CRYSTAL SYNTHESIS OF FLUORITE-TYPE SOLID SOLUTIONS IN THE SYSTEM PbF//2-BIO//XF//3// minus //2//x(x approximately equals 0. 5) BY HYDROTHERMAL REACTIONS.

Two fluorite-type solid solutions of Pb//1// minus //yBi//yF//2//30 //y(y approximately less than 0. 5) and Pb//1// minus //yBi//yO//0//. //5//yF//2(y greater than 0. 8) were synthesized hydrothermally from alpha -PbF//2 and beta -BiF//3 at 250 degree to 500 degree C for 4 h to 14 days under 100 MPa using sealed Pt-capsules. The water molecules and/or hydroxyl ion (OH** minus ) in the products synthesized hydrothermally were not detected by Fourier transform infrared spectrophotometry. Pb//1// minus //yBi//yF//2// plus //y solid solution ( beta -PbF//2ss) was synthesized at 400 degree C from compositions containing 0 to 50 mol% BiF//3.