CATIONIC MOTIONS INVOLVING SELF-DIFFUSION AND STRUCTURAL PHASE TRANSITIONS IN SOLID DIMETHYL- AND TRIMETHYLAMMONIUM NITRATES AS STUDIED BY DIFFERENTIAL THERMAL ANALYSIS AND ¹H NMR TECHNIQUES.

Differential thermal analysis and the temperature dependence of broad-line **1H NMR absorptions and of **1H spin-lattice relaxation times in both laboratory and rotating frames were observed for (CH//3)//2NH//2NO//3, (CH//3)//2ND//2NO//3, and (CH//3)//3NHNO//3. A solid-solid phase transition was located at 297 K for (CH//3)//2NH//2NO//3, while two phase transitions at 359 and 407 K were found for (CH//3)//3NHNO//3. The **1H spin-lattice relaxation times in the laboratory frame at different Larmor frequencies and those in the rotating frame at the rf field of 8 G observed for the above salts were analyzed by referring to the **1H NMR second moments determined. The motional parameters of the cations in each solid phase of the salts were evaluated by a fitting calculation to the relaxation times observed.