Metal-insulator transition and magnetic properties of La1-xEuxNiO3 (0 <= x<= 1)

This paper reports S-ray diffraction patterns, Rietveld fit profiles, elect rical resistivity de magnetic susceptibility, and electron paramagnetic res onance (EPR) measurements of La1-xEuxNiO3 (0 less than or equal to x less t han or equal to 1), A shift to high temperature of the metal-insulator tran sition temperature with x and hysteresis in the electrical resistivity and magnetization versus temperature at intermediate concentration of the compo und are observed, The antiferromagnetic order of the hii sublattice can be observed after subtracting the magnetic contribution of the rare earth ions . A change in space group from R-3c to Pbnm for x greater than or equal to 0.4 was detected, as was the appearance of magnetic order. Samples with 1% Gd3+ probe mere studied by EPR, Drastic changes were observed in the shape of the lines with x, though the crystal field symmetry of the Gd sites rema ined constant in all the samples studied. We observed that when Eu substitu tion increases, the number of Gd ions that contribute to the crystal-field spectrum diminishes. A possible cause of this effect is a previously report ed increase in the Ni-O covalence in the neighborhood of the Eu sites. (C) 2000 Academic Press.