Low-temperature charge ordering inSr14Cu24O41

Synchrotron x-ray measurements were made between 20–300 K on single crystals of ${\mathrm{Sr}}_{14}{\mathrm{Cu}}_{24}{\mathrm{O}}_{41}$, which has a quasi-one-dimensional chain and ladder structure, in order to investigate possible charge-ordering effects in the CuO${}_2$ chains as indicated by recent NMR studies. At 50 K a few very weak satellite peaks were observed at $\mathrm{}\left(00l\right)\mathrm{}$ positions corresponding to a fourfold increase in periodicity along the chain axis. These peaks decreased in intensity with increasing temperature, and eventually disappeared close to 300 K. The observations were interpreted in terms of a charge-ordered model involving both dimerization between two next-nearest-neighbor ${\mathrm{Cu}}^{2+}$ ions surrounding a ${\mathrm{Cu}}^{3+}$ ion on a Zhang-Rice singlet site, and dimerization between nearest-neighbor ${\mathrm{Cu}}^{2+}$ ions.