NEUTRON-DIFFRACTION AND NEUTRON SPECTROSCOPIC STUDIES OF CRYSTALLINE ELECTRIC-FIELD IN ALSR(2)LNCU(2)O(7) (LN = Y, ER, HO)

Investigation of the substitution effects for various sites in the per ovskite-like systems with a general formula M-1-(Sr, Ba)-Ln-(Cu, M-2)- O (M = Bi, T1, Hg, Al, Ga, Zn, Ni and Ln = rare earth) is of great int erest in connection with the problem of high-T-c superconductivity. Th e 1212 AlSr(2)LnCu(2)O(7) (Ln = rare earth) compounds, non-superconduc ting insulating structural analog of the 123 LnBa(2)Cu(3)O(x) supercon ductors, exhibit unusual magnetic properties resulting from an interac tion between Cu magnetic moments within the CuO2 planes and the rare-e arth subsystem. To obtain precise information on the crystal structure neutron powder diffraction measurements have been performed for the 1 212 AlSr(2)LnCu(2)O(7-x) (Ln = Y, Er, Ho) compounds. Inelastic neutron scattering has been employed to search for the crystalline-electric-f ield !CEF) transitions in these compounds. The observed CEF spectra ar e discussed in terms of the structural model which involves locally in homogeneous oxygen distribution in the basis planes. (C) 1998 Elsevier Science B.V. All rights reserved.