Samarium sulfide doped with various rare earth elements shrinks as the temperature increases from about minus 175°C to about 40-60°C. Shown here is the relative linear shrinkage compared to the length at about 120°C. For the Cerium (Ce) dopant, the percentage volume decrease is about 2.6%. These samples were produced by an industrially scalable process, paving the way for practical applications of this class of sulfides as thermal-expansion compensators.