Coprecipitation of Oxalates: An Easy and Reproducible Wet‐Chemistry Synthesis Route for Transition‐Metal Ferrites

Abstract

In this work, an easy, quick and reproducible wet-synthesis coprecipitation route starting from oxalate precursors was optimised to synthesise cobalt, nickel, zinc and magnesium spinel ferrites CoFe2O4, NiFe2O4, ZnFe2O4 and MgFe2O4, as well as the manganese perovskite ferrite MnFeO3. Crystalline purity and crystallite sizes ranging from 30 to 190 nm were investigated by means of powder X-ray diffraction, and uniform morphology of the particles was shown through transmission electron microscopy. The chosen synthetic route afforded an excellent stoichiometric control over the products, as confirmed by combined X-ray photoelectron spectroscopy and inductively coupled plasma atomic emission spectroscopy analyses. The site geometry, degree of inversion in the spinels and chemical environments in the ferrites were explored by Mössbauer spectroscopy. The thermal evolution of the compounds during calcination and the decomposition pattern of the oxalates were studied through differential scanning calorimetry coupled with thermogravimetric analysis as well as in situ temperature-programmed X-ray diffraction. Magnetic properties of these oxides, as well as the transition of the perovskite from paramagnetic to ferrimagnetic behaviour at low temperatures, were investigated by superconducting quantum interferometer magnetometr

Photo-Fenton degradation of ammonia via a manganese–iron double-active component catalyst of graphene–manganese ferrite under visible light

“…The peaks of Mn 2p in Table 2 obviously broadened after the photocatalytic reaction, and the signal at 654.29 eV appeared as a new peak, thereby clearly proving the presence of Mn 3+ [45,46]. The further studies showed, after photocatalytic reaction finished, the XPS spectrum of Mn 2p was deconvoluted into 6 peaks (Fig.…”

Synthesis of Cobalt-Based Nanomaterials from Organic Precursors

“…by a wet-synthesis coprecipitation route starting from iron(III) nitrate, cobalt(II) chloride and oxalic acid in order to prepare the oxalate precursors. The precipitate was centrifuged, dried and calcined at 873 or 1173 K for 5 h in air [30]. Many researchers used the redox method to synthesize the carboxylate precursors (oxalate, malonate, succinate, etc.)…”

“…According to XPS and Mössbauer results, the as-synthesized compounds contained surface iron in oxidation state (III) and not in (II). The TPR result showed that the reduction process took place at 700-1173 K and resulted in the reduction of Co(II) and Fe(III) cations to a metallic state [30]. In addition, some researchers have studied the synthesis of [34], with the use of longer chain precursors [31] and the increase of the annealing temperature [36].…”

“…Additionally, Ashouri et al employed MOF-derived Co 3 O 4 for the catalytic oxidation and epoxidation of olefins and reported that the catalyst showed good catalytic stability and reusability [49]. Diodati et al synthesized and used CoFe 2 O 4 in the catalytic oxidation of methane and concluded that the catalytic reaction took place at lower temperature (by about 300 K) in comparison to the uncatalyzed reaction while the cobalt ferrite catalyst exhibited good stability [30]. Gingasu et al synthesized cobalt chromite catalysts via thermal decomposition of tartrate and gluconate precursors and reported that gluconate-derived CoCr 2 O 4 was the best catalyst for total oxidation of methane exhibiting high activity and CO 2 selectivity [41].…”

Europium Luminescence as a Structural Probe: Structure‐Dependent Changes in Eu3+‐Substituted Th(C2O4)2·xH2O (x = 6, 2, and 0)

“…Along with the above-mentioned technological applications, these metal oxalates are also important precursors for the synthesis of micro-or nanostructured metal oxides such as manganese oxide, [20] iron oxide, [21] cobalt oxide, [22] nickel oxide, [23,24] copper oxide, [25] zinc oxide, [26] zirconium oxide, [27] and thorium(IV) oxide. [28,29] [30] Thorium(IV) oxalate is an important component for the nuclear industry as it is used in the synthesis of thorium(IV) oxide, which is a fertile material and is used as a blanket material in nuclear reactors. Thorium(IV) oxalate incorporated into a silica gel matrix is proposed to be a new sorbent for the removal of americium from oxalic acid/nitric acid solutions.…”