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Spin gap effect on bulk system of Eu/sub 1+x/Ba/sub 2-x/Cu/sub
3/ O/sub delta/(x=0~0.4) were achieved by, rather than adjusting
the oxygen deficiency,alternatively substituting Eu/sub 3+/ for
Ba/sub 2+/ to control hole number.But thesamples were determined
to be of impure phases, and the underdoping states under
investigation were assumed to be of saturated oxygen
concentration. In this study pure phase samples was first
obtained through adjusting the molar number of Cu in the
preparation process, where X-raypower diffraction analysis and
EDAX were used to monitor the status of thesample. The relations
between annealing time and oxygen concentration for samples of
various underdoping state was found by weight measuring method,
where the annealing time decreases from twenty -five days to
three days as the doping concentration increases. However that
spin gap temperature for most samples were determined to be
above 230K was not predicted by RVB theory. This discrepancy was
due possibly to the inhomogeneity of the bulk samplerevealed by
magnetic measurements.
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