A novel route for FePO4 olivine synthesis from sarcopside oxidation

Comprehensive Study of Oxygen Storage in YbFe2O4+x (x ≤ 0.5): Unprecedented Coexistence of FeOn Polyhedra in One Single Phase

“…Three distinct main structural routes are associated with the Fe 2+ →Fe 3+ oxidation in solid oxides: the filling of oxygen vacancies with “minor” reconstructive changes of the cationic sub-lattice sometimes in absence of any thermal activation, e.g., the slow oxidation of magnetite Fe 3 O 4 into maghemite γ-Fe 2 O 3 with conservation of the spinelle structure, and the spontaneous oxidation of YBaFe +2.25 4 O 7.0 into YBaFe +2.5 4 O 7.5 at room temperature and further oxidation on post-annealing the topochemical oxidation by exsolution of Fe 2 O 3 starting from Fe 2+ -based oxo-anion compounds, e.g., Fe 3 (PO 4 ) 2 →Fe 2 (PO 4 ) 2 , LiFe­(PO 4 ) → LiFe 1‑ x (PO 4 ), BaFe 2 (PO 4 ) 2 → BaFe 1.33 (PO 4 ) 2 . , It involves long Fe diffusion paths generally activated around ∼300 °C in the case of iron phosphates. the restacking of the cation-based layers concerned in this work. This process is rare but was recently reported during the reversible reduction/re-oxidation of the layered YMnO 2.5 into YMnO 3 , see Figure a,b.…”

Oxidative decomposition products of synthetic NaFePO4 marićite: nano-textural and electrochemical characterization

“…Iron expulsion and oxidation is found to occur through an isomorphic process where BaFe2-x(PO4)2 partially to fully oxidized BaFe2-x(PO4)2 phases (with 0 < x < 2/3) . Similarly, Crouzet et al (2016) reported on the covering of FePO4…”

“…Similar process has been described with Fe2SiO4, fayalite, which transforms upon heating in air into a structurally defective Fe 3+ -bearing olivine group silicate, laihunite (Kondoh et al, 1985). Similarly, Crouzet et al, (2016) have showed that heating in air of synthetic sarcopside, Fe 2+ 3PO4, which also writes (Fe 2+ 3/2, 1/2)2PO4 in order to emphasize its olivinerelated structure, leads to the formation of Fe 3+ PO4 along with Fe2O3 nanoparticles; Fe 3+ PO4 displays an heterosite structure which is also based on an olivine atomic arrangement (Eventoff et al, 1972).…”

Mineral-Inspired Materials: Synthetic Phosphate Analogues for Battery Applications

“…The observed changes in the reaction mechanism result in profound difference in the unit cell parameters of the triphylite phase, particle morphology, and electrochemical properties of the obtained LiFePO4 samples [35]. According to [63], direct thermal oxidation of sarcopside, Fe3(PO4)2, above 450 °С, makes it possible to obtain heterosite, FePO4, according to the reaction Fe3(PO4)2 + ¾ O2 → 2 FePO4 + ½ Fe2O3, which leads to the extraction of iron from the sarcopside structure. The authors note that the oxidized product demonstrates electrochemical performances consistent with those of heterosite, FePO4.…”

“…According to [63], direct thermal oxidation of sarcopside, Fe 3 (PO 4 ) 2 , above 450 • C, makes it possible to obtain heterosite, FePO 4 , according to the reaction Fe 3 (PO 4 ) 2 + 3 /4 O 2 → 2 FePO 4 + 1 /2 Fe 2 O 3 , which leads to the extraction of iron from the sarcopside structure. The authors note that the oxidized product demonstrates electrochemical performances consistent with those of heterosite, FePO 4 .…”