Temperature-Induced Phase Transitions of Vivianite: In Situ Analysis of a Redox-Driven Crystallization.

ABSTRACT: We document a solid-state, temperature-dependent (25-700 °C), multistage redox transformation of crystalline ferrous iron phosphate, vivianite (Fe₃(PO₄)₂·8H₂O). Under anoxic conditions, vivianite breaks down at T > 250 °C into an anhydrous, amorphous intermediate Fe₃(PO₄)₂ phase, yet the bulk shape and morphology of the starting vivianite crystals were retained. This amorphous intermediate phase remained stable until T > 500 °C, after which a redox-dependent crystallization into two different minerals was observed. Under anoxic conditions, the amorphous ferrous intermediate (Fe₃(PO₄)₂) transformed into the crystalline ferrous phosphate (graftonite, (Fe²⁺)

SUBMITTER: Paskin A 

PROVIDER: S-EPMC12442088 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature