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Evidence for zero‐field fluctuations in Cr 3+ near the phase transition in NH 4 Al(SO 4 ) 2 12 H 2 0
Author(s) -
Owens F. J.
Publication year - 1977
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.2220790228
Subject(s) - ion , electron paramagnetic resonance , phase transition , field (mathematics) , condensed matter physics , symmetry (geometry) , phase (matter) , chemistry , zero (linguistics) , resonance (particle physics) , coupling (piping) , paramagnetism , tensor (intrinsic definition) , nuclear magnetic resonance , physics , atomic physics , materials science , linguistics , geometry , mathematics , philosophy , organic chemistry , pure mathematics , metallurgy
The effect of the phase transition of NH 4 Al(SO 4 ) 2 12 H 2 O on the EPR of the Cr 3+ ion is studied. The axial zero‐field tensor shows a strong linear temperature dependence with a change in slope occurring at −160°C which correlates to the onset of a marked broadening of the high and low field resonances as well as with an unusual increase in the intensity of the center resonance. The effects are attributed to fluctuations in the local symmetry of the H 2 O molecules about the Cr 3+ ion. The strong temperature dependence of D is argued to be due to an unusually large coupling of the paramagnetic ion to local vibrations of the complex.