The diffraction analysis shows that crystalline, single-phase materials are formed through mechanochemical means across the compositional range, with the exception of Li3Sb0.50Bi0.50, which showed clear signs of phase separation that could not be entirely eliminated by annealing (see Figure ). Though the diffraction method is an excellent tool to assess the average longrange structure of crystalline solids, it is insensitive to short-range variations in composition and/or lattice spacings, reported for several metal-hydrogen systems. Furthermore, light elements such as lithium are harder to detect accurately using XRD because of their low number of electrons. However, NMR spectroscopy is sensitive to both structure (short and medium range) and dynamics in Li-containing materials; therefore, we used NMR spectroscopy to probe both the local chemical structure of Sb/Bi mixing and Li-ion dynamics in these Li3SbxBi1-x ternary alloys. Lithium-7 (I=3/2) is an attractive nucleus for NMR spectroscopy due to its high receptivity (92.4% N.A. and = 38.9%) and extremely small quadrupole moment (Q = -4.01 fm 2 ). These physical properties for Li result in it behaving as a pseudo-nuclear spin-½ NMR nucleus, contributing insignificantly to second-order quadrupolar broadening of the central transition peak. Figure (a) shows the Li MAS NMR spectra for the binary Li3Sb and Li3Bi as well as the intermediate Li3SbxBi1 compositions. Li3Bi and Li3Sb have isotropic chemical shifts of 10.5 ppm and 7.3 ppm, respec i el , and can be fi sing a single Ga ssian, or for Li3Bi, Lorentzian peak. Both compounds adopt a cubic crystal structure (Fm3 m) as per Figure , as expected based on available literature data. The linewidths for Li NMR spectra are typically influenced by either a strong Li- Li homonuclear dipolar coupling, local structural disorder about the Li, or a combination of these. The relatively sharp Li3Bi resonance (fwhm = 40 Hz or 0.2 ppm) measured under MAS at room temperature has a Lorentzian-like lineshape supporting fast Li-ion mobility at room temperature. Li3Sb reveals a broader Gaussian-like resonance (fwhm = 340 Hz, 1.8 ppm), which is likely associated with a higher distribution of local chemical environments that results from the mechanochemical treatment (vs. annealing performed on the Li3Bi materials). This observation is consistent with the lower crystallinity identified from the XRD data that contributes to broadening (due to distribution in chemical shift) in the Li NMR spec r m. A lo in ensi si e obser ed in he spec r m a 19 ppm (f hm = 740 H ) indica ed by the cross, is attributed to Li2Sb (hexagonal structure) as a trace impurity. Three unique compositional mixtures, Li3SbxBi1-x, where x = 0.25, 0.5 and 0.75, reveal Li Gaussian-like resonances that are broader (fwhm = 400 -500 Hz) and isotropic chemical shifts located between those for the parent endmembers. These results are consistent with Sb being incorporated into the lattice across the series and are summarized in Table and Figure .