  We present the model of superconducting ceramics using the single band
extended Hubbard Hamiltonian. We investigate the simultaneous presence of
antiferromagnetism (AF) and d-wave superconductivity (SC) in the coherent
potential (CP) approximation applied to the on-site Coulomb repulsion $U$. We
consider the hopping interaction, $\Delta t$, the inter-site charge-charge
interaction, $V$, (creating SC), and the single site Hund's type exchange
interaction, $F_{in}$, (creating AF). The influence of these interactions on
the separation of superconducting and antiferromagnetic phases near the
half-filling point is investigated. Results are compared with the experimental
data for YBaCuO and NdCeCuO compounds.
