| 摘要 |
PURPOSE:To increase the superconductive transition starting temperature by burning a mixture containing Tl, Bi, Sr, Ca, Cu and O and, as necessary, Pb at specific atomic ratios of Tl, Pb, Bi, Sr, Ca and Cu, then annealing the burned mixture. CONSTITUTION:Raw materials such as Tl2O3, PbO, Bi2O3, SrCO3, CaCO3 and CuO containing Tl, Pb, Bi, Sr, Ca and Cu are weighed so as to provide atomic ratios of (x):(y):(z):2:(2+p):(3+q) (x+y+z=1; 0.3<=x<=0.95; 0<=y<=0.5; 0.05<=z<=0.4; 0<p<=1.5; 0<q<=1. 5) and the powders other than the Tl2O3 are mixed. The mixed powder is formed, then calcined at 750-900 deg.C and subsequently pulverized. The Tl2O3 is then added so as to afford the atomic ratio (x) of Tl. The resultant powder mixture is mixed and burned at 850-1000 deg.C in al O2 atmosphere. The resultant burned substance is subsequently annealed at 300-900 deg.C to provide a superconducting material having a crystal phase composed of oxides expressed by the formula (r is about 9) and 100-125K superconductive transition starting temperature. |
