ELECTRON-PARAMAGNETIC-RES STUDY OF THE FERROELECTRIC PHASE-TRANSITION IN T-2+ DOPED RBH2PO4

The electron paramagnetic resonance spectra of Tl**2** plus doped RbH//2PO//4 show at c OVER BAR PERPEND H OVER BAR //0 a large splitting which is proportional to the spontaneous polarization. The temperature dependence of the second moment of the individual EPR lines exhibits a huge anomalous increase at the paraelectric-ferroelectric transition temperature T//c which is related to the slowing down of the order parameter fluctuations below the rigid lattice linewidth and to the increase in the width of the local order parameter distribution function g(p) as T yields T//c from both sides.