Motions of Methylammonium Ions in (CH3NH3)2ZnBr4 Crystals Studied by 1H NMR and Thermal Measurements

1990 ◽  
Vol 45 (7) ◽  
pp. 923-927
Author(s):  
Hiroyuki Ishida ◽  
Kentaro Takagi ◽  
Tadashi Iwachido
Keyword(s):  
Solid Phase ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Self Diffusion ◽  
Spin Lattice ◽  
H Nmr

AbstractMeasurements of the 1H spin-lattice relaxation time T1, the linewidth parameter T*2the second moment of 1H NMR absorption, differential thermal analysis, and differential scanning calorimetry were performed on methylammonium tetrabromozincate(II) crystals from 58 to above 500 K. A solid-solid phase transition was located at 456 K. In the room temperature phase, 120° reorientational jumps of CH3 and NH3+ groups in the cation about its C -N bond axis were detected. In the high-temperature phase, the cations undergo overall reorientation as well as translational self-diffusion. The activation energy for the cationic self-diffusion was evaluated to be 18 kJ mol-1 .

Self-Diffusion and Reorientation of Methylammonium Ions in (CH3NH3)2ZnCl4 Crystals as Studied by 1H-NMR

1989 ◽  
Vol 44 (8) ◽  
pp. 741-746 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Tadashi Iwachido ◽  
Naomi Hayama ◽  
Ryuichi Ikeda ◽  
Mifune Terashima ◽  
...  
Keyword(s):  
Solid Phase ◽  
Relaxation Times ◽  
Three Dimensional ◽  
Lattice Relaxation ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Self Diffusion ◽  
H Nmr

Abstract Differential thermal analysis, differential scanning calorimetry, and measurements of the 1H spin-lattice relaxation times and second moments of 1H-NMR absorptions were performed on methylammonium tetrachlorozincate (II) crystals over a wide temperature range. A solid-solid phase transition was located at 477 K. From the 1H-NMR experiments it was found that the cations undergo overall reorientation as well as three dimensional translational self-diffusion in the high-temperature phase. In the low-temperature phase, a 120° reorientational motion of the CH3 and NH3+ groups of the cation about its C-N bond axis was detected. The parameters for the motional modes of the cations in the crystal were evaluated from the analysis of the 1H-NMR experimental results.

A Highly Disordered New Solid Phase Containing Isotropically Reorienting Cations in (CH3NH3 )2CdBr4 Studied by 1H NMR and Thermal Measurements

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1190-1192 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Kentaro Takagi ◽  
Mifune Terashima ◽  
Daiyu Nakamura
Keyword(s):  
Room Temperature ◽  
Solid Phase ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Spin Lattice ◽  
H Nmr ◽  
Thermal Measurements

Abstract The 1H spin-lattice relaxation time, linewidth, second moment of 1H NMR absorption, differen-tial thermal analysis, and differential scanning calorimetry of methylammonium tetrabromocado-mate(II) crystals were studied. A new solid phase was found between 482 K and the melting point (493 K). The 1H NMR measurements revealed the presence of overall reorientation of methyl-ammonium cations in this phase. In the room temperature phase, 120° reorientational jumps of the CH3 and NH3+ groups were detected.

H NMR Study of Ionic Motions in High Temperature Solid Phases of (CH3NH3)2ZnCl4

2000 ◽  
Vol 55 (3-4) ◽  
pp. 412-414 ◽  
Author(s):  
Hiroyuki Ishida
Keyword(s):  
Activation Energy ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
The Self ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Self Diffusion ◽  
Spin Lattice ◽  
H Nmr ◽  
Nmr Study

Abstract The reorientation of the tetrahedral complex anion ZnCl42- and the self-diffusion of the cation in (CH3NH3)2ZnCl4 were studied by 1H NMR spin-lattice relaxation time (1H T1) experiments. In the second highest-temperature phase, the temperature dependence of 1H T1 observed at 8.5 MHz could be explained by a magnetic dipolar-electric quadrupolar cross relaxation between 1H and chlorine nuclei, and the activation energy of the anion motion was determined to be 105 kJ mol -1 . In the highest-temperature phase, the activation energy of the self-diffusion of the cation was determined to be 58 kJ mol -1 from the temperature and frequency dependence of 1H T1

1H Nmr Study Of Molecular Motions In Thiourea Pyridinium Nitrate Inclusion Compound

2004 ◽  
Vol 59 (7-8) ◽  
pp. 505-509 ◽  
Author(s):  
M. Grottela ◽  
A. Kozak ◽  
A. Pajzderska ◽  
W. Szczepański ◽  
J. Wąsicki
Keyword(s):  
Inclusion Compound ◽  
Activation Parameters ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Spin Lattice ◽  
Nmr Study ◽  
Pyridinium Cations

The proton NMR second moment and spin-lattice relaxation time have been studied for polycrystalline thiourea pyridinium nitrate inclusion compound and its perdeuderated analogues in a wide temperature range. The reorientation of two dynamically different pyridinium cations around their pseudohexagonal symmetry axis taking place over inequivalent barriers have been revealed in the low-temperature phase. Activation parameters for these motions have been derived. A symmetrization of the potential barriers has been observed at the transition from intermediate to the high temperature phase. The motion of thiourea molecules has been also evidenced, but could not be unambiguously described.

Ionic Dynamics in Plastic Crystal KNO2 Studied by 39K and 15N NMR

1994 ◽  
Vol 49 (1-2) ◽  
pp. 247-252 ◽  
Author(s):  
Motoko Kenmotsu ◽  
Hisashi Honda ◽  
Hiroshi Ohki ◽  
Ryuichi Ikeda ◽  
Tomoki Erata ◽  
...  
Keyword(s):  
Intermediate Phase ◽  
Relaxation Times ◽  
Nmr Relaxation ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
15N Nmr ◽  
Temperature Phase ◽  
Self Diffusion ◽  
Spin Lattice

AbstractThe spin-lattice relaxation time of 39K NMR observed in the low-temperature phase (T<264.1 K) of KNO2 is explained by the quadrupole mechanism contributed from a newly found NO2- motion. The in-plane C3 reorientation and the overvall NO2 rotation as well as the self-diffusion were shown in the intermediate phase (T ≤ 314.7 K) and the high-temperature plastic phase (T < melting point: 710 K), respectively, by observing 39K and 15N NMR relaxation times and 15N lineshapes.

Structural Phase Transitions and Ionic Motions in Pyridinium Hexachlorotellurate(IV),Hexachlorostannate(IV), and Hexabromostannate(IV) Crystals as Studied by 1H NMR

1989 ◽  
Vol 44 (4) ◽  
pp. 300-306 ◽  
Author(s):  
Yutaka Tai ◽  
Tetsuo Asaji ◽  
Ryuichi Ikeda ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transitions ◽  
High Temperature ◽  
Structural Phase ◽  
Lattice Relaxation ◽  
Relaxation Mechanism ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Scanning Calorimetry ◽  
Spin Lattice ◽  
H Nmr

Abstract The 1H NMR second moment M2 and the spin-lattice relaxation time T1 are determined for pyridinium hexachlorotellurate(IV), hexachlorostannate(IV), and hexabromostannate(IV) at various temperatures above ca. 140 K. The phase transition temperatures already reported from halogen NQR experiments are determined as 272, 331, and 285 K, respectively, by differential thermal analysis (DTA). The DTA as well as differential scanning calorimetry measurements show that the above phase transitions are of second-order. For pyridinium hexachlorotellurate(IV) and hexa-bromostannate(I V), a sharp 1H T1 dip was observed at the transition temperature. This is interpreted in terms of a phenomenon related to the critical fluctuation of an order parameter. From the measurements of 1H M2, 60° two-site jumps (60° flips) around the pseudo C6 axis of the cation are suggested to occur in the high temperature phases of the complexes. Modulation of X...1H (X = CI, Br) magnetic dipolar interactions due to the reorientational motion of the complex anions is considered as a possible relaxation mechanism in the high temperature phases.

A Proton NMR Study of n-Decylammonium Chain Dynamics in the Perovskite-type Layered Compound (C10H21NH3)2CdCl4

1993 ◽  
Vol 48 (4) ◽  
pp. 563-569 ◽  
Author(s):  
Stefan Jurga ◽  
Kazimierz Jurga ◽  
Eduard C. Reynhardt ◽  
Piotr Katowski
Keyword(s):  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
High Temperature Phase ◽  
Spin Lattice Relaxation ◽  
Layered Compound ◽  
Temperature Phase ◽  
Potential Wells ◽  
Spin Lattice ◽  
Compound C ◽  
Nmr Study

Abstract A detailed proton second moment and spin-lattice relaxation time investigation of the bilayered compound (C10H21NH3)2 CdCl4 is reported. In the low temperature phase the methyl group exe-cutes a classical threefold reorientation, while the NH3 group is involved in a similar reorientation in an asymmetric potential well. Evidence for defect chain motions in this phase has been found, and infomation regarding the potential wells associated with these motions has been extracted from the data. In the high temperature phase, slow chain defect motions and fast fourfold reorientations of chains about their long axes, parallel to the normal to the bilayer, have been observed.

Thallium Nuclear Magnetic Relaxation in Solid Thallium (I) Thiocyanate TlSCN: Phase Transition and Ionic Motion

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1211-1216 ◽  
Author(s):  
Yoshihiro Furukawa ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transition ◽  
Orthorhombic Phase ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Scalar Coupling ◽  
Temperature Phase ◽  
Self Diffusion ◽  
Spin Lattice ◽  
Low Temperature Phase

Abstract The NMR spin-lattice relaxation time (T1) and linewidth parameter (T2*) of 203Tl and 205T1 in solid T1SCN were measured from 290 K up to the melting point (Tm = 507 K). The nonexponential magnetization recovery of could be characterized by a short (T1s) and a long (T11) component. T11 showed a T-2 dependence below ca. 350 K in the orthorhombic phase (T<Tc = 371 K) and a minimum in the tetragonal phase (Tc<T<Tm), which were interpreted in terms of lattice vibrations and head-to-tail flips of the linear SCN- ions, respectively. A broad minimum of 77 around 360 K was explained in terms of indirect nucleus-electron scalar coupling between 203Tl and 205Tl, modulated via the anionic flips occurring in the symmetric and asymmetric potential fields for the highland low-temperature phase, respectively. The phase transition is closely related to dynamical disorder of the anionic orientations. At higher temperatures, translational self-diffusion of Tl+ was evidenced by the T2* and T1s results

Phase transitions and molecular motions in adamantane derivatives: 1-adamantanol

1987 ◽  
Vol 65 (8) ◽  
pp. 1757-1760 ◽  
Author(s):  
Pierre D. Harvey ◽  
Denis F. R. Gilson ◽  
Ian S. Butler
Keyword(s):  
High Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
High Temperature Phase ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Adamantane Derivatives ◽  
Hydroxyl Groups ◽  
Temperature Phase ◽  
Spin Lattice

An order–disorder transition occurs in 1-adamantanol at 359 K on heating and at 342 K on cooling, with transition entropies of 36 and 34 J K−1 mol−1, respectively. FT-ir spectra show that free hydroxyl groups exist in the high temperature phase, but the majority of the O—H groups remain hydrogen bonded. The barrier to adamantyl group rotation in the low-temperature phase, determined from proton spin–lattice relaxation time measurements, is 20.9 Kj mol−1, and the barrier to rotation in the high-temperature phase is 35.0 kJ mol−1.

scholarly journals 1H NMR and Differential Scanning Calorimetry Studies of Molecular Motion and Phase Transition in Butylammonium Iodide

1985 ◽  
Vol 40 (4) ◽  
pp. 347-354
Author(s):  
Shin-ichi Fukada ◽  
Ryuichi Ikeda ◽  
Daiyu Nakamura
Keyword(s):  
Phase Transition ◽  
Low Temperature ◽  
Solid Phase ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
H Nmr ◽  
Wide Range

The temperature variations of 1H NMR spin-lattice relaxation times and 1H NMR second moments in n-C4H9NH3I and its N-deuterated analog were studied in a wide range of temperatures above 77 K. DTA experiments revealed a solid-solid phase transition between room and low temperature phases taking place at 268 K for the former salt and at 267 K for the latter. For rapidly cooled ( ≳ 2 Kmin-1 ) samples, another phase transition possibly between substable low temperature phases was found at ca. 210 K for the former and ca. 205 K for the latter. The transition entropy observed at 268 K was 33 J K-1 mol-1. This is much larger than the melting entropy (16 J K-1 mol-1), suggesting that butylammonium ions obtain their motional freedom mostly at the phase transition. In the low temperature phase of n-C4H9NH3I, the CH3 and NH3+ groups perform C3 reorientation about their respective symmetry axes with the activation energies 10.4 and 26.8kJmol-1, respectively. The rapidly cooled sample showed two T1 components attributable to the stable and substable low temperature phases indicating the coexistence of both phases. In the room temperature phase, the cations rotate rapidly about their long axes and partly conformational disorder of the alkyl chains takes place. The mechanism of the phase transitions is discussed.

Sign in / Sign up

Export Citation Format

Share Document