title: At last! The single-crystal X-ray structure of a naturally occurring sample of the ilmenite-type oxide FeCrO3.
abstract: A natural single crystal of the ferrimagnetic oxide FeCrO3, which was found in an opencast mine situated in the San Luis Potosí State in Mexico, has been characterized in order to elucidate some outstanding issues about the actual structure of this material. The single-crystal X-ray analysis unambiguously shows that transition metal cations are segregated in alternating layers normal to the threefold crystallographic axis, affording a structure isomorphous to that of ilmenite (FeTiO3), in the space group R3̅. The possible occurrence of cation antisite and vacancy defects is below the limit of detection available from X-ray data. Structural and magnetic results are in agreement with the coherent slow intergrowth of magnetic phases provided by the two antiferromagnetic corundum-type parent oxides Fe2O3 (hematite) and Cr2O3 (eskolaite). Our results are consistent with the most recent density functional theory (DFT) studies carried out on digital FeCrO3 [Sadat Nabi & Pentcheva (2011). Phys. Rev. B, 83, 214424], and suggest that synthetic samples of FeCrO3 might present a cation distribution different to that of the ilmenite structural type.
authors.affiliation: Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Edif. 105I Complejo de Ciencias CU, San Manuel, 72570 Puebla, Pue., Mexico.
authors.forename: María Ana
authors.initials: MA
authors.lastname: Pérez-Cruz
authors.affiliation: Centro de Química del Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif. F103 Complejo de Ciencias CU, San Manuel, 72570 Puebla, Pue., Mexico.
authors.forename: María de la Paz
authors.initials: Mde L
authors.lastname: Elizalde-González
authors.affiliation: Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior, Ciudad Universitaria, Coyoacán, 04510 México D.F., Mexico.
authors.forename: Roberto
authors.initials: R
authors.lastname: Escudero
authors.affiliation: Instituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue., Mexico.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bernès
authors.affiliation: Instituto de Física, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y 18 Sur, 72570 Puebla, Pue., Mexico.
authors.forename: Rutilo
authors.initials: R
authors.lastname: Silva-González
authors.affiliation: Centro de Química del Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edif. F103 Complejo de Ciencias CU, San Manuel, 72570 Puebla, Pue., Mexico.
authors.forename: Yasmi
authors.initials: Y
authors.lastname: Reyes-Ortega
keywords: double oxide; ilmenite; magnetism; mineral