𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Phase Transitions in KNO3 Studied by Variable-Temperature 15N Magic-Angle Spinning NMR Spectroscopy

✍ Scribed by Bjarke V. Schønwandt; Hans J. Jakobsen

Publisher
Elsevier Science
Year
1999
Tongue
English
Weight
121 KB
Volume
145
Category
Article
ISSN
0022-4596

No coin nor oath required. For personal study only.

✦ Synopsis

The phase transitions within the three phases of potassium nitrate ( -, -, and -KNO 3 ) have been investigated in detail by variable-temperature (VT) 15 N magic-angle spinning (MAS) NMR spectroscopy employing 98% 15 N-enriched KNO 3 . The stability of the metastable -KNO 3 phase is found to be highly in6uenced by the thermal history of the sample, i.e., by the number of heating cycles into the high-temperature -KNO 3 phase at 1603 C. Furthermore, the spectral appearance for the room-temperature -KNO 3 phase is found to change after excursions of the sample into the high-temperature -KNO 3 phase, an observation similar to that made in a recent VT synchrotron X-ray powder di4raction study.

📜 SIMILAR VOLUMES

Combined variable-temperature and variab
Combined variable-temperature and variable-field 15N cross-polarization magic angle spinning NMR study of 15N,14N residual dipolar coupling in pyrazole derivatives
✍ Sergio H. Alarcón; José A. Jiménez; Rosa M. Claramunt; Hans-Heinrich Limbach; Jo 📂 Article 📅 2000 🏛 John Wiley and Sons 🌐 English ⚖ 88 KB

A study of the residual dipolar 15 N, 14 N coupling observed in 15 N cross-polarization magic angle spinning NMR spectra at variable temperature and variable field in 1-amino-and 1-nitropyrazole is reported. Residual dipolar 15 N, 14 N coupling is present in high-resolution 15 N spectra as an asymme

Dynamics of ferrocene molecules enclathr
Dynamics of ferrocene molecules enclathrated in β-cyclodextrin as studied by variable-temperature one-dimensional SASS (switching-angle sample spinning) NMR spectroscopy
✍ Daisuke Kuwahara; Fumio Imashiro; Takehiko Terao 📂 Article 📅 1993 🏛 Elsevier Science 🌐 English ⚖ 369 KB

The four guest ferrocene molecules in the unit cell of the j3-cyclodextrin/ferrocene inclusion compound crystal were found to have three different configurations among the five possible sites and exchange among the three; the enthalpy (m) and entropy (ds) differences between two degenerate configura

A variable-temperature 13C cross-polariz
A variable-temperature 13C cross-polarization magic angle spinning NMR study of some unusual dynamic and phase properties of (±)-3,4-di-O-acetyl-1,2,5,6-tetra-O-benzyl-myo-inositol, ‘jumping crystals’
✍ Jamila Fattah; J. Mark Twyman; Christopher M. Dobson 📂 Article 📅 1992 🏛 John Wiley and Sons 🌐 English ⚖ 598 KB

## Abstract Variable‐temperature ^13^C CP/MAS NMR experiments were carried out on crystalline (±)‐3,4‐di‐__O__‐acetyl‐1,2,5,6‐tetra‐__O__‐benzyl‐__myo__‐inositol. Three distinct phases can be distinguished from their NMR characteristics, each stable over a well defined temperature range, in accord