Математика, 2005, ¹1 INVESTIGATION OF OXYGEN SUBLATTICE IN HIGH-TC CRYSTALS BY CHANNELING TECHNIQUE A. S. Borovik, V. S. Malyshevsky, S. V. Rahimov channeling technique. <...> The angular dependence of resonant nuclear reaction yield of ions He+ Institute of Physics, Rostov State University, Rostov-on-Don The features of the oxygen sublattice in a crystal YBa2 Cu3 O7 are investigated by from oxygen nucleuses at energy of ions 3.055 MeV channeled along <001> direction is measured. <...> The best agreement of the calculated angular dependence of the reaction yield with experimental data are achieved at the assumption, that the oxygen sublattice are partly disordered (about 20 % of the oxygen atoms are random situated in the plane (110)) and the atoms of oxygen in oxygen chains are displaced from crystal sites at distance ~ 0.3 C in the plane (110). <...> INTRODUCTION The channeling effect of the charged particles for research of crystals of complex chemical structure allows receiving the unique information on distribution of impurity, radiating defects and displacement of atoms from crystal sites in a crystal lattice [1]. <...> For example, the research of the crystal YBa2 [2] has shows the abnormal change of static (and/ or dynamic) displacement of atoms from crystal sites near the temperature of transition to the high-Tc Cu3 O7 state. <...> The shoulder method of the Rutherford backscattering angular dependences has enabled defining the model of structure YBa2 oxygen atoms [3]. <...> Developed earlier in [4] the approach to Cu3 O7 the description the channeling effect of ions in multicomponent crystals allows calculating the basic channeling parameters for the crystal structure under the given experimental conditions. <...> It has allowed by comparison of the calculated and experimental results for various crystallographic directions to receive the detailed information in [58] on structural features of a crystal lattice of La2 Nd2CuO4 in a small depth (up to 0.1 mkm). <...> In © Borovik A. S., Malyshevsky V. S., Rahimov S. V., CuO4 2005. 128 and , containing static displacement of by the channeling method in the present work the research of features of channeling effect of He+ YBa2Cu3 theoretical analysis of experimental data on the angular dependence of resonant elastic scattering yield He+ O7 from oxygen nucleuses the new data on structural features oxygen sublattice are obtained. <...> THEORETICAL TREATMENT The ion distribution, flux-peaking <...>