Displacive Movement of the Radical in TGS near the Curie Point

概要

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ESR spectra of γ-irradiated TGS were observed in both ferroelectric and paraelectric phases. The hyperfine splitting tensors of the rotating β-protons and the α-proton in the radical NH_3CHCOO^-, were determined. The hfs tensor of the β-protons was varied when the crystal passed through the Curie point. From the temperature dependence of the spectrum, the frequency factor, f_0 and the activation energy E of the rotating β protons were determined to be 5×10^<11> sec^<-1> and 0.17 eV, respectively. Near and above the Curie point, the experimental curve of log τ versus 1/T deviates from the relation 1/τ=f_0exp(-E/kT). This means that near and above the Curie point, glycines 2 and 3 are placed at the positions of point symmetry as if they make a displacive transition and the spectral lines are superimposed. It was also found that the ESR spectrum of the radical CH_2COO^- disappeared abruptly at about 80℃, suggesting the decomposition of the radical.
社団法人日本物理学会の論文
1972-03-05