LOW-TEMPERATURE SYNTHESIS OF BINARY CUPRATES FROM HYDROXIDE PRECURSOR

Binary cuprates of Sr2CuO3+delta and SrCuO2 have been synthesized at l ow temperatures below 500 degrees C under various values of partial ox ygen-pressure P-O2 by thermal decomposition of hydroxide precursors, S r2Cu(OH)(6) and SrCu(OH)(4), respectively. The tetragonal Sr2CuO3+delt a (delta similar to 0.3) is Obtained by the heat-treatment at 400 degr ees C and P-O2 greater than or equal to 0.2 atm. The value of 6 appear s to be independent of P-O2 and unchangeable. On the other hand the or thorhombic Sr2CuO3+delta (delta similar to 0) is obtained by the heat- treatment at 400 degrees C in flowing gas of N-2. For 0 < P-O2 < 0.2 a tm, a mixture of the tetragonal and orthorhombic phases is obtained. T he orthorhombic SrCuO2 is obtained by the heat-treatment at 500 degree s C in flowing gas of N-2, although the tetragonal SrCuO2, namely, the so-called infinite-layer compound is not obtained.