scholarly journals 1H nuclear magnetic resonance spin-lattice relaxation, 13C magic-angle-spinning nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and x-ray diffraction of two polymorphs of 2,6-di-tert-butylnaphthalene

2000 ◽  
Vol 113 (5) ◽  
pp. 1958-1965 ◽  
Author(s):  
Peter A. Beckmann ◽  
Kendra S. Burbank ◽  
Katharine M. Clemo ◽  
Erin N. Slonaker ◽  
Kristin Averill ◽  
...  

2015 ◽  
Vol 70 (4) ◽  
pp. 295-300 ◽  
Author(s):  
Mateusz Paczwa ◽  
Aleksej A. Sapiga ◽  
Marcin Olszewski ◽  
Nikolaj Sergeev ◽  
Aleksej V. Sapiga

AbstractThe temperature dependences of nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR spectra of 23Na nuclei in natrolite (Na2Al2Si3O10·2H2O) have been studied. The temperature dependences of the spin-lattice relaxation times T1 in natrolite have also been studied. It has been shown that the spin-lattice relaxation of the 23Na is governed by the electric quadrupole interaction with the crystal electric field gradients modulated by translational motion of H2O molecules in the natrolite pores. The dipolar interactions with paramagnetic impurities become significant as a relaxation mechanism of the 23Na nuclei only at low temperature (<270 K).



Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2895 ◽  
Author(s):  
Ae Ran Lim ◽  
Sun Ha Kim

The thermal properties of organic–inorganic (CH3NH3)2CoBr4 crystals were investigated using differential scanning calorimetry and thermogravimetric analysis. The phase transition and partial decomposition temperatures were observed at 460 K and 572 K. Nuclear magnetic resonance (NMR) chemical shifts depend on the local field at the site of the resonating nucleus. In addition, temperature-dependent spin–lattice relaxation times (T1ρ) were measured using 1H and 13C magic angle spinning NMR to elucidate the paramagnetic interactions of the (CH3NH3)+ cations. The shortening of 1H and 13C T1ρ of the (CH3NH3)2CoBr4 crystals are due to the paramagnetic Co2+ effect. Moreover, the physical properties of (CH3NH3)2CoBr4 with paramagnetic ions and those of (CH3NH3)2CdBr4 without paramagnetic ions are reported and compared.



2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ae Ran Lim ◽  
Sun Ha Kim ◽  
Yong Lak Joo

AbstractThe physical properties of the organic–inorganic hybrid crystals having the formula [NH3(CH2)3NH3]ZnX4 (X = Cl, Br) were investigated. The phase transition temperatures (TC; 268K for Cl and 272K for Br) of the two crystals bearing different halogen atoms in their skeletons were determined through differential scanning calorimetry. The thermodynamic properties of the two crystals were investigated through thermogravimetric analysis. The structural dynamics, particularly the role of the [NH3(CH2)3NH3] cation, were probed through 1H and 13C magic-angle spinning nuclear magnetic resonance spectroscopy as a function of temperature. The 1H and 13C NMR chemical shifts did not show any changes near TC. In addition, the 1H spin–lattice relaxation time (T1ρ) varied with temperature, whereas the 13C T1ρ values remained nearly constant at different temperatures. The T1ρ values of the atoms in [NH3(CH2)3NH3]ZnCl4 were higher than those in [NH3(CH2)3NH3]ZnBr4. The observed differences in the structural dynamics obtained from the chemical shifts and T1ρ values of the two compounds can be attributed to the differences in the bond lengths and halogen atoms. These findings can provide important insights or potential applications of these crystals.



2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Edda Winter ◽  
Philipp Seipel ◽  
Tatiana Zinkevich ◽  
Sylvio Indris ◽  
Bambar Davaasuren ◽  
...  

Abstract Various nuclear magnetic resonance (NMR) methods are combined to study the structure and dynamics of Li1.5Al0.5Ti1.5(PO4)3 (LATP) samples, which were obtained from sintering at various temperatures between 650 and 900 °C. 6Li, 27Al, and 31P magic angle spinning (MAS) NMR spectra show that LATP crystallites are better defined for higher calcination temperatures. Analysis of 7Li spin-lattice relaxation and line-shape changes indicates the existence of two species of lithium ions with clearly distinguishable jump dynamics, which can be attributed to crystalline and amorphous sample regions, respectively. An increase of the sintering temperature leads to higher fractions of the fast lithium species with respect to the slow one, but hardly affects the jump dynamics in either of the phases. Specifically, the fast and slow lithium ions show jumps in the nanoseconds regime near 300 and 700 K, respectively. The activation energy of the hopping motion in the LATP crystallites amounts to ca. 0.26 eV. 7Li field-gradient diffusometry reveals that the long-range ion migration is limited by the sample regions featuring slow transport. The high spatial resolution available from the high static field gradients of our setup allows the observation of the lithium ion diffusion inside the small (<100 nm) LATP crystallites, yielding a high self-diffusion coefficient of D = 2 × 10−12 m2/s at room temperature.



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