排序方式: 共有1条查询结果,搜索用时 0 毫秒
1
1.
HARUIO NIKI HIROAKI KINJOU TAICHI FUKUMURA HIROMITSU TERAO MAMI YOSHIDA MASAO HASHIMOTO 《Hyperfine Interactions》2004,159(1-4):193-197
Four 81Br NQR lines in 4-NH2C5H4NHBiBr4·H2O were observed in the temperature range between 77 and ca. 380 K; with increasing temperatures the respective sets of higher
and lower two resonance lines coalesced into single lines discontinuously at 274 K, showing the occurrence of a first-order
type phase transition of this crystal. The transition was confirmed with heat anomaly on a DTA curve. Each higher and lower
line of high-temperature phase is assignable to the terminal Br atoms and the bridging ones of one-dimensional poly anions
(BiBr4
−)
n
in the crystal structure (C2/c), which was investigated by a X-ray structure analysis at room temperature. The 1/T
1 temperature dependence of 81Br NQR follows the usual T
2 law in the temperature range between 77 and ca. 140 K, being explained by fluctuation of the EFG at Br nucleus due to lattice
vibrations. The T
1 vs. 1/T curve in the temperature range between about 160 and 190 K was describable by the exponential curves, allowing us the estimation
of activation energies. These exponential behaviors of T
1 of 81Br NQR are attributable to the fluctuations caused by the thermal motion of 4-NH2C5H4H+ ions. Echo signals of the 81Br NQR could not be detected above 190 K owing to poor S/N with very short T
2. 相似文献
1