Sr_0.09Ca_0.91CuO₂の合成と結晶構造

抄録

Sr_0.09Ca_0.91CuO₂ was obtained by heating a powder mixture of SrCO₃, CaCO₃, and CuO at 1000°C in flowing oxygen. The compound has a tetragonal symmetry, P4/mmm, and is characterized by a=3.8581 (1), c=3.1997 (1)Å, Z=1, D_m=4.86g/cm³, and D_cal=4.88g/cm³. The crystal structure was determined and refined to R_p=3.7% by the Rietveld analysis of X-ray powder diffraction data. The compound has an oxygen-deficient perovskite structure. A copper atom is in a square plane of oxygen atoms. This square plane forms a Cu-O flat sheet sharing the oxygen atoms at vertices of the square. The bond length of Cu-O is 1.929Å. Sr(0.09) and Ca(0.91) atoms are statistically in an oxygen square prism. The interatomic distance of (Ca, Sr)-O is 2.506Å. This compound is a p-type semiconductor with electric conductivity of 1.2×10^-4(Ω·cm)^-1 at 22°C.