A study of structural non-stoichiometry with respect to oxygen in RBaCo4O7+x single crystals

Abstract

Impurity-free RBaCo₄O_7+x (R = Y, Lu) crystals are grown and the evolution of their structure with varying oxygen concentration in the range 0 ≤ x ≤ 1.3 is studied. The structural features of the studied samples required to develop an extended strategy of the X-ray crystallographic experiment, which made it possible to obtain more accurate data on unit cell parameters and additional information on the features of superstructure modulation and diffuse scattering, along with the phase composition of crystalline samples. A crystal chemical analysis of the known structural models of RBaCo₄O_7+x is performed and suggestions are made about possible structural changes occurring when the oxygen concentration increases up to the limit.