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ESR Study of the Monoclinic—Orthorhombic Phase Transition in Neodymium Pentaphosphates
Author(s) -
Parrot R.,
Canny B.
Publication year - 1982
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.2221100114
Subject(s) - tensor (intrinsic definition) , orthorhombic crystal system , monoclinic crystal system , neodymium , symmetry (geometry) , principal axis theorem , condensed matter physics , rotation (mathematics) , phase transition , electron paramagnetic resonance , physics , crystallography , nuclear magnetic resonance , chemistry , crystal structure , quantum mechanics , mathematics , geometry , laser
Very accurate electron spin resonance measurements are performed on Gd 3+ impurities in single‐domain crystals of neodymium pentaphosphates. It is shown that the transition from C s symmetry above the critical temperature ( T c = 421 K) to C 1 symmetry below T c can be interpreted in terms of a temperature‐dependent three‐dimensional rotation R(α, β, γ) of the principal axes of the tensor D . The Euler's angle β( T ) and (α + γ) ( T ) are given by β(degrees) = 0.415 ( T c − T ) 1/2 − 0.007 ( T c − T ) and (α + γ) (degrees) = 0.11 ( T c − T ) 1/2 . Finally, the temperature‐dependent rotation of the tensor D is compared to the rotation of the quadrupolar tensor (tensor Q ) appearing in the multipolar expansion of the internal crystal field.