Investigations of Phase Transitions in (NH₄)₃H(SO₄)₂Crystal by Means of Mn²⁺EPR Spectra

Abstract

EPR of Mn2+ impurity ion in the (ΝΗ4 )3 Η(SO4 )2 crystal is studied in the temperature range 80-420 K. It is shown that Mn2 + substitutes NH+4 (I) ion and is coordinated in deformed oxygen octahedron in which takes two "off center" positions. Its spin-Hamiltonian parameters and direction cosines of crystal field are determined. The successive EPR line splitting for three phase transitions is discussed.

Proton dynamics in Rb3H(SO4)2doped with Mn2+studied by EPR and impedance spectroscopy

“…Similarly as for the K 3 H(SO 4 ) 2 and (NH 4 ) 3 H(SO 4 ) 2 crystals [10,11], the direction cosines indicate the same mechanism of the excess charge compensation. In the Rb 3 H(SO 4 ) 2 crystals the Mn 2+ ion replaces the Rb + (I) ion and its positive excess charge is compensated by a proton vacancy.…”