Crystal structure of La{sub 3}Nb{sub 0.5}Ga{sub 5.5}O{sub 14} at 20 K

The atomic structure of La{sub 3}Nb{sub 0.5}Ga{sub 5.5}O{sub 14} single crystals (space group P321, R = 2.21%, R{sub w} = 2.31%) at 20 K was determined using X-ray diffraction. A comparative analysis of the structural characteristics determined at temperatures of 293 and 20 K did not reveal a noticeable redistribution of bond valences that could be considered precursors of a possible phase transition accompanied by the reduction of the symmetry of the crystal. The assumption was made that the anomalous behavior of the permittivity e{sub 33} of the La{sub 3}Nb{sub 0.5}Ga{sub 5.5}O{sub 14} single crystals is associated with the decrease in the possible relative displacements of the Ga(1) and Nb atoms occupying the cation position with point symmetry 32 in a 1: 1 ratio.