THE EFFECT OF LITHIUM INTERCALATION ON THE CRYSTAL-STRUCTURE AND MAGNETIC PROPERTY OF LAYERED FEWO4CL

LiFeWO4Cl has been prepared by reductive intercalation of lithium into FeWO4Cl. FeWO4Cl crystallize into a tetragonal system (space group P4 /nmm) with cell dimensions of a = 6.677(5) Angstrom and c = 5.270(5) A ngstrom, while lithium intercalation gives rise to the formation of a monoclinic phase (P2(1)/m) with cell dimensions of a = 7.050(0) Angstr om, b = 6.926(2) Angstrom, c = 5.043(0) Angstrom and beta = 92.54(2)de grees. Infrared (IR) spectroscopic analyses of FeWO4Cl show that the s ymmetry of the tetrahedral WO42- group in FeWO4Cl becomes reduced as t he lithium intercalate into its two-dimensional lattice, indicating an alternately ordered lithium occupancy of half of the octahedral inter layer sites. The effective magnetic moments of FeWO4Cl and LiFeWO4Cl w ere estimated to be 5.95 and 5.10 B.M., respectively, which can be att ributed to the selective reduction of a high-spin ferric ion to a high -spin ferrons one upon lithium intercalation. It was also found that t he two-dimensional magnetic property of FeWO4Cl was changed to a three -dimensional one in LiFeWO4Cl owing to the c-axis contraction.