Studies on magnetocaloric effect of Tb2Ni0.90Si2.94compound.

A comparative study has been carried out on the magnetocaloric properties of as-cast and annealed Tb2Ni0.90Si2.94intermetallic compound. While the as-cast form exhibits ferromagnetic cluster-glass behaviour below 9.9 K coexisting with antiferromagnetic (AFM) interaction, the annealed system shows AFM ordering below 13.5 K and spin freezing occurs below 4 K. The compound exhibits moderate magnetocaloric performance with maximum isothermal entropy changes (-ΔSM) 8.8 and 10.9 J/kg-K, relative cooling power (RCP) 306 and 365 J/kg, along with adiabatic temperature change (ΔTad) 5.5 and 8.15 K for 70 kOe magnetic field change in as-cast and annealed forms, respectively. The estimated magnetic entropy change is found to be larger for annealed sample in comparison to that of as-cast analogue. However, the FWHM of -ΔSM(T) behaviour is larger in as-cast compound due to the presence of inherent structural disorder which reduces with thermal annealing. A positive isothermal entropy change (-ΔSM) and adiabatic temperature change (ΔTad) is observed for the as-cast compound in the measured field and temperature region. In contrast, the annealed system exhibits inverse magnetocaloric effect in the low field and temperature region where AFM interactions dominate. Magnetocaloric effect (MCE) is used as a tool to establish a subtle correlation between the observed magnetocaloric effect and the reported magnetic properties of the system.