STRUCTURE AND ANTIFERROMAGNETIC PROPERTIES OF A MIXED-VALENT MOLYBDENO MONOPHOSPHATE OF LITHIUM

A lithium mixed valent molybdenophosphate (LiMo2MoP3O16)-Mo-V-P-VI has been synthesized for the first time. This phase isotypic to NaMo3P3O1 6 is triclinic with 1)Angstrom,b=7.709(1)Angstrom,c=12.529(1)Angstrom, alpha=80.03(1)degrees, beta=77.62(1)degrees, gamma=81.80(1)degrees; i ts framework very similar to that of the sodium phase, is characterize d by monophosphate group linked to MoO6 octahedra and MoO5 trigonal bi pyramids, occupied by Mo(V) and Mo(VI) respectively. It differs from t he Na and Ag phases by the position of the lithium, that is located ne ar the basal plane of a tetragonal pyramid. The investigation of its m agnetic properties, shows that (LiMo2MoP3O16)-Mo-V-P-VI, exhibits an a ntiferromagnetic ordering below 100K, which can be interpreted as the result of two opposite orientations of the Mo(V) spins on the two octa hedral sites, Mo(1) and Mo(2).