Title: FERROELECTRIC PHASE TRANSITION IN LEAD GERMANATE Pb_{5}Ge_{3}O_{11} STUDIED BY ESR OF Gd^{3+} PROBE
Author(s): M.P.Trubitsyn, M.D.Volnianskii, A.S.Ermakov, V.G.Linnik (Dnipropetrovsk State University, Department of Physics, 13 Naukovyi Lane, Dnipropetrovsk, 320625 Ukraine}

ESR spectra of Gd$^{3+}$ probe have been studied in the range of ferroelectric phase transition $T_{\rm C}$=451 K in lead germanate Pb$_5$Ge$_3$O$_{11}$. Measurements of ESR line position have shown that local order parameter behaves in accordance with the mean field theory approach in a broad ($\sim$150 K) temperature interval below $T_{\rm C}$. Anomalous line width broadening observed around $T_{\rm C}$ can be associated with a quasi-elastic central peak component of excitation spectrum, observed earlier using a light scattering experiment and attributed to static symmetry-breaking defects.

Comments: Figs. 4, Refs. 19, Tabs. 0.