X-ray crystal structure analysis and the Ru valence of Ba4Ru3O10 single crystals

TL;DR

This study investigates the crystal structure and Ru valence states in Ba4Ru3O10 single crystals, revealing charge disproportionation within Ru3O12 trimers and analyzing the phase transition at 105 K.

Contribution

It provides detailed structural data across temperatures and links charge disproportionation to molecular orbital formation in the trimers, advancing understanding of electronic states in this material.

Findings

Charge disproportionation occurs within Ru3O12 trimers at room temperature.

The crystal structure remains orthorhombic across the antiferromagnetic transition.

Long Ru-O distances suggest significant electronic localization.

Abstract

We present the single-crystalline x-ray diffraction study on the Ba4Ru3O10 consisting of the corner-shared Ru3O12 trimers. The crystal structure is re-determined from 78 to 300 K across an antiferromagnetic transition at 105 K. The orthorhombic symmetry (Cmca, space group No. 64) is preserved at all temperatures measured. This structure presents exceptionally long Ru-O distances characterized by a significant distribution within the Ru3O12 trimer. A bond valence sum calculation suggests that the charge disproportionation within the Ru3O12 trimer emerges even at room temperature, which we ascribe to molecular orbital formation in the Ru3O12 trimer, as supported by recent theoretical calculations. Based on the analyzed crystal structure, the electronic states and the nature of the phase transition at 105 K are discussed.