The polarized Raman spectra of Ca2Cu03, C a l . s S r ~. ~C u O ~ and Ca1.6Sro.rCuO3 single oystals and the IR transmission spenra of Ca~Cu03 and Cal.aSro.rOuO~ have been measured. The frequencies of all I'point phonons of Ca2Cuo3 have been dclermined on the basis of assignment of the one-phonon Raman (4) and IR lines 10 definite normal modes and alculalions of the lattice dynamics. The line assignment is wnsislenl wilh earlier mults for Cal.gSr0.2ChO3 as well BS with the line shifts upon substitution of Sr for Ca. I h e inlensive bmad lines in the (bb)polarized Raman speclra of both Sr-free and Sr-subtiluted ?ample (in addition l o the two As Lines already assigned) have been attributed to resonanlly enhanced two-phonon scattering involving modes related 10 motions of Cu andlor O(2) atoms. A coincidence has k e n found between most of the line frequencies and half-widlhs in the (bb)polarized Raman spectra and some of the maxima in the two-phonon density of stales as oblained fmm lattice dynamirs calculations.

No abstract

No abstract