Phase compositions and crystal structures of Gd6X2Si3 (X = Ni, Co) and Ln6Co2Si3 (Ln = Pr, La) have been studied. The magnetic properties of Gd6X2Si3 (X = Ni, Co) and Ln6Co2Si3 (Ln = Pr, La) have been evaluated from magnetization measurements performed by a superconducting quantum interference device magnetometer in a temperature interval of 5–400 K, and at magnetic fields up to 5 T. The crystal structures of Gd6X2Si3 (X = Co, Ni) and Ln6Co2Si3 (Ln = Pr, La) were found to be hexagonal at 300 K. The Curie temperature (TC), effective and magnetic moment of the compounds (at 5 K) have been determined for Gd6X2Si3 (X = Ni, Co), and Ln6Co2Si3 (Ln = Pr, La). TC was found to depend on composition, and reaches maximum value of about 300 K for the Gd6X2Si3 system. The magnetocaloric effect (magnetic entropy changes and relative cooling power (RCP) was found to depend on X and Ln, and the maximum RCP values were found to be larger than 500 J/kg near room temperature for the Gd6Ni2Si3 and Gd6Co2Si3 compounds. This value of RCP is comparable to the prototype magnetic refrigeration material, Gd.
Pathak, Arjun K., Dubenko, Igor, Stadler, Shane and Ali, Naushad. "Magnetic and Magnetocaloric Properties of Gd6X2Si3 (X = Ni, Co) and Ln6Co2Si3 (Ln = Pr, La)." (Apr 2011).