BaCuO_(2.5)的电子能谱和不同温度下合成的Eu(Y)-Ba-Cu-O化合物的性质和铜原子价态

CuZp XPS SPECTRUM OF BaCuO_(2.5) AND THE PROPERTIES AND COPPER VALENCE OF E(uY)-Ba-Cu-O COMPOUNDS PREPARED UNDER DIFFERENT TEMPERATURE

XPS测试表明,在氧气中合成的BaCuO_(2.5)的Cu2p_(3/2)电子结合能比CuO的高约1.1eV。XRD分析表明,BaCuO_(2.5)在高温(920℃)下加热后分解成BaCuO_2。由此推测高温超导体中难以存在Cu^(3+)。在低温(580℃)下用BaO_2、Cu(NO_3)_2·3H_2O和Eu_2O_3(或Y_2O_3)为原料合成的化合物中含Cu^(3+)/Cu^(2+)混合价态,但室温下它们是半导体,在液氮温区无超导性。

XPS determination shows that the Cu2p3/2 binding energy of BaCuO2.5 prepared in O2 is 1.1eV higher than that of CuO.XRD analysis indicates that BaCuO2.5 decomposes into BaCuOj after heating at 920℃. It is inferred that Cus+ is not present in the high-Tc superconductors. Whereas the Cu3+/Cu2+ mixed valence is present in Eu (Y) -Ba-Cu-O compounds prepared at 580℃, but these compounds do not show any superconductivity in liquid nitrogen and exhibit semiconducting behavor at room temperature.