Magnetocaloric effect in the vicinity of the magnetic phase transition in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>NdCo</mml:mi><mml:mrow><mml:mn>2</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Fe</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math> compounds
Adil Murtaza, Wenliang Zuo, Muhammad Yaseen, Awais Ghani, Azhar Saeed, Chunxi Hao, Jingwen Mi, Yebei Li, Tieyan Chang, Liqun Wang, Chao Zhou, Yu Wang, Yin Zhang, Sen Yang, Yang Ren
Abstract
In the present paper, the magnetocaloric effect (MCE) of ${\mathrm{NdCo}}_{2\ensuremath{-}x}{\mathrm{Fe}}_{x}$ ($x\phantom{\rule{0.28em}{0ex}}=\phantom{\rule{0.28em}{0ex}}0$, 0.2, 0.4, 0.6) compounds was investigated by magnetization measurements. The temperature-dependent high-resolution synchrotron x-ray diffraction study shows a magnetostructural transition from the paramagnetic cubic phase to the ferromagnetic tetragonal phase below their Curie temperatures. Differential scanning calorimetry analysis shows the absence of thermal hysteresis, indicating the second-order nature of the magnetostructural phase transition in these compounds. The maximum values of magnetic entropy change ($\mathrm{\ensuremath{\Delta}}{S}_{M}$) and wide operating temperature (OT) are obtained under a field change of 5 T, which are 7.33 ${\mathrm{Jkg}}^{\ensuremath{-}1}{\mathrm{K}}^{\ensuremath{-}1}$, 6.45 ${\mathrm{Jkg}}^{\ensuremath{-}1}{\mathrm{K}}^{\ensuremath{-}1}$, 5.71 ${\mathrm{Jkg}}^{\ensuremath{-}1}{\mathrm{K}}^{\ensuremath{-}1}$, 4.70 ${\mathrm{Jkg}}^{\ensuremath{-}1}{\mathrm{K}}^{\ensuremath{-}1}$ and 78 K, 82 K, 85 K, 92 K for $x$ = 0, 0.2, 0.4, and 0.6, respectively. The corresponding values of relative cooling power (RCP) are 529.96 ${\mathrm{Jkg}}^{\ensuremath{-}1}$, 497.25 ${\mathrm{Jkg}}^{\ensuremath{-}1}$, 470.55 ${\mathrm{Jkg}}^{\ensuremath{-}1}$, and 428.31 ${\mathrm{Jkg}}^{\ensuremath{-}1}$. The observed wide OT range and large RCP values are comparable with Gd, ${\mathrm{Gd}}_{5}{\mathrm{Ge}}_{2}{\mathrm{Si}}_{2}$, and some rare-earth-based giant magnetocaloric materials, making this series of compounds suitable for magnetic refrigeration.