Giant low-field magnetocaloric effect in EuTi_1-xNb_xO₃ (x=0.05, 0.1, 0.15, and 0.2) compounds

The magnetic properties and magnetocaloric effect (MCE) of EuTi_1-xNb_xO₃ (x=0.05, 0.1, 0.15, and 0.2) compounds are investigated. Owing to electronic doping, parts of Ti ions are replaced by Nb ions, the lattice constant increases and a small number of Ti⁴⁺ (3d⁰) ions change into Ti³⁺ (3d¹). It is the ferromagnetism state that is dominant in the derivative balance. The values of the maximum magnetic entropy change (-ΔS_M^max) are 10.3 J/kg·K, 9.6 J/kg·K, 13.1 J/kg·K, and 11.9 J/kg·K for EuTi_1-xNb_xO₃ (x=0.05, 0.1, 0.15, and 0.2) compounds and the values of refrigeration capacity are 36, 33, 86, and 80 J/kg as magnetic field changes in a range of 0 T-1 T. The EuTi_1-xNb_xO₃ (x=0.05, 0.1, 0.15, and 0.2) compounds with giant reversible MCE are considered as a good candidate for magnetic refrigerant working at low-temperature and low-field.