ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Polymorphism of anhydrous iron(II) oxalate

Vítězslav Heger, Josef Kopp, Vít Procházka, and Petr Novák

Department of Experimental Physics, Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic

E-mail: v.prochazka@upol.cz

Received: 22 December 2022  Accepted: 28 September 2023

Abstract:

Recently, iron(II) oxalate has experienced a renewed interest due to their newly found application in lithium-ion batteries. Lithium is expected to be embedded between the oxalate sheets, dramatically increasing the need to understand the oxalate structure. Despite being known for decades, the discrepancies still exist regarding the anhydrous iron(II) oxalate. In this work, we explore the dehydration process of both α-FeC₂O₄·2H₂O and β-FeC₂O₄·2H₂O polymorphs at different heating rates and calcination temperatures by X-ray powder diffraction, Mössbauer spectroscopy and scanning electron microscopy. After dehydration, iron(II) oxalates formed two polymorphs with different XRD patterns: α-FeC₂O₄ with sharp and narrow diffraction lines and β-FeC₂O₄ with very broadened lines, which were attributed to the monoclinic structure with space group P2₁/n.

Keywords: Iron(II) oxalate; Crystal structure; Thermal decomposition; X-ray powder diffraction; Mössbauer spectroscopy

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03122-6

Chemical Papers 78 (1) 13–22 (2024)