Flux Growth of [NaK6F][(UO2)3(Si2O7)2] and [KK6Cl][(UO2)3(Si2O7)2]: The Effect of Surface Area to Volume Ratios on Reaction Products
journal contribution
posted on 2016-02-02, 00:00 authored by Gregory Morrison, Hans-Conrad zur
LoyeSingle crystals of
two new salt-inclusion uranium(VI) silicates,
[NaK6F][(UO2)3(Si2O7)2] and [KK6Cl][(UO2)3(Si2O7)2], were grown from
mixed alkali halide salt fluxes. Both compounds crystallize in the
[NaRb6F][(UO2)3(Si2O7)2] structure type in the orthorhombic space group Pnnm with lattice parameters a = 11.0819(5)
Å, b = 13.1149(6) Å, and c = 7.8418(4) Å ([NaK6F]) and a =
11.0830(7) Å, b = 13.5850(4) Å, and c = 7.8693(5) Å ([KK6Cl]). The surface area
to volume (sa/vol) ratio of the reaction, controlled by the reaction
vessel dimensions, has a strong influence on the reaction products
with small sa/vol ratios favoring the growth of the salt-inclusion
phases. Both compounds exhibit the typical luminescence of the uranyl
group with the luminescence of [KK6Cl][(UO2)3(Si2O7)2] being less intense
than [NaK6F][(UO2)3(Si2O7)2], likely due to quenching by the Cl– ions.
