Ionic conductivity and structural phase transformations for hexagonal and cubic Bi_1.33U_0.33La_0.33O_3.5 polymorphs

摘要

The hexagonal and cubic Bi_1.33U_0.33La_0.33O_3.5 polymorphs by heating at 950 deg C a mixture of Bi_2O_3 and LaUO_4+x. When the reaction mixture is slowly cooled to room temperature, the hexagonal phase with cell parameters a_H=4.0285(3) ?, c_H=9.5494- (8) ? is formed. Quenching of the mixture from 950 deg C leads to the formation of the cubic phase with a fluorite-type structure, a_C=5.641(1) ?.