Valence fluctuations in Sn(Pb)${}_2$P${}_2$S${}_6$ ferroelectrics

R. Yevych, V. Haborets, M. Medulych +5

The valence fluctuations which are related to the charge disproportionation of phosphorous ions $P^{4+}+P^{4+}\to P^{3+}+P^{5+}$ are the origin of ferroelectric and qua…