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ESR Study of a Cr 5+ Centre in Ferroelectric Ammonium Sulphate
Author(s) -
Manjunath C. V.,
Srinivasan R.
Publication year - 1978
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220870147
Subject(s) - electron paramagnetic resonance , ferroelectricity , unpaired electron , ammonium , crystallography , nuclear magnetic resonance , ground state , proton , chemistry , materials science , atomic physics , physics , quantum mechanics , dielectric , optoelectronics , organic chemistry
X‐band electron spin resonance (ESR) studies of (CrO 4 ) 2‐ doped, X‐irradiated single crystals of ferroelectric ammonium sulphate ((NH 4 ) 2 SO 4 , T C = 223 K) at 300 and 208 K are reported. The paramagnetic centre responsible for the ESR spectrum is identified to be Cr 5+ . Superhyperfine interaction of the unpaired electron with two equivalent protons is observed. The spin‐Hamiltonian parameters which are nearly axial at 300 K, with g ‖ < g ⟂ indicating a d x 2 – y 2orbital ground state, acquired rhombic character below T C indicating a distortion of the sulphate tetrahedron. An increase in the value of the proton superhyperfine constant in the ferroelectric phase is indicative of stronger hydrogen bonding.