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Phase Transition Studied by Nuclear Spin–Lattice Relaxation in a KHCO 3 Single Crystal
Author(s) -
Lim Ae Ran,
Jeong SeYoung
Publication year - 2001
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 - 10.1002/1521-3951(200108)226:2<413::aid-pssb413>3.0.co;2-#
Subject(s) - single crystal , phase transition , relaxation (psychology) , nuclear magnetic resonance , condensed matter physics , lattice (music) , spin–lattice relaxation , materials science , chemistry , physics , nuclear quadrupole resonance , psychology , social psychology , acoustics
The 1 H and 39 K spin–lattice relaxation times in a KHCO 3 single crystal grown by the slow evaporation method were investigated by employing a NMR spectrometer. The relaxation processes of 1 H and 39 K were described by a single exponential function. The large change in the relaxation time at 318 K indicates that the H and K ions are significantly affected during this transition. We know that the phase I to phase II transition is a first‐order phase transition. Experimental results show that the temperature dependences of the spin–lattice relaxation time behavior were quite similar for both nuclei. From these results the activation energies for the 1 H and 39 K nuclei were obtained and the values are similar for both nuclei in phases I and II. The temperature dependences of the spin–lattice relaxation rates of 39 K are proportional to T 4 and T 7 with Raman process dominated by the phonon mechanism below T c and above T c , respectively.