Fig. 1. Illustration of the laser heating method used in HT-NMR spectroscopy

Fig. 2. Design drawing of the inner tube of the proposed high-temperature sample cell

Fig. 3. Photos of the complete inner Al₂O₃ and AlN tubes (a), outer ZrO₂ tubes (b), and assembled sample container (c)

Fig. 4. (a) ⁷⁹Br NMR spectra of the KBr at different laser power, (b) Fitting curve of laser power and temperature

Fig. 5. Temperature fitting curve and average curve of laser power in three experiments using sample container composed of an outer ZrO₂ tube and inner AlN tube

Fig. 6. Temperature fitting curve and average curve of laser power using sample container composed of an outer ZrO₂ tube and inner BN tube (a) and Al₂O₃ (b) tube

Fig. 7. ³⁵Cl HT-NMR spectra of the LiCl-KCl molten salt in the temperature range of 25 ℃ to 469 ℃