@article{oai:u-ryukyu.repo.nii.ac.jp:02009694,
 author = {Niki, Haruo and Yogi, Mamoru and Tamanaha, Mikako and Seto, Urara and Hashimoto, Masao and Terao, Hiromitsu},
 issue = {6-7},
 journal = {Zeitschrift für Naturforschung A},
 month = {Jul},
 note = {The temperature dependences of T_1 and T_2 of ^<81>Br and ^<121>Sb NQR have been measured in order to study the phase transition at T_c = 224 K as well as the crystal dynamics in 4-aminopyridinium tetrabromoantimonate(III) (4-NH_2PyHSbBr_4). The temperature dependence of T_1 of ^<81>Br and ^<121>Sb NQR follows the usual T^2 law in the range from 80 to 120 K. T_1 is dominated by fluctuations of the EFG at the Br and Sb nuclei due to lattice vibrations. The T_1 vs. 1/T curves in the region between about 120 and 140 K can be described by exponential curves. The activation energies of motions obtained from these curves are similar to those from proton NMR. The exponential changes of T_1 of Br and Sb NQR are attributable to fluctuations caused by the thermal motion of 4-NH_2PyH cations. Echo signals of Br and Sb NQR in the low temperature phase could not be detected at temperatures higher than 145 and 150 K, respectively, because the S/N ratios became poor owing to the very short T_2. The echo signals could also not be detected at temperatures above T_c because of the short T_2., 論文},
 pages = {469--472},
 title = {Bromine and Antimony NQR of 4-Aminopyridinium Tetrabromoantimonate(III)},
 volume = {57},
 year = {2002}
}