화학공학소재연구정보센터
Inorganic Chemistry, Vol.60, No.6, 3719-3728, 2021
Molecular Level Synthesis of InFeO3 and InFeO3/Fe2O3 Nanocomposites
New heterometallic In-Fe alkoxides [InFe-((OBu)-Bu-t)(4)(PyTFP)(2)] (1), [InFe2(O(neo)Pen)(9)(Py)] (2), and [InFe3(O(neo)Pen)(12)] (3) were synthesized and structurally characterized. The arrangement of metal centers in mixed-metal framework was governed by the In:Fe ratio and the coordination preferences of Fe(III) and In(III) centers to be in tetrahedral and octahedral environments, respectively. 3 displayed a star-shaped socalled "Mitsubishi" motif with the central In atom coordinated with three tetrahedral {Fe(O(neo)Pen)(4)}(-) anionic units. The deterministic structural influence of the larger In atom was evident in 1 and 2 which displayed the coordination of neutral coligands to achieve the desired coordination number. Thermal decomposition studies of compounds 1-3 under inert conditions with subsequent powder diffraction studies revealed the formation of Fe2O3 and In2O3 in the case of 3 and 2, whereas 1 intriguingly produced elemental In and Fe. In contrary, the thermal decomposition of 1-3 under ambient conditions produced a ternary oxide, InFeO3, with additional Fe2O3 present as a secondary phase in a different stoichiometric ratio predetermined through the In:Fe ratio in 2 and 3. The intimate mixing of different phases in InFeO3/Fe2O3 nanocomposites was confirmed by transmission electron microscopy of solid residues obtained after the decomposition of 1 and 2. The pure InFeO3 particles demonstrated ferromagnetic anomalies around 170 K as determined by temperature-dependent field-cooled and zero-field-cooled magnetization experiments. A first-order magnetic transition with an increase in the ZFC measurements was explained by temperature-induced reduction of the Fe-Fe distance and the corresponding increase in superexchange.