The two-fold superstructure of titanium(III)-oxybromide at T = 17.5 K

TL;DR

This study reveals that titanium(III)-oxybromide (TiOBr) adopts a two-fold superstructure at 17.5 K, similar to TiOCl, indicating a spin-Peierls state with reduced modulations and interactions.

Contribution

The paper provides the first detailed low-temperature structure of TiOBr, showing its isostructural relationship to TiOCl and confirming its spin-Peierls state at low temperatures.

Findings

TiOBr has a two-fold superstructure at 17.5 K.

TiOBr is isostructural to TiOCl at low temperatures.

The spin-Peierls state in TiOBr has smaller modulations than in TiOCl.

Abstract

The low-temperature (T = 17.5 K) structure of titanium(III)-oxybromide, TiOBr, is reported as a two-fold superstructure of the crystal structure at room temperature. Weak superlattice reflections could be measured with synchrotron radiation x-rays, and they were analysed by structure refinements employing superspace techniques. Both the low temperature and room temperature tructures of TiOBr are isostructural to the corresponding structures of TiOCl. The results indicate that at low temperatures TiOBr is in a spin-Peierls state similar to TiOCl, but with the modulations and relevant interactions smaller than in the latter compound.