Samarium monochalcogenides are chemical compounds with the composition SmX, where Sm stands for the lanthanide element samarium and X denotes any one of three chalcogen elements, sulfur, selenium or tellurium, resulting in the compounds SmS, SmSe or SmTe.
Single crystals or polycrystals of samarium monochalcogenides can be obtained by reacting the metal with sulfur, selenium or tellurium vapors at high temperature.
[4] This results in spectacular change in color from black to golden yellow when scratching or mechanically polishing SmS.
Their metallic behavior results from the decreasing band gap, which amounts at zero pressure to 0.15, 0.45 and 0.65 eV in SmS, SmSe and SmTe, respectively.
[9] Samarium monosulfide also generates electric voltage upon moderate heating to about 150 °C that can be applied in thermoelectric power converters.