The long-range structure of the samples was characterized by simultaneous Rietveld refinement of x-ray (Figure ) and neutron (Figure ) powder diffraction data (also see supporting information Figure ). The materials crystallized in the monoclinic space group 𝐶2/𝑚 (12), consistent with previous work . The structure is based on cubic-close-packing of Cl anions. The cations occupy mostly octahedral sites and are arranged in layers (Figure ). One layer is occupied by Li (between B and C), followed by a mixed cation Li/In/Zr layer (between layers A and C, A and B). The lattice parameter a showed a small increase (6.404-6.416 Å) with increasing Zr-dopant concentration, while c decreased (6.380-6.357 Å), which is consistent with literature (SI Figure ). The angle beta showed only a slight increase (109.776 -109.961°) while the lattice volume showed a maximum at x=0.2, but with small absolute changes (within 1.5 Å 3 ) (SI Figure ). For compositions with x=0 and 0.2 we find the occupation of a tetrahedral site in the mixed cation layer (Li3 in Figure top image, in the M-layer). The occupancy of this site can be visualized from the effective neutron scattering-length-density map shown in Figure . An effective scattering length density map is the Fourier transform of the diffracted signal, combining the intensity information from the measurement and the phase information from the model. This is the neutron-equivalent of the electron density maps from x-ray diffraction data.