Electron channeling studies of atom site preference and distribution in doped Mg2Si1-xSnx thermoelectrics

•Direct evidence of atom distribution in magnesium silicide thermoelectrics by electron channeling.•Bi occupies empty N and C octahedral sites, with a tendency to substitute for Sn.•Bi and Sn exhibit more uneven distribution compared to Si.•Mg and potential vacancies occupy both T tetrahedral sites.•Host and dopant ions’ distribution are in line with thermoelectric properties.