CARNOTITE ANALOGS - SYNTHESIS, STRUCTURE AND PROPERTIES OF THE NA1-XKXUO2VO4 SOLID-SOLUTION (0 LESS-THAN-OR-EQUAL-TO X LESS-THAN-OR-EQUAL-TO 1)

Crystal structures of synthetic K2(UO2)2V2O8 (carnotite) and Na2(UO2)2V2O8 have been refined using single-crystal X-ray diffraction. The alkali-metal ions were shown to lie between [(UO2)2V2O8]infinity layers. A continuous solid solution was obtained between these two compounds. Both compounds and the solid solution have high ionic conductivity. For example, K and Na compounds have conductivities at 500-degrees-C of 9.2 x 10(-5) and 1.7 x 10(-4) S cm-1, respectively, and activation energies of 0.57 and 0.52 eV.