We present for the first time the evidence for a thermodynamically stable incommensurate elongated-triangle (ELT) phase in quartz observed by transmission electron microscopy at structural α−β transition. The phase sequence on cooling is: uniform β phase - stripe incommensurate phase (ferroelastic) - incommensurate equilateral-triangle (EQT) phase (ferroelectric) - incommensurate ELT (ferroelectric and ferroelastic) - uniform α phase. The ELT blocks could be responsible for the large light scattering in the vicinity of α−β transition.
@article{arxiv.cond-mat/9511002,
title = {New Incommensurate Elongated-Triangle Phase in Quartz},
author = {P. Saint-Gregoire and I. Luk'yanchuk and E. Snoeck and C. Roucau and V. Janovec},
journal= {arXiv preprint arXiv:cond-mat/9511002},
year = {2008}
}