TEMPERATURE-DEPENDENCE OF PHONON RAMAN-SCATTERING IN Y2BA4CU7O15-DELTA

The temperature dependence of A(g) symmetry phonons in a Y2Ba4Cu7O15-d elta (delta almost-equal-to 0.18, T(c)=93 K) superconductor have been investigated between 10 and 300 K by means of Raman scattering. The ob served changes in frequency and line-width between T(c) and 10 K for t he CuO2- and BaO-plane oxygen modes are consistent with the opening of a superconducting pp, 2DELTA, between 340 and 430 cm-1. The magnitude s of these phonon anomalies are similar to what has been reported for the respective modes in YBa2Cu3O7-delta (delta=0.19). The behaviours o f the Ba mode and the chain-oxygen mode below T(c), i.e. softening and hardening respectively, are approximately the same as those we observ e in a YBa2Cu4O8 (T(c)=82K) sample. Evidence of phonon frequency anoma lies at temperatures above T(c) is discussed in relation to difference s in doping-level between YBa2Cu4O8 and Y2Ba4Cu7O15-delta.