Ionic charges in high-Tc yttrium-barium ceramics and oxygen content

Teoretical study is made on distribution of valent charge in YBa2Cu3O6+x ceramics. The calculation method is based on pseudopotential division into large but smooth and small but rapidly oscillating components. Nonstoichiometry for intermediate x is treated according to the method of virtual potential. Charts of electron density in different crystallographic planes are presented. Dependences of charges within the limits of atomic spheres on their radii are given for the series of oxygen index values. The obtained results enable answering some questions about valent states of ions. For example: effective oxygen charge is close to -1, copper -to +1.6 and it changes depending on x or ion position in lattice cell much weaker than the character of charge distribution