Synthesis and crystal structure of the high-pressure iron borate α-FeB 2O 4

• Published in: Journal of solid state chemistry Vol. 181; no. 8; pp. 2092 - 2098
• Main Authors: Knyrim, Johanna S., Huppertz, Hubert
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 2008
• Subjects: Borate; Crystal structure; High-pressure; Multianvil; Multianvil; High-pressure; Borate; Crystal structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2008.05.016

The high-pressure iron borate α-FeB 2O 4 was synthesized under high-pressure and high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 °C. The monoclinic iron borate crystallizes with eight formula units in the space group P2 1/ c with the lattice parameters a=715.2(2), b=744.5(2), c=862.3(2) pm, and β=94.71(3)°. The compound is built up exclusively from corner-sharing BO 4-tetrahedra, isotypic to the monoclinic phases β-SrGa 2O 4, CaAl 2O 4-II, and CaGa 2O 4. Additionally, the structure is closely related to the orthorhombic compound BaFe 2O 4. The structure consists of layers of six-membered rings, which are interconnected to a three-dimensional network. The iron cations are coordinated by six and seven oxygen atoms. Next to synthesis and crystal structure of the new high-pressure borate, structural coherences to other structure types are discussed. High-pressure/high-temperature synthesis (multianvil technique) led to the new phase α-FeB 2O 4, which is exclusively built up from corner-sharing BO 4-tetrahedra, isotypic to the monoclinic phases β-SrGa 2O 4, CaAl 2O 4-II, and CaGa 2O 4. [Display omitted]