STRUCTURAL AND ELECTRONIC-PROPERTIES OF THE COMPOUNDS BA(4)IR(3)MO(12) (M=LI, NA, MG, Y, LU, ZR AND CE)

Polycrystalline samples of the Ir-IV/Ir-V compounds Ba(4)Ir(3)MO(12) ( M = Li, Na, Mg, Y, Lu, Zr and Ce) have been prepared using standard ce ramic techniques. The products have been characterized by X-ray powder diffraction, SQUID magnetometry (6 < T/K < 296) and electrical conduc tivity measurements 80 < T/K < 296). They all adopt the 6H perovskite structure with the cation M occupying only the vertex-sharing six-coor dinate sites and with iridium occupying the face-sharing sites and the remaining 25% of the vertex-sharing sites. These compounds are non-me tallic and have low magnetic susceptibilities with only a relatively s mall temperature dependence, suggesting that extensive spin-pairing oc curs throughout the measured temperature range.