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INFRARED REFLECTIVITY IN OXYGEN-CHAIN-EQUALIZED AND ORDER STABILIZED PAIRS OF 123 COPPER OXIDES // Tomsk State Pedagogical University Bulletin. 2002. Issue 2 (30). P. 3-10

The results of the infrared reflectivity measurements comparatively performed on the oxygen-chain-equal¬ized polycrystalline pair-samples of YBa2Cu30B4,x, are reported. The samples were prepared from the full/ empty oxygen-chain [Cu,OJ^/[Cu,0stoichiome-try end terms which where for a long time equilibrated under vacuum at a low temperature and were order-stabilized in the appropriate temperature-composition domain of existence of Oil and OIII superstructures. The single crystal IR-active phonon modes were ex¬tracted from the reflectivity data for the ceramic sam¬ples in the generalized effective medium approxima¬tion for the frequency-dependent dielectric permittivi¬ty. Then the fitted values of c-oriented IR-active pho¬non frequencies were interpreted within the framework of a lattice-dynamics transferable shell-model. The evidences of a phonon reconstruction related to the existence of the high-ordered oxygen-vacancy order¬ing superstructures OII and OIII in the oxygen-chain-equalized polycrystalline pair-samples of YBa2Cu306 are given.