Raman study of molecular motions in relation to phase transitions in [Ni(NH3)6](NO3)2

AbstractThe temperature dependence of 35C1, 81Br, and 127I NQR frequencies and 1Hspin-lattice relaxation times (T1) for CH3NH3PbX3 (X = Cl, Br, I) was measured through the successive phase transitions in these solids. The isotropic reorientation of the CH3NH3 ions takes place in the higher-temperature phases (tetragonal [I4/mcm] and cubic) of the three salts (Ea= 11 kJ mol -1). T1's in the lowest-temperature phases (orthorhombic) indicate that the cations undergo correlated C3-reorientation in the chloride (Ea = 5.45 kJ mol -1)and in the iodide (Ea = 5.80 kJ mol -1, whereas correlated (Ea = 2.40 kJ mol-1) and uncorrected (Ea = 7.50 kJ mol-1) C3- reorientations are excited in the bromide. It is also revealed that the rotational tunneling of the cations governs T1 at lowtemperature region in the orthorhombic phases of these salts

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Molecular Motions and Phase Transitions in Plastic Closocarboranes

Magnetic Resonance and Related Phenomena ◽

10.1007/978-3-642-81344-3_390 ◽

1979 ◽

pp. 454-454 ◽

Cited By ~ 3

Author(s):

A. L. Blumenfeld ◽

E. I. Fedin

Keyword(s):

Phase Transitions ◽

Molecular Motions

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Raman study of phase transitions in compressed methane using moissanite anvil cells

Physical Review B ◽

10.1103/physrevb.84.104110 ◽

2011 ◽

Vol 84 (10) ◽

Cited By ~ 12

Author(s):

Pei-Nan Chen ◽

Chang-Sheng Zha ◽

Xiao-Jia Chen ◽

Jinfu Shu ◽

Russell J. Hemley ◽

...

Keyword(s):

Phase Transitions ◽

Raman Study

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X-ray diffraction and Raman study of DL-alanine at high pressure: revision of phase transitions

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768112028972 ◽

2012 ◽

Vol 68 (4) ◽

pp. 412-423 ◽

Cited By ~ 24

Author(s):

Nikolay A. Tumanov ◽

Elena V. Boldyreva

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Structural Phase ◽

Group Symmetry ◽

Second Phase ◽

Structural Phase Transitions ◽

X Ray Diffraction ◽

X Ray ◽

Cell Parameters ◽

Raman Study

The effect of pressure on DL-alanine has been studied by X-ray powder diffraction (up to 8.3 GPa), single-crystal X-ray diffraction and Raman spectroscopy (up to ∼ 6 GPa). No structural phase transitions have been observed. At ∼ 1.5–2 GPa, cell parameters b and c become accidentally equal to each other, but the space-group symmetry does not change. There is no phase transition between 1.7 and 2.3 GPa, contrary to what has been reported earlier [Belo et al. (2010). Vibr. Spectrosc. 54, 107–111]. The presence of the second phase transition, which was claimed to appear within the pressure range from 6.0 to 7.3 GPa (Belo et al., 2010), is also argued. The changes in the Raman spectra have been shown to be continuous in all the pressure ranges studied.

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