Electronic structure of a hole doped oxide with a quasi-1D crystal structure Y2-x(Sr,Ca)(x)BaNiO5

The effect of hole doping into the divalent nickel oxide Y2BaNiO5, which pr ovides a good example of one-dimensional electronic structure in the presen ce of strong d-d interactions, has been examined by means of several techni ques including X-ray absorption and electron energy loss spectroscopies at oxygen K-edges (O K-edges). The crystal structure of this compound shows on e-dimensional chains of vertex-sharing NiO6 octahedra running along the z-a xis. Hole doping into this material is realized by substituting Ca2+ or Sr2 + ions for the Y3+ ions. We suggest that the doped holes have antibonding N i 3d(3z(2)-r(2))-O2p(z) character. (C) 2001 Elsevier Science B.V. All right s reserved.