhang Structure Research Laboratory, University of Science and Technology of China Hefei 230026, P. R. China The phonon vibration modes and transport properties of a series of samples YI,xNd,.Sr2Cu27Mo0307-<'> (x= 0, 0.1, 0.2, 0.5, 0.8, 1.0 ) have been studied. It WIlS found that the Sr-based 123 cuprates have different structure characteristics compared to Ba-based 123 phase, and the depression of superconductivity as x increases was interpreted as the result of expansion and distortion of crystal lattice as well as the charge redistribution between the Cu-O plane and the carrier reservoir. All the compounds RSr2Cu2.7Moo.307 ( R= rare earth element except Ce, Lu ) have superconducting transition temperature To == 30K, excluding R= La, Pr, and Nd [1], which is very different to where both and have Tc as high as others ( == 90K ). We intended to fmd the intrinsic difference between the Sr-based 123 type and Ba-based 123 type cuprates. The samples YI_xNd,.Sr2Cu27Mo0307-<'> (x = 0, 0.1, 0.2, 0.5, 0.8, 1.0) were prepared by solid state reaction technique. The Raman and Infrared spectra were show in Fig. I. All the main Raman peaks are the typical vibration modes in 123 phase cuprates. The out-of-phase viQration bending mode of Cu(2)- 0(2,3)-Cu(3) around 320 cm,l shifts to lower frequency, while the out-of-phase vibration stretching mode of apical 0(4)-Cu(I)-(4) around 520 cm,l shifts to higher frequency when x increases. In the Infrared spectra, with increasing Nd content, the in-phase 0(4)-Cu(1)-0(4) stretching vibration mode A 2u around 650 cm- I shifts to higher frequency, behaving like the out-of-phase vibration mode at 520 cm,l in Raman spectra. The frequency 0) is much higher than the corresponding mode's frequency in , which is 579 cm'I, although the average ion size of (Y 01 Pr 09 ) nearly equal to that of Nd. It suggests that the bonding length of 0(4)-Cu(l) in RSr2Cu27Moo.307-<i is some shorter than that in Since the lattice parameters a (b), c is smaller than that of the latter, it can be regarded that in the Sr-based 123 type cuprates ° atoms prefer to occupy the 0(1 *) sites (in the middle offour Cu(1) atoms) instead of 0(1) sites 0921-4534/97/$17.00 © Elsevier Science B.Y. All rights reserved. PH S0921-4534(97)00601-1 to form Cu-O chains. As the bonding length of Cu(1)-O(1 *) is longer than Cu(1)-O(I) in 0(4) is allowed to be nearer to Cu(I), and the frequency of A2 u is higher as a result. The ° atom in 0(1 *) site has a coordination number of 6 100 200 300 400 500 600 700 Ram an Shift (em ,I) Figure 1. The Raman (a) and Infrared (b) spectra of Y l,xNd,.Sr2Cu27Moo.307-<'>