Effect of Li doping on the critical temperature and glass formation in theBi-Sr-Ca-Cu-O system

A study has been made of the glass-forming ability, structure, and supercon ducting properties of B(i2.)2Sr(1.8)Ca(1.05)Cu(2.15)Li(x)O(y) and Bi2.2Sr1. 8Ca1.05Cu2.15-xLixOy (x=0; 0.3; 0.5; 0.7). The compounds were melted by rf at T = 1300 - 1500 degrees C. Rapid quenching produces glassy alloys whose glass-forming ability is the highest when lithium is substituted for copper . Glass annealing at 700-800 degrees C results in the formation of the HTSC phase 2212 with a critical temperature of up to 91 K. In lithium-doped sam ples the HTSC phase forms at lower temperatures and shorter anneals and it depends on the cooling rate following the anneal. The composition and prope rties of the 2212 phase depend nonmonotonically on the anneal time. The lat tice parameter C of the 2212 phase increases with increasing lithium conten t. (C) 1999 American Institute of Physics. [S1063-7834(99)00401-3].