Mössbauer studies on the thermolysis of manganese tris(malonato)ferrate(III)hexahydrate

Characterization of the citrate precursor, used for synthesis of nanosized Mg-Zn ferrites

“…The frequency shift of the IR-active bands, with respect to the theoretical positions from 3150 to 3213 cm -1 and from1400 to 1437 cm -1 were assigned to formation of hydrogen bonds in the sample "Precursor" with NH 4 + participation [15]. The formation of citrate complexes is proven by the doublets located at 1617 and 1578 cm -1 due to antisymmetric stretching vibration, and at 1415 and 1399 cm -1 due to symmetrical stretching vibration of ionized carboxylate groups [5,6,10,13]. The band positions are close to the ones cited in the analogous citrate precursors for ferrites, which are listed in Table 1.…”

“…As a result, a bidentate coordination could be assigned to Fe(III) ions. A sharp and distinct band at 566 cm -1 ascertains the bonding of Fe(III) to the citrate ligands in octahedral geometry [5,6]. Probably, in the unidentate type of coordination, the ions of Zn(II) and Mg(II) are involved.…”

“…The citrate precursors are widely used to produce a number of multi-component, phase-homogeneous nanosized ferrites [2][3][4][5][6][7][8]. According to its creators, the technique comprises in the obtaining of amorphous mixture retaining all the necessary metallic ions and citric acid in pure homogeneity [2].…”

“…The researchers in the next study described the citrate precursor for Ni 2 Fe 2 O 4 as a linear-type polymer [(C 6 H 6 O 7 ) 4 NiFe 2 ] n [7]. The complexes described in [6,7] consist of citrate anions C 6 H 5 O 7 3-, without information about the usage of a base. In [8], ammonium hydroxide was used, but the possibility for participation of NH 4 + ions in the formed complex was not discussed.…”

“…The complex compounds that form the ions of magnesium and zinc, depend on the pH rate and the amount of citric acid. According to the dissociation scheme of citric acid [9,10], at a pH rate of about 6 -, where M=Zn(II) and Mg(II). The coordination chemistry of citric acid -Fe(III) system is studied taking into account the biological importance only [10][11][12].…”