File Name : fig s1.tiff

Caption : fig. s1 the construction scheme of the supercells, as well as the tested models.

File Name : fig s2.tiff

Caption : fig. s2 free energy in mev as a function of temperature in k° associated with the formation of the new phase according to the reaction:
srsno₃ + sr₂sbino₆ → 3/2 sr₂(sn₀.₃₃sb₀.₃₃in₀.₃₃)₂o6



File Name : fig s3.tiff

Caption : fig. s3 williamson-hall (w-h) plot of sr2(sn0.33sb0.33in0.33)2o6.

File Name : fig s4.tiff

Caption : fig. s4 experimental ir spectrum of the sr2(sn0.33sb0.33in0.33)2o6 within the 
range of 400 to 2000 cm⁻¹.


File Name : fig s5.tiff

Caption : fig. s5: calculated raman spectrum of the most stable o9 model (model 8) compared to the o6 model (model 1). schematics of the vibrational modes associated with the most intense stretches are shown in (a) and (b). the region above 700 cm⁻¹ is dominated by in–o and sn–o bond stretching, while the region between 650–700 cm⁻¹ primarily corresponds to the stretching of oxygen atoms bonded to sb and sn.