Powder diffraction studv of LiCu_2O_2 crystals

摘要

LiCu_2O_2 crystals grown by spontaneous crystallization from the fluxed melt were studied by powder X-ray diffraction. The phase analysis shows that the applied growth conditions are suitable for preparation of a single-phase compound. The as-grown crystals contain only traces of foreign phases (Li_2CuO_2,CuO,Cu_2O) typical for preparation of the LiCu_2O_2 compound. Attempts to anneal or quench the as-grown crystals led to two-phase samples containing LiCu_2O_2 and LiCu_3O_3. X-ray powder diffraction pattern of a LiCu_2O_2 crystal is reported and compared with literature data. The crystal structure is orthorhombic, space group Pnma, in agreement with literature data. Lattice parameters of the studied sample are a = 5.7286(2) A, b = 2.8588(1) A, and c= 12.4143(3) A. Time evolution of a diffraction pattern illustrates a slow increase of the secondary-phases contribution assumed to be due to interaction of the powdered crystal with humid air. A brief summary of compounds known in the Li-Cu-O system is included.