SYNTHESIS, STRUCTURE, AND MAGNETISM OF T'-PHASE LA2-XYXCUO4 - PROPERTIES OF THE 214 T'-PHASE WITHOUT MAGNETIC RARE-EARTH ELEMENTS

We report the synthesis, structure, and magnetic properties of magneti c-rare-earth-free T'-phase material La2-xYxCuO4. Synthesis of this met astable compound was attempted by three different techniques: 1) a sol ution-based technique, starting from either oxides or nitrates, follow ed by low-temperature (less than or equal to 600 degrees C) reaction; 2) high-pressure, high-temperature synthesis (25 kbar, similar to 1000 degrees C); and 3) low-temperature synthesis (similar to 400 degrees C) in a KOH flux. The first technique yields single-phased T'-phase La 2-xYxCuO4 materials over the range 0.10 less than or equal to x less t han or equal to 0.80 high-pressure synthesis has been successful near x = 2, but not for lower values of x. La2-xYxCuO4 is a minority phase product of the the flux technique. The solution-based technique yields smaller particle sizes than the flux technique. Magnetic measurements indeed reveal the behavior of the Cu magnetism, although the low temp erature data for the solution-based samples are dominated by similar t o 8% Cu2+ defects, more than typically encountered in other magnetic-r are-earth-free copper oxides. We observe a static susceptibility (corr ected for core diamagnetism) of chi(o) = 1.3x10(-4) cm(3)/mole. Attemp ts to dope these materials with Ce-have not yet been successful.