We present the temperature dependence of shear and longitudinal elastic constants in a'-NaV2O5. For the longitudinal c22 and c33 modes we find anomalies at Tc in contrast to the Spin Peierls substance CuGeO3 where only the longitudinal mode along the chain shows a pronounced effect at TSP. The c66 shear mode (propagation along the chain in b-direction polarization in a-direction) shows strong softening of 12%. Such a large effect is absent for all shear modes in CuGeO3. We can interpret this softening with a coupling of the exy symmetry strain to the charge fluctuation of B1g symmetry. We give the possible low temperature charge distribution.
@article{arxiv.cond-mat/9904346,
title = {Elastic Constants and Charge Ordering in a'-NaV2O5},
author = {H. Schwenk and S. Zherlitsyn and B. Luethi and E. Morre and C. Geibel},
journal= {arXiv preprint arXiv:cond-mat/9904346},
year = {2009}
}