Synthesis and properties of a new ? polymorph of Li3CrO4

Abstract

?-Li3CrO4, isostructural with ?-Li3PO4, has been synthesized by two routes. Reaction of Li2CO3 and Cr2O3 in a 5 : 1 mole ratio in flowing Ar at 800 �C yields ?-Li3CrO4, with a small amount of Li2O. The Li2CO3, seems to have two functions. It is an essential reactant and acts as a novel oxidant, promoting conversion of CrIII to CrV. Reaction of Li2CO3 and CrO3 in a 3 : 1 mole ratio in flowing Ar also gives phase-pure ?-Li3CrO4. Magnetic measurements show Curie?Weiss behaviour in the range 20?300 K with a magnetic moment of 1.70 �B consistent with CrV in tetrahedral coordination. Conductivity measurements show a modest level of electronic conduction.