The effect of cobalt and copper substitution in Mn12-ac

Cobalt and copper have been doped successfully in dodecanuclear manganese acetate complex, [Mn12O12(CH3COO)16(H2O)4],2CH3COOH,4H2O without altering the crystal symmetry where Co and Cu replaces the Mn sites. The substitution of Co and Cu ions indicates the increase of blocking temperature, while the over all magnitude of the magnetization has been reduced by the substitution in the temperature range 2-50 K measured at 1 T. The nature of field dependence of magnetization do not affect considerably. On the other hand, relaxation rate changes by the substitution of Co and Cu below the blocking temperature at external magnetic field 0.95 and 1 T