Abstract
The strontium oxide-copper oxide binary phase diagram has been reinvestigated under oxygen pressures of up to 600 bar, in the temperature range 600-850 °C. A new, high-pressure phase, Sr0.74CuO2, has been isolated and characterised. The oxygen stoichiometry, confirmed by thermogravimetry, gives an average formal copper valence of ca. 2.5. X-Ray and electron diffraction analyses suggest that Sr0.74CuO2 has a Vernier structure incommensurate in b. The subcells are body-centred orthorhombic: aI=6.8182(12) Å, bI, = 3.7113(7) Å, cI=11.0203(17) Å, and face-centred orthorhombic: aII=6.8182(12) Å, bII = 2.7290(3) Å, c II = 11.0203(17) Å. The subcells combine into a coincidence (super)cell with b = 92.79(1) Å, which is 25bI and 34b II. The structure of one of the subcells appears to be related to that of Ca0.82CuO2 and NaCuO2. Sr 0.74CuO2 is non-superconducting, at least above 4 K.
Original language | English |
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Pages (from-to) | 1931-1933 |
Number of pages | 3 |
Journal | Journal of Materials Chemistry |
Volume | 5 |
Issue number | 11 |
DOIs | |
Publication status | Published - 1 Dec 1995 |
Keywords
- strontium oxide-copper binary phase diagram
- oxygen pressures
- oxygen stoichiometry
- copper valence
- Vernier structure