(CU,M)2P2O7 - M=MN, CO - SYNTHESIS, MAGNETISM AND SOLID-STATE STRUCTURES OF CU0.92MN1.08P2O7 AND CUCOP2O7

The solid solution Cu2-xMxP2O7; 0 less-than-or-equal-to x less-than-or-equal-to 2, (M=Mn, Co), has been synthesized in powder form and found to consist of a continuous phase of type, beta-Cu2P2O7 in the domain 0.05 less-than-or-equal-to x less-than-or-equal-to 2 for M=Mn and 0.04 less-than-or-equal-to x less-than-or-equal-to 1.20 for M=Co. Single crystal studies of Cu0.92Mn1.08P2O7 (x=1.08) and CuCoP2O7 confirm the similarity. For M=Mn, Cu2+ and Mn2+ ions share metal sites whereas for M=Co2+, Cu2+ and Co2+ occupy different sites. Magnetic properties of the solid solution indicate the existence of antiferromagnetic interactions for both solids. For x=1, noncompensation of magnetic sublatices is evident and a well defined transition to a state of three dimensional order is noted by specific heat measurements.