Influence of oxygen stoichiometry on the electronic properties of La4Ni3O10 +/-delta

Some different oxygen content La4Ni3O10+delta (delta=0.02,0.12,-0.22) compo unds were prepared in order to study the influence of Ni3+ content on the e lectronic properties. A metal-metal transition was detected at 140 K for th e as-prepared (La4Ni3O10.02) and reduced (La4Ni3O9.78) compounds. From the electrical conductivity, Seebeck coefficient and magnetic studies of the di fferent samples, oxygen stoichiometry was found to be a critical parameter in defining the existence of a less conductive low temperature state. The r esults are interpreted assuming the existence of charge order in the nickel oxide planes of the layered perovskite-type structure. (C) 2000 American I nstitute of Physics. [S0021-8979(00)05613-9].