【摘要】 用交流磁化率装置测量了Ba-Y-Cu-O系统的抗磁屏蔽效应,发现在同一样品中存在两个超导相,两个相的体积比例和X-射线衍射峰的高度相对应。另外用蓝宝石做样品支架,背底讯号比用紫铜做支架小100倍,基本上可忽略背底的影响。更多还原

【Abstract】 We have measured a.c. susceptibility of several samples in Ba-Y-Cu-O system and found two superconductive phases in the same sample (Fig. 1). The higher Tc superconductive phase increases and the lower Tc superconductive phase decreases when the yttrium content is decreased. The lower Tc phase is disappeared when Ba:Y ratios are larger than 1.6:1.4. The X-ray powder diffraction patterns for four samples are shown in Fig. 2 and indicated the same results as the above. In addition, the temperature dependence of the backing signals for the copper holder and the sapphire holder are shown in Fig. 3 and obtained the much smaller backing signal for sapphire holder.更多还原