Journal of Superconductivity and Novel Magnetism, 2020
A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni50Mn... more A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni50Mn30Sn20 (Sn20) and Ni50Mn30In20 (In20) alloys has been investigated by means of Xrays diffraction and magnetic measurements. Ni50Mn30Sn20 alloy shows a cubic austenite 2 1 structure, and undergoes a second order magnetic transition at a Curie temperature of ,1 (20) = 333. However, the Ni50Mn30In20 alloy exhibits a mixture of cubic 2 1 and 2 austenite structures having Curie temperatures of ,2 (20) = 285 and * (20) = 330 , respectively. The modified Arrott plots, Kouvel-Fisher curves and critical isotherm analysis have been used to estimate the critical exponents (, , and ) around the Curie temperature. For Sn20 alloy, the reliable exponents are consistent with the mean field model, revealing long-range ferromagnetic interactions. Nevertheless, the critical exponents of In20 alloy around 330 K cannot be arranged into any of the universality classes of well-known classical standard models. The maximum entropy change under 5 T of Sn20 (∆ = 2.43 .) is slightly higher than that of In20 (∆ = 2.05 .). The experimental results of entropy changes are in good agreement with those calculated using Landau theory.
Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribb... more Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribbons have been examined by means of scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and magnetic measurements. The melt spun ribbons exhibit a single phase cubic L2 1 austenite structure at room temperature with a space group FmÀ3m, and lattice parameter a ¼ 5.956 Å. The DSC results reveal the first order reverse and forward martensitic transition (M s ¼ 147.4 K, M f ¼ 133.7 K, A s ¼ 155 K and A f ¼ 171 K) with a thermal hysteresis of about 21.3 K around the martensitic transition between heating and cooling. The thermomagnetic measurements show that the melt spun ribbons undergo a second order magnetic transition at a Curie temperature T C ¼ 310 K and a first order martensitic transition at T M ¼ 160 K. The critical behavior associated with the magnetic phase transition has been investigated through the isothermal magnetization measurements around T C. The critical exponents have been estimated by several methods such as the modified Arrott plots, Kouvel-Fisher method and critical isothermal analysis. The critical exponents values b ¼ 0:456, g ¼ 0:88 and d ¼ 2:929 are close to those predicted from the mean field model revealing a dominated long-range order of magnetic interactions. For an applied magnetic field of 5 T, the maximum magnetic entropy change ðDS Mmax Þ and the relative cooling power (RCP) values around T C are of about 2.105 J/kg.K and 132.5 J/kg, respectively. The melt-spun Ni 50 Mn 35 Sn 15 alloy is a good candidate for magnetic refrigeration near room temperature.
A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni 50 ... more A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni 50 Mn 30 Sn 20 (Sn20) and Ni 50 Mn 30 In 20 (In20) alloys has been investigated by means of X-ray diffraction and magnetic measurements. Ni 50 Mn 30 Sn 20 alloy shows a cubic austenite L2 1 structure and undergoes a second order magnetic transition at a Curie temperature of T A c;1 Sn20 ð Þ¼333 K. However, the Ni 50 Mn 30 In 20 alloy exhibits a mixture of cubic L2 1 and B2 austenite structures having Curie temperatures of T A c;2 In20 ð Þ¼ 285 K and T * c In20 ð Þ¼ 330 K, respectively. The modified Arrott plots, Kouvel-Fisher curves and critical isotherm analysis have been used to estimate the critical exponents (β, γ and δ) around the Curie temperature. For Sn 20 alloy, the reliable exponents are consistent with the mean field model, revealing long-range ferromagnetic interactions. Nevertheless, the critical exponents of In 20 alloy around 330 K cannot be arranged into any of the universality classes of well-known classical standard models. The maximum entropy change under 5 T of Sn20 (ΔS max M ¼ 2:43 J kg :K) is slightly higher than that of In20 (ΔS max M ¼ 2:05 J kg :K). The experimental results of entropy changes are in good agreement with those calculated using Landau theory.
Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribb... more Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribbons have been examined by means of scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and magnetic measurements. The melt spun ribbons exhibit a single phase cubic L2 1 austenite structure at room temperature with a space group FmÀ3m, and lattice parameter a ¼ 5.956 Å. The DSC results reveal the first order reverse and forward martensitic transition (M s ¼ 147.4 K, M f ¼ 133.7 K, A s ¼ 155 K and A f ¼ 171 K) with a thermal hysteresis of about 21.3 K around the martensitic transition between heating and cooling. The thermomagnetic measurements show that the melt spun ribbons undergo a second order magnetic transition at a Curie temperature T C ¼ 310 K and a first order martensitic transition at T M ¼ 160 K. The critical behavior associated with the magnetic phase transition has been investigated through the isothermal magnetization measurements around T C. The critical exponents have been estimated by several methods such as the modified Arrott plots, Kouvel-Fisher method and critical isothermal analysis. The critical exponents values b ¼ 0:456, g ¼ 0:88 and d ¼ 2:929 are close to those predicted from the mean field model revealing a dominated long-range order of magnetic interactions. For an applied magnetic field of 5 T, the maximum magnetic entropy change ðDS Mmax Þ and the relative cooling power (RCP) values around T C are of about 2.105 J/kg.K and 132.5 J/kg, respectively. The melt-spun Ni 50 Mn 35 Sn 15 alloy is a good candidate for magnetic refrigeration near room temperature.
Journal of Superconductivity and Novel Magnetism, 2020
A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni50Mn... more A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni50Mn30Sn20 (Sn20) and Ni50Mn30In20 (In20) alloys has been investigated by means of Xrays diffraction and magnetic measurements. Ni50Mn30Sn20 alloy shows a cubic austenite 2 1 structure, and undergoes a second order magnetic transition at a Curie temperature of ,1 (20) = 333. However, the Ni50Mn30In20 alloy exhibits a mixture of cubic 2 1 and 2 austenite structures having Curie temperatures of ,2 (20) = 285 and * (20) = 330 , respectively. The modified Arrott plots, Kouvel-Fisher curves and critical isotherm analysis have been used to estimate the critical exponents (, , and ) around the Curie temperature. For Sn20 alloy, the reliable exponents are consistent with the mean field model, revealing long-range ferromagnetic interactions. Nevertheless, the critical exponents of In20 alloy around 330 K cannot be arranged into any of the universality classes of well-known classical standard models. The maximum entropy change under 5 T of Sn20 (∆ = 2.43 .) is slightly higher than that of In20 (∆ = 2.05 .). The experimental results of entropy changes are in good agreement with those calculated using Landau theory.
Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribb... more Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribbons have been examined by means of scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and magnetic measurements. The melt spun ribbons exhibit a single phase cubic L2 1 austenite structure at room temperature with a space group FmÀ3m, and lattice parameter a ¼ 5.956 Å. The DSC results reveal the first order reverse and forward martensitic transition (M s ¼ 147.4 K, M f ¼ 133.7 K, A s ¼ 155 K and A f ¼ 171 K) with a thermal hysteresis of about 21.3 K around the martensitic transition between heating and cooling. The thermomagnetic measurements show that the melt spun ribbons undergo a second order magnetic transition at a Curie temperature T C ¼ 310 K and a first order martensitic transition at T M ¼ 160 K. The critical behavior associated with the magnetic phase transition has been investigated through the isothermal magnetization measurements around T C. The critical exponents have been estimated by several methods such as the modified Arrott plots, Kouvel-Fisher method and critical isothermal analysis. The critical exponents values b ¼ 0:456, g ¼ 0:88 and d ¼ 2:929 are close to those predicted from the mean field model revealing a dominated long-range order of magnetic interactions. For an applied magnetic field of 5 T, the maximum magnetic entropy change ðDS Mmax Þ and the relative cooling power (RCP) values around T C are of about 2.105 J/kg.K and 132.5 J/kg, respectively. The melt-spun Ni 50 Mn 35 Sn 15 alloy is a good candidate for magnetic refrigeration near room temperature.
A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni 50 ... more A detailed investigation of structure, critical behaviour and magnetocaloric properties of Ni 50 Mn 30 Sn 20 (Sn20) and Ni 50 Mn 30 In 20 (In20) alloys has been investigated by means of X-ray diffraction and magnetic measurements. Ni 50 Mn 30 Sn 20 alloy shows a cubic austenite L2 1 structure and undergoes a second order magnetic transition at a Curie temperature of T A c;1 Sn20 ð Þ¼333 K. However, the Ni 50 Mn 30 In 20 alloy exhibits a mixture of cubic L2 1 and B2 austenite structures having Curie temperatures of T A c;2 In20 ð Þ¼ 285 K and T * c In20 ð Þ¼ 330 K, respectively. The modified Arrott plots, Kouvel-Fisher curves and critical isotherm analysis have been used to estimate the critical exponents (β, γ and δ) around the Curie temperature. For Sn 20 alloy, the reliable exponents are consistent with the mean field model, revealing long-range ferromagnetic interactions. Nevertheless, the critical exponents of In 20 alloy around 330 K cannot be arranged into any of the universality classes of well-known classical standard models. The maximum entropy change under 5 T of Sn20 (ΔS max M ¼ 2:43 J kg :K) is slightly higher than that of In20 (ΔS max M ¼ 2:05 J kg :K). The experimental results of entropy changes are in good agreement with those calculated using Landau theory.
Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribb... more Microstructure, structural and magnetic phase transitions of the melt spun Ni 50 Mn 35 Sn 15 ribbons have been examined by means of scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and magnetic measurements. The melt spun ribbons exhibit a single phase cubic L2 1 austenite structure at room temperature with a space group FmÀ3m, and lattice parameter a ¼ 5.956 Å. The DSC results reveal the first order reverse and forward martensitic transition (M s ¼ 147.4 K, M f ¼ 133.7 K, A s ¼ 155 K and A f ¼ 171 K) with a thermal hysteresis of about 21.3 K around the martensitic transition between heating and cooling. The thermomagnetic measurements show that the melt spun ribbons undergo a second order magnetic transition at a Curie temperature T C ¼ 310 K and a first order martensitic transition at T M ¼ 160 K. The critical behavior associated with the magnetic phase transition has been investigated through the isothermal magnetization measurements around T C. The critical exponents have been estimated by several methods such as the modified Arrott plots, Kouvel-Fisher method and critical isothermal analysis. The critical exponents values b ¼ 0:456, g ¼ 0:88 and d ¼ 2:929 are close to those predicted from the mean field model revealing a dominated long-range order of magnetic interactions. For an applied magnetic field of 5 T, the maximum magnetic entropy change ðDS Mmax Þ and the relative cooling power (RCP) values around T C are of about 2.105 J/kg.K and 132.5 J/kg, respectively. The melt-spun Ni 50 Mn 35 Sn 15 alloy is a good candidate for magnetic refrigeration near room temperature.
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