We designed a novel molten salt sample holder, shown in Fig. , for X-ray di↵raction. This design combines the high-temperature stability and relative ease of sealing quartz with the excellent corrosion resistance of graphite. Sealed NMR capillaries (Wilmad-LabGlass, 3 mm diameter quartz tube) prevent the exposure of molten salt to air while minimizing the background signal from X-ray scattering by quartz. (The capillary is sealed under rough vacuum.) The graphite insert contains the salt while preventing corrosion damage to the quartz from molten salt at high temperatures. In addition, the graphite insert can be used to monitor accurately the temperature of the molten salt, as described below. High-energy X-rays used for total di↵raction measurements penetrate the graphite rod with very little loss. However, this design has been used for low-energy X-rays as well. The salt does not wet graphite, and so the meniscus that forms in the liquid can protrude above the graphite edge.