Evidence of Sr-Deficiency in Bi2Sr2-αCa1Cu2O8 and Preparation of Stoichiometric Semiconducting Bi2Sr2Ca1Cu2O8

Abstract
When samples with the starting composition of Bi:Sr:Ca:Cu=2:2:1:2 were heat-treated under the oxygen partial pressure range from 1 to 0.0001 atm at 820°C, at least three different multiphase regions with the following component phases appeared: Bi2Sr2Cu1O y +Sr-rich Bi-Sr-Ca-Cu-O+Sr-deficient Bi2Sr2-αCa1Cu2O x , stoichiometric Bi2Sr2Ca1Cu2O8, and Bi2Sr2Ca1O6+Cu2O. The amount of Sr-deficiency in the Bi2Sr2-αCa1Cu2O8 homogenized sample with the stoichiometric composition of Bi2Sr2Ca1Cu2O8 exhibited semiconductivity.