INFINITE-LAYER, T'-PHASE, AND 1-D-LADDER COPPER-OXIDE COMPOUNDS

Results of recent research on electron-doped infinite-layer compounds (e.g., Sr1-xLaxCuO2), T'-phase compounds (e.g., Nd2-xCexCuO4), and spi n-1/2 quasi-1-D ladder compounds (e.g., Sr14Cu24O41) (Ire presented, i ncluding structural and magnetic measurements. Studies of steric effec ts indicate that superconductivity disappears in both electron-doped s ystems for valves of the in-plane lattice constant below a critical va lue, a(cr) approximate to 3.92 Angstrom. Attempts to hole dope both th e infinite-layer and T' phases are described. For the quasi-1-D ladder compound Sr14Cu24O41, the anisotropic susceptibility of this system a nd its ''small gap'' are discussed. Collaborative studies of these sys tems using mu SR, NMR, and other spectroscopies are reviewed.