Soft Synthesis Route and Characterization of Superparamagnetic Mn1/2Fe1/2(H2PO4)2·2H2O and Its Decomposed Product

Abstract

The superparamagnetic Mn1/2Fe1/2(H2PO4)2·2H2O was synthesized by a soft synthesis method using a Mn(c)−Fe(c)−H3PO4 system in water−acetone medium at ambient temperature. The synthesized Mn1/2Fe1/2(H2PO4)2·2H2O decomposed through the dehydration and the phosphate condensation reactions at high temperature and yielded binary manganese iron cyclotetraphosphate MnFeP4O12. The XRD and FTIR results of the synthesized Mn1/2Fe1/2(H2PO4)2·2H2O and the decomposed MnFeP4O12 indicate the pure monoclinic phase with space group P21/n and C2/c, respectively. The thermal behaviors and superparamagnetic properties of Mn1/2Fe1/2(H2PO4)2·2H2O and MnFeP4O12 in this work differed from the single compounds (M(H2PO4)2·2H2O and M2P4O12, where M = Mn, Fe) and the binary compounds (Mn0.5Fe0.5(H2PO4)2·xH2O) reported in previous works. The kinetic and thermodynamic functions for thermal decomposition of Mn1/2Fe1/2(H2PO4)2·2H2O were studied and confirmed as reaction mechanisms. Vibrational frequencies of breaking bonds in two thermal...