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Title :Bromine and Antimony NQR of 4-Aminopyridinium Tetrabromoantimonate(III)
Authors :Niki, Haruo
Yogi, Mamoru
Tamanaha, Mikako
Seto, Urara
Hashimoto, Masao
Terao, Hiromitsu
Issue Date :1-Jul-2002
Abstract :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.
URL :https://doi.org/10.1515/zna-2002-6-733
Type Local :雑誌掲載論文
ISSN :0932-0784
Publisher :Verlag der Zeitschrift für Naturforschung
URI :http://hdl.handle.net/20.500.12000/40985
Citation :Zeitschrift für Naturforschung A Vol.57 no.6-7 p.469 -472
Appears in Collections:Peer-reviewed Journal Articles (Faculty of Science)

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