PHASE-DIAGRAM AND PHASE-SEPARATION IN LA2-XSRXCUO4+DELTA

The phase diagram of the title system is remarkably rich, exhibiting r egions of long-range antiferromagnetic order, short-range (spin-glass- like) order, high temperature superconductivity, or none of these. Her e, the phase diagram is reviewed, with an emphasis on our recent studi es using La-139 NQR, powder and single crystal neutron diffraction, an d magnetization measurements for 0 less-than-or-equal-to x less-than-o r-equal-to 0.15 and 0 less-than-or-equal-to delta less than or similar 0.1.