The formation of the solid solution Bi-2(Sr2-xCax)CuOy with the 2201 s
tructure has been demonstrated by comparing its lattice parameters wit
h those in Bi2+xSr2-xCuOy and Bi-2(Sr2-xMgx)CuOy systems. The solid-so
lution range of Bi-2(Sr2-xCax)CuOy has been found to be 0 less than or
equal to x less than or equal to 0.15 under the present experimental
conditions.