Phase Transition Study by using ^<133>Cs and ^<207>Pb Nuclear Magnetic Resonance in a CsPbCl_3 Single Crystal (Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

概要

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The phase transitions of a ferroelastic CsPbCl_3 single crystal grown by using the Bridgman method have been investigated using ^<133>Cs and ^<207>Pb nuclear magnetic resonance (NMR). Two sets of seven-line ^<133>Cs NMR signals were obtained instead of a simple seven-line structure. From the experimental data, the ^<133>Cs NMR parameters were obtained in the temperature range from phase I to phase IV. These showed the same magnitudes for the quadrupole coupling constants and the asymmetry parameters for the resonance lines of the two sets, but with different orientations. Near the transition temperatures 37℃ and 47℃, the NMR parameter of the ^<133>Cs nucleus changed abruptly, which means that first-order phase transitions occurred at 37℃ and 47℃, whereas a second-order phase transition occurred at 42℃. In addition, the nuclear spin-lattice relaxation time of the Cs nucleus in this crystal revealed a discontinuity at 47℃ while the Pb relaxation time seems to be continuous in the temperature. The abrupt change in the ^<133>Cs relaxation time near 47℃ is due to the critical showing down of the soft mode. Our relaxation time results indicate that the phase transitions might be attributed to the dominant relaxation mechanism.
社団法人日本物理学会の論文
2004-02-15