The remarkable impact of nitridation temperature on the magnetocaloric effect of CoFe2/MgO matrix

Abstract

In this study, a phenomenological model is used to predict the magnetocaloric effect (MCE) of two CoFe₂/MgO nanocomposite samples exposed to nitridation reactions at nitridation temperatures of 400 and 500 °C (they are indicated as N400 and N500, respectively). The findings show that, within the investigated temperature range, the MCE of the N400 sample is conventional with full-width at half-maximum (\(\delta {\text{T}}_{{{\text{FWHM}}}}\)) of 94 K. The N500 sample does, however, actually contain both inverse and conventional MCE with \(\delta {\text{T}}_{{{\text{FWHM}}}}\) of 71 K and 24 K, respectively. Interestingly, the changing nitridation temperature during sample preparation allows for significant tailoring of the MCE of a CoFe2/MgO nanocomposite sample. The MCE of the N400 and N500 samples, in particular, spans a wide range of temperatures, including room temperature and cryogenic temperatures, making them notable magnetocaloric materials. Consequently, N400 and N500 samples can be used food-refrigeration and liquefying both nitrogen and helium gases.