Direct measurement of the magnetocaloric effect on La(Fe_(13-x-y)Co_y)Si_x compounds near room temperature

摘要

The magnetic and magnetocaloric properties of LaFe_(11.9-y)Co_ySi_(1.1) compounds with y=0.8 and 0.9 have been investigated. The temperature dependence of magnetization data revealed that LaFe_(11.1)Co_(0.8)Si_(1.1) and LaFe_(11)Co_(0.9)Si_(1.1) exhibit a second-order magnetic transition near room temperature at 282 and 294 K, respectively. Under a magnetic field change of 5 T, the maximum values of isothermal entropy change -△S are found to be 15 and 13.5 J/kg K for y=0.8 and 0.9, respectively. The refrigerant capacity has been calculated to be 320 J/kg for y=0.8 and 266 J/kg for y=0.9 under a field change of 5 T. Direct measurements of the temperature change for LaFe_(11.9-y)CO_ySi_(1.1) compounds around room temperature were also performed. Measurements of ΔT were performed in adiabatic conditions with practice-oriented method by using a specially developed test bench. For both materials, the normalized temperature change was found to be about 1 K/T at their Curie temperatures.